machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment. I read every comment and respond to most. n.b. There is a list of my first 800 posts in my post of 17 June 2021, titled "800 Posts"
Stuart T has made a new valve chest gasket for the Fowler R3 traction engine. I will see him in a couple of days to pick it up. Meanwhile, a few days free, so I have started another home renovation project.
I installed this bath in our house about 45 years ago. A neighbour was renovating his bathroom and knowing of our fondness for antiques, he asked if we would like his old bath. Otherwise it was headed for the rubbish tip. It was cast iron, on lions paw feet. The taps were very large, and truly superb. They were mounted on a porcelain or ceramic shelf, which had the logo “Fin du Siecle” (“End of the century”) so it was probably manufactured in the 1890’s which was the period of my neighbour’s house. Unfortunately the surface of the ceramic shelf was badly crazed. The bath had many coats of paint. But it was huge, had an elegant shape, and we loved it.
My wife, SWMBO, spent many hours stripping off the many coats of paint, and sanding the surface smooth. I had the cast iron feet brass plated, we coated the brass surface with a lacquer to prevent tarnishing. I made new gaskets for the taps, and cut new washers from leather. The washers were also huge. The ceramic shelf was professionally sprayed with a bath resurfacing paint, and the “Fin du Siecle” logo was sadly covered (after photographs were taken).
It was so big that it would not fit through the bathroom doorway. But our bathroom renovation involved replastering a wall, so the very heavy bath was carried in through the opened wall by a much younger me, and a group of my then much younger friends. SWMBO says that our daughters learned to swim in that bath, it was so big.
The interior surface of the bath was professionally sprayed with a bath surface renewal paint, and that surface lasted about 15-20 years. Then it started to fail around the plug hole, with rust appearing, and gradually spreading. Then maybe a decade later the taps stopped functioning. I disassembled them, but they did not appear to be repairable with my skills at that time (pre metalworking). So I bypassed the antique taps and installed valves further back in the line.
We stopped using that bath, except for washing the dogs, which accelerated the surface deterioration. It really started to look disgusting, and earlier this year we made the decision to “fix up” the bathroom. That involved buying a new bath, repairing marble tiles, rebuilding the shower recess, replacing the shower screen, and getting the floor heating fixed.
But the first task was to remove the old bath.
Remembering how heavy it was, I was in no hurry to start the job. But a few days go we were visited by my son in law, who is Samoan, and incredibly fit. He is built like a rugby player. He noticed the large box containing the new bath, and offered to help remove the old one. So we did. I was not expecting to do this job just then, but the offer was too good to refuse, so we did.
Regrettably, it was impossible to remove the old bath intact, unless a large hole was made in a wall. So, I used a 9″ angle grinder to cut it into 3 pieces. The cast iron was about 8-10mm thick. A very dirty job. We wore safety glasses, ear muffs, and face masks. Even so it was a VERY dirty job. I had previously disconnected the taps and drain, removed the tap handles, drain, ceramic shelf, large lead drain plug, and lions feet.
The ceramic shelf, with logo and artwork painted over. Separate taps and outlet, and soap holders. Would have been the height of fashion in 1890’s.The 120+ year old bath looks sad without its tap handles, water spout and ceramic shelf, and getting cut up.
The two of us carried out the 3 pieces, and with some effort, lifted them onto the Landcruiser tray. My eldest daughter wanted the old bath for her garden, but now that it is in pieces has decided to take only the lions feet and the round end of the bath. I will store the other cast iron pieces in case I want to use the metal for a model.
2 pieces removed, one to go. The marble surfaces were protected with wooden boards and rubber mats. Some marble wall tiles had become loose, so were removed pending reattachment.I expect that this end of the bath will become a planter box for my daughter’s garden.
The cast iron dust is incredibly dirty, pervasive, and spread into nearby rooms.
I am happy that this difficult, dirty, heavy job is done.
But, I am sad that the grand, old, antique bath had to be destroyed to be removed. I feel like a Vandal.
Installed the rotation preventer yesterday. It stops rotation movements when the mill-drill worktable is raised and lowered.
The brackets and linear stage rails were bolted together after positioning the brackets on parallels on a machined surface table (from the now closed Ford factory).Then attached the assembly to the column by bolting together the halves of the brackets. A bit of adjusting of tensions to get the slide working smoothly on the rods, then bolted the linear stage to the gear enclosure with 2 more cap screws. The Metabo drill provides plenty of power through the worm and gear to raise and lower the heavy worktable, and electronic speed control provides excellent control.
When everything was tightened, No worktable rotation movement at all was detectable, even when pushing on it, but the raising and lowering movements were unaffected. It is a rigid setup.
So, how accurately is the position maintained during raising and lowering?
A laser pointer was set on a millimeter scale. Not super accurate, I agree, but should give some indication. The laser is only 40-50mm from the scale.
Then lowered the worktable about 300mm.
The laser dot is bigger at this distance but it is still centered on the same point.
This setup feels really rigid, and I feel pretty sure that it will work well.
Discounting the cost of the incorrect specifications of the first laser cut parts, the overall cost was about $AUD400.
The traction engine crankshaft is installed, and just needs valve timing for the job to be completed. But I am taking a break from that project to get back to the mill drill attachment to prevent work table position changes when adjusting the table height.
I had bought a used linear stage mechanism…..about the same cost as 2 pieces of ground 30mm shaft, but it included the precision bearings in the stage table.
… and had some 20mm mild steel plate laser cut to attach the linear stage rods and table to the mill drill….
…… but unfortunately got one of the dimensions wrong and had to scrap the laser cut cut brackets, remeasure them, redraw them, and order more laser cut parts. An expensive mistake.
Anyway, the new parts were collected yesterday, and today I started to machine them.
I used the opportunity to redesign the brackets to reduce their weight, as well fixing the mistake. The crucial dimensions are the diameters of the 3 circular holes, and the distance between the large hole (for the column) and the two small ones (for the linear stage rods). I specified the diameters to be 1 mm smaller than final dimensions to allow for final machining, to adjust for laser draught and laser cutting marks.
I was pleasantly surprised by the quality and accuracy of the laser cutting. There was no visible variation from 90 degrees cutting angle, and the dimensions were probably accurate enough to use with just a minimum of cleaning up. But I had to remove the 1mm machining allowance from the 3 holes.
The setup on my 28 year old CNC mill. Note the spray coolant. 7mm depth of cut, 0.5mm side cut. All straight forward.
Then I milled some deep pockets for the cap screw heads, and drilled some 5mm very deep holes ready for cutting the screw threads for the 6mm cap screws.
Then disaster! Just finishing drilling the final 90mm deep hole, and the drill bit broke. With no part of the drill protruding. I had used coolant, and frequent withdrawals to clear swarf, but it was a long series drill bit, and I must have pushed it just a bit too hard. I could see the broken end of the bit about 20mm down the blind hole. No hope of getting it out that way…. too deep to weld and I do not have access to an EDM machine.
The big hole was to be cut into halves, then bolted together around the mill drill column.
Hmm, I wondered if I could bandsaw almost to the embedded high speed steel drill bit from 4 directions, without actually cutting into it then snap the steel halves apart, and maybe grab a protruding part of the drill bit? Worth a try? (If that did not work I might be able to break up the drill bit with an old carbide milling cutter. That has worked for me previously.)
Nothing to lose, and I could think of no other solutions, so that is what I did. Here I am cutting the part where the broken drill bit is in the lower part of the workpiece. I cut almost to the drill bit from 4 directions. I could have used an ultra thin cutting disk in an angle grinder, but decided to start with the bandsaw. Didn’t end up using an angle grinder.
Then held the piece in a strong vice, and ever so gently bent the pieces back and forth until I felt them snap apart.
Inspected the drill bit ends. The end in the through hole just fell out. In the blind hole there was a protrusion about 3 or 4mm long which I was able to grab with pliers. And glory be, I felt it move, and gently pulled and rotated and it came out! Lucky!
Then tested the parts on the mill drill column….
PERFECT FIT! Both halves clicked into position. (second half not shown in this photo). The rectangular cutout fits over the table elevating rack.
Then spent some time tapping the holes for the M6 cap screws. All good.
I need to drill, counterbore and tap holes in a similar fashion for the 30mm rods, but they should be much less deep (only 50mm). Then to repeat the entire exercise for the other bracket. Next workshop session. Then to set up the apparatus and measure how effective it is. It had better work. Next installment in a few days time.
Yes. As usual, this project has taken at least twice as long as I had planned.
But, the making of the crankshaft has finished, and I have started to install it in the traction engine.
I installed the valve eccentrics, approximately in their correct positions. I had marked the eccentrics according to their position on the old crankshaft. The exact timing positions will be determined when everything is installed.
The crankshaft was placed in the main bearings. I had made the crankshaft with the bearing spacings according to the original plans. Then realized that the original maker had varied some of the dimensions, including the distance between main bearings. So I needed to gain approx 2mm between the main bearings. I achieved that by taking some width off one of the gears on the lathe.
Today, I started to fit the big end bearings. I had deliberately made the big end journals 0.1-0.2mm bigger than the old ones, knowing that I would have to increase the diameter of the big end bearings.
The 3 jaw chuck is holding a smaller independent 4 jaw (because I did not have a suitable backing plate for the small 4 jaw. And I needed a small 4 jaw so the bearing halves would seat on it.). The big end bearing is held in its engine housing, and the original bearing hole was clocked in the 4 jaw as accurately as possible, after tapping it against the jaws with a light hammer. Then the bearing was turned to the slightly larger diameter.
The crankshaft with the main bearings and big end bearings tightened. The eccentric rods are held out of the way with aluminium wire. The shaft turns but it is very tight, and will need further freeing. I have used some “Gumption” but it needs a bit more. Maybe running the engine on compressed air will free it up.
A quick test with the flywheel in position looked promising in terms of run out.
When turning the big end journals the supporting block for each crank had to be heated to release the Loctite and remove the block, then re-glued in place after the journal was finished.
Then the mainshaft itself was turned.
But first the centres for the big ends were cut off, after making sure that the journals were totally finished!
In this instance I used the horizontal drop bandsaw, because I have not yet replaced the damaged blade on the vertical bandsaw. There is a piece of steel clamped in the vice, and the weight of the workpiece is sufficient to keep it in place during the sawing.
As you can see I used a flood coolant-lubricant. Here getting the dimensions close to final using a tungsten insert tool, at 235 RPM. At that speed balance weights were not required. Depth of cut was 0.5mm, and frequent stops for measurements, so it was a time consuming process. And to disassemble and clean the cross slide DRO glass scale. I reversed the workpiece where required to cut towards the headstock. I still do not know exactly what the steel grade is, but whatever, I had several changes of inserts as they lost their edge.
The final machining step (I hope), was to mill the keyway grooves. That took another 6 hours.
The CNC rotary table was very useful for setting the angles, and locking the shaft in position, on the mill. Two 6mm carbide endmills were required to cut the 10 keyways. Here I used a spray coolant, powered with compressed air. A little less messy than the flood coolant.
The crankshaft is almost ready to be installed in the traction engine. The support blocks to be removed finally. The shaft ends to be chamfered. And the crank weights to be drilled, tapped and bolted in place.
I had marked the eccentrics positions before the original disassembly, and here I have installed them approximately in the same positions on the new crankshaft. Of course they will require small adjustments later. The gears slide smoothly on their splines.
Doubtless there will be installation issues. The old crankshaft deviated from the plans in quite a few respects, and sometimes I was unsure whether to copy the old crankshaft, or to follow the plans. “Copy the old crankshaft” was the general advice, but there were some obvious discrepancies which had to be addressed. I can only hope that I have made correct decisions.
During the turning of the big end journals yesterday, the digital display on the lathe stopped showing the cross slide position. So I completed the task relying on micrometer measurements. A more traditional method, but not totally in my comfort zone, being more used to the digital readout method.
Today I investigated to cause of the failure. First I switched the cross slide and longitudinal feed cables on the display unit to see whether the fault was in the sensor component/cable or the display itself. The fault was clearly in the sensor component/cable. These do fail occasionally, and are not horrendously expensive to replace, but waiting for a replacement was going to be annoying since I am in the middle of a very interesting job (making a crankshaft).
Hmm. I wonder if it is a fault which I can fix? I have never taken one of the units apart previously. And it is probably full of springs and bearings as well as a fragile graduated glass slide. But, nothing to lose. So here goes nothing…
Unbolting the scale from the lathe was straightforward, since I had originally installed it. But it was quite a few years ago.
Moved the sensor manually with it switched on. Still no movement on the display.
So I disassembled it.
Unscrewed the end block, and gingerly separated it from the aluminium case.
Then pulled out the rubber seals (the blue strips in the following photo).
The glass slide components, after wiping clean.
Then pulled out the unit with the electronics and the sensor. This was where I was expecting small bits to spring out and go flying across the workshop, lost forever. But no. It came out as a unit.
The board, glass scale, bearings etc were all covered with coolant and tiny chips!
How to clean them? I used compressed air.
Then wiped the glass graduated scale and protective blue seals with a clean microfibre cloth.
Reassembled the unit. Not difficult.
Switched it on.
Hallelujah! It worked!
Note to self. The sensor unit needs to be made coolant proof.
Finish turned the big end journals today. I decided to make them slightly bigger than the original shaft, because there was a measured deficiency of approximately 0.1mm – 0.15mm (? wear, ? manufacturing error) between the original shaft and the original split bearings.
I had rough milled one of the big end journals a couple of days ago, and Loctited a block into the crank slot of the other big end. I decided to finish turn that journal first, then to remove the loctited block and glue it into the finished crank slot, before rough milling then finish turning the second big end journal. If you follow me.
That all took another half day. And, I experienced my first significant (but not fatal) stuff up in the job.
Copious coolant, 135rpm. Of course the workpiece is centered on the big end journal. Here the tool is approaching the journal to be machined. The packing piece is glued into the other crank slot, and will remain there until the journal being machined is totally finished.
After finishing the first journal and changing the location of the packing piece the second journal was roughed out on the mill. I was much more confident about this method by now, and was more aggressive with the cuts. Used coolant throughout, and the cutter was in good shape at the end. I roughed the diameter to within 1 mm of the final dimension to reduce the time for finish turning. Note the use of my shop made clamp to reduce backlash and vibration. That worked much better than the previous soft wire method.
When I was happy that the journals were finished, I glued in a second packing block, centered the shaft, and turned the curved outside shape on the crank flanges.
As you can see, there is a lot more swarf to be made yet.
Oh yes. The stuffup. After one side of the first journal was turned the insert was blunted, so I rotated the insert. But unfortunately dropped it and chipped it, so it was replaced with a new one. My error was that I did not notice that the tip radius of the new insert was different… 0.8mm radius rather than the original which was larger and made a nice fillet at the join (see above photo). The new insert made a much sharper join, still with a radius, but much sharper. Not fatal, but not ideal.
In the next session I will recheck all of the big end journal measurements. If all are good I will cut off the side flanges at the ends of the shaft, removing those centers for ever.
I will see if my fixed lathe steady will fit into the middle gap between the cranks. If it fits, I will take a smooth light lathe cut of that section and install the steady. Then finish turn both outside sections of the mainshaft. Then move the fixed lathe steady to one of those outside ends, and finish turn the central section. The central section is where the eccentrics are located.
If the fixed steady does not fit in the middle section I will finish turn that section first, after installing the fixed steady on the longest outside section of the mainshaft.
Those possibilities are to keep the mainshaft as rigid as possible during all of those turning steps. (that list is more for my benefit than yours, dear reader).
p.s. So far, there has been no discernable distortion of the workpiece despite removal of over 20kg of swarf. That has been assessed on a granite surface plate, after filing all of the machined edges of all metal tags and lips.
Not finished yet, but the end is in sight. Maybe 2 or 3 more workshop sessions.
Today I roughed out one of the crank journals. I had hoped to do both of them, but had some problems to solve.
Normally big end journals are turned on the lathe. With this crankshaft, the lathe tool “stickout” is over 40mm. And the section is initially square, so the turning would be VERY interrupted. So I decided to try a new method (for me), of converting the square section steel to round section on the MILL. This is the setup…
On the left is a rotary table, powered by a stepper motor. On the right is the tailstock. The heights were adjusted using a height gauge. The Y position was determined with a clock gauge. The vertical mill has a 12mm carbide end mill running at 2000prm. Depth of cut initially 0.5mm. Rotary table is set to run for one complete turn. The stickout of the endmill is about 45mm, to just clear the flanges… the weakest link. I broke another endmill, so reduced the rotation speed, and added spray lubricant. Even so, it was not a secure setup. It improved after I replaced the ziptie with soft wire.
The end result, a “roughing in”, was not too bad. Since the end mill was centered over the journal, then moved to the lateral extents. each cut bulges slightly in the middle. In retrospect I could have flattened the cylinder by creating a final spiral. But since it will all be finished with a lathe cutter, that is irrelevant.
Note the Loctited spacer in the other crank space. I started the same process on that big end journal, spotted the difference, and aborted the process just in time.(!).
So I transferred the crankshaft to the lathe…. and discovered that the toolpost was too wide to permit turning due to collision with the shaft end block.
Here is the turning setup. If the toolpost looks a bit odd, I have removed about 10mm from the near side, to allow clearance. This was a damaged toolpost, so I had no hesitation in modifying it. Note the extreme tool stickout. That is why I wanted to NOT have interrupted turning. So I have not yet tried the setup, but I think that it will work. The journal is currently about 38mm diameter. It needs to be reduced to approx 26mm. Stuart Tankard made this tool, and its left hand companion. Thanks for the loan Stuart! I will proceed gently. And use flood coolant-lubricant.
So, again, not much to show for 5 hours in the workshop! But progress is happening. And this is a fascinating job!
Incidentally, the rotary table stepper motor became too hot to touch during the milling. But it did not falter. Very impressed. I think that it would be possible to do the entire journal shaping on the mill. Maybe next time.
Another workshop session. About 5 hours today. That is about my limit before I need to put my feet up.
Today I hacked into the solid heavy strong shaft, to form the crank web slots.
This is the setup. The workpiece was held in the mill vice. The end pieces were levelled using a height gauge, and supported with adjustable screw jacks.
The carbide cutter was 12.7mm diameter, and flood coolant was used. Each cut was 2.5mm deep.
The 2.5mm deep cuts were extended to 38.1mm. Then the slot was widened to 19.05mm using the same cutter, but taking 19mm depth per pass, and 1mm side cut per pass. The right hand slot is finished, and I used an old broken 3/4″ cutter shank to gauge the width. How did I break a 3/4″ solid tungsten cutter? I don’t remember and don’t intend to.Old and new line up pretty well. Actually mine are more accurate, according to the plans.Those deep slots will need to be packed when the big end journals are turned, and also when the mainshaft is finish turned. Otherwise tailstock pressure could distort the crankshaft.
So parted off x2 19mm buttons from some 36mm shaft. They slide into the gaps, and will be loctited in place when necessary.
Finally for today I measured the big end bearings, main bearings, eccentric holes, and mechanical water pump eccentric hole. The bearing holes were all approximately 0.2mm larger than the old shaft size, probably due to wear. They are all close to round, rather than oval. So Intend to machine the new shaft to match the largest diameter of the bearings. If necessary I will ream the old bearings to match the new shaft with a circular shape.
I am a bit apprehensive about turning the big end journals because the work piece will be severely unbalanced. Obviously I will install some balancing weights on the lathe face plate, but then there is the situation of the long stick out length of the turning tool, about 40mm. I am pondering the possibility of using the motorised CNC rotary table to very slowly rotate the workpiece, while converting the square sections to cylinders on the vertical mill. Then finishing the journals on the lathe. Hmm. Might just work.
This is the moment when I allow myself to envy the owners of 5 axis CNC mills, in which a crankshaft is made in the duration of a YouTube video, with perfect results, no mess, just a bit of expert CNC programming. But then… if it was that easy, everyone would be doing it.
You might be wondering why I am posting these updates after each workshop session. Partly it is so the day’s activities are recorded while still fresh in my mind. But it is also my method of keeping a diary, for possible future reference, in case I ever have to make another crankshaft (like for another triple expansion steam engine?).
I decided, after advice from several readers, to rough turn the mainshaft.
But first, just in case you were wondering, the kitchen entry stairs are finished, except for a bit of painting.
But just in case kitchen stairs are not your thing, back to the Fowler R3 traction engine crankshaft ….
Today I rough turned the mainshaft.
First I tested and adjusted the tailstock offset.
My method of adjusting tailstock set over is to turn disks at the ends of a 300mm bar between centers, with a very sharp tool, taking fine cuts, and measuring the diameters. Then adjusting the set over and taking further cuts until both diameters are equal.
Then mounted the crankshaft blank between pre-drilled centres…
And turning towards the headstock. This was interrupted turning +++. I took 1mm off the diameter, then as I became adjusted to the machine gun rat-a – tat-tat, gradually increased the depth of cut to 1mm, with a spindle RPM of 175/min. Later I added coolant. Note, I used a ball bearing tailstock centre for the rough turning. I will use a solid centre for the finish diameters.
Then turned the workpiece around and using the same DRO settings, did the other ends towards the headstock. Including the faces of the cranks.
I was not too fussed about actual dimensions. They were roughing cuts, and at 38mm diameter there is plenty of extra material. It should be much smoother machining to reduce the diameters of the cylinders, compared to rounding the square sections.
After getting quite a few opinions about stress relieving the workpiece, after all of this machining, I have decided to take the workpiece up to 600deg c, for 1.5 hours, then slowly cool. Probably unnecessary, since it is black steel, but it can’t hurt. Then I will do the final dimension turning.
p.s. about a week later. No detectable movement despite a lot more material removed. And some further expert advice that heat treatment might actually cause problems. So, given the controversy I have decided to do nothing. ie. No heat treatment.
Not a lot more to show after today’s 5 hour workshop session, but the debulking with the bandsaw and mill is complete. The 26.5kg bar now weighs just over 7kg.
I started to bandsaw the remaining 2 blocks, and was just finishing a long cut when the sawing sound abruptly changed and the cutting stopped. WTF? Examination showed that the blade teeth were still sharp, but the teeth set on one side was gone. I think that there must have been a hard inclusion in the steel which stripped the side set. Whatever, that blade is stuffed. To make matters worse, I did not have a replacement on hand.
So, I had to revert to milling to remove the waste blocks. Just to reiterate, the blocks are 38.1mm x 38.1mm x 180mm so it was a lot of swarf again. But I am now using flood coolant, so the swarf was not red hot, and the 12.7mm carbide cutter survived intact. I was reminded why I normally avoid coolant however. It is VERY messy.
And it took a couple of hours so I reckon that I earned this one.
The remainder of the session was occupied by measuring and marking for the crank cut-outs.
Almost every surface of that solid bar will disappear when the turning in the lathe is done. The only surfaces which remain will be the bar ends, and the square surfaces where the counterweights will be attached, and they will not be visible.
The next step.
Do I cut out the crank slots, or do I rough turn the mainshaft? If I cut out the crank slots then I would install some packing blocks, then turn the mainshaft. I cannot see a significant advantage in either next step. Any thoughts?
Yesterday I showed my model engineering group GSMEE, the bare old crankshaft, and the milled and marked lump of steel from which I am gradually removing all steel which is not crankshaft, and turning it into hot, sharp tiger snake repellant, I mean swarf.
“why don’t you just fix the old one?” (I tried. Unsuccessfully)
“why don’t you TIG weld the joins in the old one?” (possible, but Nah! It would distort, and would require finish turning, and I would probably be unable to use the existing gears, eccentrics, and big ends).
“You are going to get a lot more swarf”. (Yep!)
“What are the crosses for?” (So I know which bits to remove)
And some helpful suggestions….
“Cramp the steel vertically on the CNC mill, and drill the centers using CNC movements” (yep!)
“Machine the journals a bit oversize, and re-machine the bronze bearings because they will be worn, and a bit oval” (yep!)
“Turn between centres. Use a solid tailstock centre, not a bearing type” (Yep!)
“Turn the journals toward the headstock, and reverse the workpiece to complete the other side” (yep!)
And, considerable skepticism that the job would be completed successfully. (Understandable. It IS a challenge. But so far so good).
Today another half day workshop session. About 5 hours.
First task was to center drill the turning centers for the mainshaft and the big end journals. I marked the positions on a surface plate, using a height gauge, but the actual drilling using a center drill bit was determined by cramping the workpiece to a large angle plate, establishing a master face, and using CNC to locate the drilling positions. I was pleased to note that the CNC positions lined up pretty precisely with my measured positions. Then turned over the workpiece, cramping the same face to the angle plate, re-established zero X and Y positions , and drilled the other end. Those center drilled holes will determine the axes for the mainshaft and big ends, which are the essential reference points.Deeply drilled holes for some heavy, interrupted turning sessions.
But before the turning there is a substantial amount of steel to be removed by other means.
“Other means”.
First I tried milling, using sharp carbide end mills 12mm diameter. After I had broken 2 newish end mills, I thought about other means.
First, I used a bandsaw to make deep cuts. That steel is 38.1mm thick, and the cut is 38mm long. That is the thickest steel that I have ever cut with a bandsaw. I was REALLY surprised how quickly the cuts were made. Each one took 70-90 seconds.
Then I thought about using the bandsaw to make the long cuts, up to 200mm long, through 38.1mm steel. But the bandsaw blade was 25.4mm wide, so I chose to make a milling slot 25.4mm wide to allow access of the bandsaw blade. In the process I broke a HSS then a solid carbide 12.7mm cutter. Expensive.
A bandsaw cut 200mm long, in 38.1mm thick steel. It took 7.5 minutes. Surprisingly quick and effective! But cutting the slot was problematic… broke two cutters.So, for next one, I just used the bandsaw, making two angled cuts to remove 90% of the waste, then milling the hump out. That was easy. And quick! Way to go!.After the tidy up milling. That is half of the debulking process. Another half to be done tomorrow. Already the lump of steel is a lot lighter. Currently 10.5kg. The old crankshaft weighs 3.3kg, so still a lot of material to be removed. Just a reminder that the original weight was 26.5kg!
SO. I have formed an opinion about removing waste metal. BANDSAWING BEATS MILLING, HANDS DOWN! (but for finishing, milling wins.)
Well, actually it was a re-certification, for 3 boilers. The 1:4 traction engine has a 7″ diameter boiler, with a maximum pressure of 100 psi. and is coal-wood fired. The vertical test boiler is 6″ diameter, rated to 100 psi, and is gas fired. And the Trevithick dredger engine at 1:8 scale, is rated to 40 psi. Although it was designed to be fired with coal or wood, it is also gas fired. Mostly at exhibitions it uses steam produced by an external boiler, but the boiler in the model engine acts as a receiver for the external steam, so it also has to be certified to be run in public.
During the years of the Covid lockdowns none of these boilers were used much, and they were all out of certification. So with life returning slowly to normal, and exhibitions planned for 2023, I contacted our club’s boiler inspector, and arrangements were made. Since there were 3 boilers involved, and 2 other members of our club wished to speak to the inspector about their current builds, he offered to come to Geelong, which was incredibly helpful.
As preparation for the inspection I ran each boiler to make sure that all was in order.
I have previously described the problems found with the traction engine. Various water and steam leaks were fixed, and the crankshaft repaired, although a more permanent crankshaft replacement is underway. The boiler inspector was really only concerned with the boiler itself, the water pumps, the sight gauge, and the safety valves. Two actual tests were performed. The boiler was filled with water, then the hand pump was used to hold the pressure at 20% above working pressure i.e. approx 125 psi. The boiler was checked for leaks and distortions. Not surprisingly none were found. Then the water level was drained to normal, the fire was lit, and steam pressure increased to 100 psi. The fire was encouraged to burn as fiercely as possible, using the funnel blower, and later the steam blower. That was to make sure that the safety valves were functioning adequately, and at the correct pressure.
Then the vertical test boiler underwent the same procedures, but with a gas burner.
And the same for the Trevithick dredger engine, also with a gas burner.
All of the boilers passed the tests, and certificates were issued, for 4 years. Phew!
However, the big issue, the Elephant In The Room, is that the rules for small steam powered engines, trains, traction engines, which are fueled by gas have changed. In future all gas fittings have to be installed by licensed gas fitters. All gas fittings have to be purchased, approved and stamped, not made by the model maker. And currently, NO gas fitters in Victoria, and possibly any other Australian state, have been willing to be involved with engines, trains etc. which have been made by model engineers. Even installing gas burners which are sold for barbeques, camp stoves etc will not be permitted to be used in public exhibitions of steam engines, locomotives etc.
Which means that no gas fired model steam engines will be able to be run in public. It remains to be determined what the situation will be with gas fired internal combustion engines.
It should be stated that the new rules are under intense scrutiny and discussion. There is some hope that common sense and sanity will be applied. Or the current nanny state, Occupational Health and Safety nonsense will be applied to its fullest extent of stupidity. We can only hope that this will not be the end of a fascinating, stimulating, entertaining, and educational hobby.
Boys of various ages having fun on the R3 Fowler 1:4 traction engine. White shirt unwise when driving a steam engine. Photo taken 2019.6″ vertical test boiler with Southworth pump, is sometimes used to power the triple expansion model steam engine.
And the 1:8 scale model Trevithick dredger engine. The cylinder is inside the boiler!
P.S. In case you were wondering, the round column mill modification is still underway. Currently waiting for the column brackets to be cut by the laser cutter.
The first step was deciding which grade of steel to use, and the size and section of steel.
I have made several crankshafts, but only one was from solid steel. The others were all from pieces which were joined with pins and Loctite. And all of them were substantially smaller than the traction engine crankshaft. The solid steel crankshaft was for the model triple expansion steam engine. It had 3 cranks, so was a balanced design. I turned it from stainless steel.
The traction engine crankshaft has 2 cranks, at 90 degrees, so is not a balanced design. It turns relatively slowly, and the balance is provided somewhat by balance weights which are attached later.
I was advised to not use bright steel because of a tendency to change shape when machined, due to relieving internal stresses as material is removed. So I contacted several steel local suppliers about purchasing some black steel solid rod or square section.
The three small circles and black rounded rectangles are an end view of the crankshaft
The red circle with a diameter of 114.3mm is the minimum size of round bar stock if the crankshaft was turned with the mainshaft centralised.
The red circle with a diameter of 107.8mm is the minimum size of round bar stock if all 3 centres just fit within the bar.
If square section stock is used the minimum size is 76.2mm x 76.2mm.
In all cases the length of stock is 416mm.
Since steel bar is sold mainly by weight and grade, I looked for a supplier of square section black bar.
But square section black bar has radiused corners, as in the shape on the left. So, to end up with 76.2 x 76.2mm square section I needed to use 90x90mm with the radiused corners. Long story shortened (mercifully, if you are reading this), I found an engineering works locally who was prepared to cut off a 420mm length, shown in a photo in the previous post. It is heavy!
Next steps will be to mill the ends to 416mm, and 2 long faces to a sharp corner. Then to mark and centre drill the centres for the mainshaft and the big ends (the three small black circles in the diagram above). That will be today’s task.
Later that day…..
Squaring the ends of the 90x90mm lump of steel. Hmmm.. those radiused edges could be an issue…Taking off 1mm per pass with a tungsten tipped milling cutter.When the corners were squared, my 90x90mm bar just ended up 76.2 x 76.2mm. I always mark the waste with a cross. Don’t ask me why.The end result of an afternoon’s machining. That bar is too hot to handle. I will measure it accurately tomorrow.Oh. And a bucket of swarf after a quick clean up. A lot more to come.
In a previous post I explained how I replaced a broken roll pin in a fabricated traction engine crankshaft. The repaired crankshaft worked well enough for the renewal of the boiler certification, but I suspect that one of more of the other roll pins is also damaged.
But!….
… there is still a flywheel wobble of about 1mm at the rim. 1mm does not sound much, but it looks horrible. So I have decided to make a new crankshaft. Using a single piece of steel.
The crank-shaft is at the right of the photo, beneath the big ends, eccentrics and main bearings.
For the third time in a couple of weeks I removed the crankshaft from the engine. The first time took me more than 4 hours. Second time was quicker. Today it took me only 93 minutes, including the time wasted looking for small open enders.
And meanwhile I bought a chunk of steel big enough to carve into a replacement crankshaft….
That lump of black steel is 90 x 90 x 420mm. It weighs 26kg! The faulty crankshaft to be replaced in front. The gear and the eccentrics will be removed in the next workshop session. And the original plans of the crankshaft at rear.
The crank-shaft has two cranks, at 90 degrees from each other. The shaft itself is about 26mm diameter.
My plan is to use the milling machine to remove most of the waste, then to finish the accurate diameters on the lathe, turning between eccentric centres.
It is apparent, looking at the size of the bar, that most of it will end up as swarf. Oh well. On the floor it will keep the tigers out of the workshop.
I purchased this mill-drill quite a few years ago, and generally it has performed well. 6 spindle speeds, morse 4 taper, 3 auto feed speeds. I installed an X-Y table, a 6″ Vertex vice and the digital quill movement scale. All good.
But, the crank handle height adjustment for the head, and the table were both very heavy to use. And they are getting heavier as they get older.
As you can see, I tidied up the area especially for the photo.
So I installed a motorised raise and lowering mechanism for the work table. That was detailed in the post “Motorising a Mill Drill Table” Feb 2021. For a variable speed, reversing motor, I used an old Metabo drill, which has heaps of power for the job. I removed the crank handle, and installed a worm and gear in a 100x100x150mm box. It has worked very well, although I probably geared down too much, because even with the drill at full speed, it is slowish to raise and lower the heavy table.
BUT. The round column is very frustrating. When changing the height of the work table the XY position is not maintained, and that is a real pain when doing multiple tasks in a fixed XY position.
I tried attaching a laser light projected onto a vertical line on a nearby wall, and that worked in a fashion, but not reliably.
Then I used the gear rack to keep the table in a fixed vertical position, but that was also unsatisfactory, because the rack would flex and the position was not accurate enough.
So, I should have NOT purchased a round column mill drill to start with. And I would NEVER do so again. But I have put up with the limitation and have continued to think about possible fixes.
Then I saw this on Ebay. And thought. “I have a use for this!”
It is a linear stage. The 30mm polished steel rods are 800mm long, and the threaded block runs on precisely machined bushes, presumably bronze. The winding handle, 16mm x 2mm threaded rod, and revolution counter are of excellent quality, but will not be used. The item appears to have had little use. There were some extra bits attached which I will not use.
And here it is cramped into the position where it will be used…..
The Metabo drill is removeable, but basically lives in that position. The worm is visible in the photo. Normally the worm and gear casing has a metal cover.
I will make brackets to attach the bars to the round column in this position. I decided to attach the round bars rather than the end blocks to the brackets. The central block will be bolted to the worm and gear housing. I am confident that this setup will stop the work table from changing XY position when the height position is changed. It should not get in the way of drilling operations.
Drawing of the brackets. I intend to make them from some 20mm thick mild steel which I found in my workshop. I was hoping to get the brackets laser cut from aluminium, but was informed that there is a limit of 10mm with that metal. They could cut 20mm of steel, but I would need to add a machining and perpendicularity allowance of say 1mm. Still thinking about that possibility. Might be simpler to just mill the brackets myself. It is 352mm X 177mm X 20mm.
I will post some photos when it is finished. And some measurements of the rigidity of the setup.
The lovely 1:4 scale Fowler traction engine which I bought in 2017 has had little use in the past 3 years, so I have decided to sell it. The lack of use was mainly due to Covid shut down of steam meets and exhibitions. While Covid restrictions have ceased, my interests have changed, and I now prefer to concentrate on smaller, stationary steam engines.
But first I needed to renew the boiler certification. The boiler is constructed from 4mm thick copper, silver soldered, and was made by an experienced engineer, so I do not expect any significant problems with the re-certification. Just to be sure, I ran the engine on compressed air. Immediately I noticed that the flywheel was rotating more slowly than the crankshaft. The cause was a sheared pin which joins two segments of the crankshaft.
The flywheel has always had a slight wobble, but now it was more pronounced. Obviously the crankshaft needed to be repaired or replaced. Initially I hoped that all that would be required was a new pin. It was a 1/8″ roll pin, and I hoped that I could tap it out and simply replace it.
I have the original construction plans for the engine, and those plans recommend a solid crankshaft in the interests of longevity. However, the original maker had chosen to make a built up crankshaft, securing the 8 joins with roll pins, and probably Loctite.
I contacted the original maker of the engine, an elderly gentleman living interstate, and we had a long and pleasant conversation. He was surprised that the crankshaft had failed, but did not recall the details of the construction. He strongly recommended removing the crankshaft from the engine and working on it in the workshop, a decision which I had already made.
Long story shortened. It took me 4 hours to remove the crankshaft, and on the workbench about 10 minutes to punch out the broken pin, and separate the crankshaft parts.
Crankshaft, big ends, eccentric rods, main bearings and flywheel removed.The crankshaft with undisturbed eccentrics, set up on 2 V blocks on a granite surface plate. With the 2 parts pushed together. But something was wrong. With the broken end clamped in the V block, the other end was held about a millimeter above the V block. WTF!
By this time the join had been cleaned with acetone, primed with Loctite 7471, and glued with Loctite Wicking 290. And reamed the hole to accept a number 1 taper pin.
So I checked the diameters of the mainshaft at both ends. 23.47mm at the broken end. 22.86 at the high end!!! Bugger. I should have checked before gluing. But why would the mainshaft have different end diameters???
Oh well! I decided, foolishly with hindsight, to reassemble the whole engine and see if the discrepancy was noticeable.
Next day, another 4 hours, and the reassembly was complete.
Rotated the flywheel. And it was horrible!! The flywheel runout was not “noticeable”. It was horrible!!
It had to be redone. Or do I just bite the bullet and make a new crankshaft?
I decided to redo the repair job, lining up the parts in the lathe.
Long story short again… teardown was much quicker this time. Experience counts.
This time I took a very light skim off the shaft and face using a very sharp cutter, to ensure that the ends and roughness were removed. Then held the broken shaft in a collet chuck which I know is very accurate. But found another problem. The shaft at the other end of the crankshaft had not only a smaller diameter, but was also at a slight angle axially, so I could not use the machined centre in the end of the shaft. So I set up the fixed lathe steady pictured, mounting it at the main bearing location. Trouble was that I had no accurate method of centering the steady. I described this setup to my engineering group, and was informed that I should have used a set up rod machined to the diameter of the end of the crankshaft, to set the position of the steady. Makes sense. My bad.
Oh well. I will reassemble the engine again. If it is again horrible, I will either do the whole job again, properly this time, OR MAKE A NEW CRANKSHAFT.
I have a feeling that I will be making a new crankshaft.
p.s. I allowed a day for the Loctite to cure, then deeply reamed the existing hole, and reinserted the taper pin in the enlarged tapered hole. This time the head was buried, but there should be enough purchase to remain intact.
Reassembled the engine, and turned it over to check the flywheel wobble.
I will not claim that it is perfect, but it is very close. I will not start making a new crankshaft just yet, but that is the next step if this repair is eventually unsatisfactory.
I decided to purchase a new lathe chuck, a 6 jaw, 160mm diameter, Chinese “Sanou”. I had watched Stefan Gotteswinter’s review of these, and based on his expert assessment, made an Ebay purchase. I found 2 Australian suppliers, and chose the cheapest one. All straight forward so far. Money paid using Paypal. A few days later, a call from the vendor, “very sorry, no stock remaining”. “But you have stock listed on your site”. “Very sorry, all gone, do you want me to order more from China.” Oh well. No real rush. “OK, yes I will wait”. But then the first hint that maybe all was not as it appeared…. “Ignore the tracking number. I will contact you when it has arrived”. Hmm. That is strange. But I waited. And waited. Eventually, 6 weeks after the initial order, I requested a refund.
I had another call from the vendor. “Very sorry, there was a problem with the Chinese supplier. The prices of shipping have increased, and the Chinese supplier used the container space for another customer who had paid the higher cost, so your chuck in my shipment was not sent”. “And the cost of the chucks is higher”. Yes, we know that prices of everything are rising. But why did it require my request for a refund to elicit this rather convoluted and slightly unbelievable explanation. And why was I originally requested to not check the tracking number? And why did it take 6 weeks to be notified of all of this?
Anyway, I did receive my refund. But what if I had not followed up on the non delivery?
Case 2.
Another Ebay purchase. This time for a battery powered screw gun for sheet plaster, because SWMBO has asked me to hang the plaster in one of her project house renovations “and will save a lot of money if we do it ourselves.” Now, hanging plaster is not a favourite activity of mine. In fact it is on my list of activities for which I would always employ a tradesman. But “happy wife = happy life”. So I agreed, but used the occasion to purchase another tool. Yes, I do have a disease.
So, another Ebay purchase, Australian supplier of a good German brand which I always use for battery tools. Not cheap, but reliable, and my one and only complaint to the manufacturer (Metabo), many years ago, resulted in immediate and generous restitution. Order placed, Paypal payment. Within a few hours I received a receipt, and a tracking number for postage from interstate. Now that was quick postage! Very impressed. Or was that too quick?
3 weeks later, it still had not arrived. Postage services in Australia have been very variable lately. Sometimes items arrive in a day or two. Some turn up months later. Some never turn up. I checked the tracking number, and it appeared that the package had been received at the interstate postal depot. But no record since then.
So I contacted the vendor. Return message. “it appears that your package has gone missing.” “very sorry etc etc.” Immediate refund. So immediate, that I had to wonder. I was expecting the vendor to ask me to wait patiently a bit longer, to which request I would have agreed. Why the immediate refund?
Meanwhile I have gone cold on the idea of hanging plaster. I have not told SWMBO of this change of heart, and she does not read these posts. Or does she? I will get an answer to that question very soon I suspect.
There are so many scams about these days. Like most people, I seem to get at least one scam email per day, which I just delete immediately. I NEVER click on email attachments, unless I am certain of the sender’s identity and purpose, but even then I check first. And I NEVER buy anything advertised on Facebook, having been scammed twice there, with NO COMPENSATION from Facebook for running fake advertisements.
Both of the above cases happened in the past month. Case 1, where there was a tracking number supplied, but obviously no article actually posted, has made me very suspicious about tracking numbers providing proof of postage. Case 2 could be a genuine postage loss, but if my suspicion about tracking numbers is correct, then maybe it was a scam too.
Julius deWaal has drawn and published plans for model engines, most recently the Bolton/Bertinat plans for the triple expansion marine steam engine. The triple plans are available to download free of charge at ….https://modelengineeringwebsite.com/Bolton_Bertinat_1.html
I made a model triple using the Bolton plans and castings, several years ago.
Here is a recent photo of my model triple expansion engine operating on steam at the Royal Geelong Show. In the background is a full size version, which is a permanent, operating, attraction at the show. My model is 250mm long, 250mm high, and weighs about 10kg. It has a Stephenson reversing mechanism, and an exhaust steam condenser, both of which work.
It was a difficult build, taking me about 3 years, with a couple of sanity restoring long breaks during which I built other models. The build was detailed on this blog. To check the progress photos and descriptions do a search on “triple”.
I was very happy to finish the build, and ecstatic to see it working on compressed air, and then steam. When exhibited it always attracts a lot of attention, with its myriad of small moving components.
But, I was a bit unhappy, because it does include some errors. These were partly due to the suboptimal plans, and more so to my inexperience. The errors are not apparent to a casual observer, but I know that they are there. They do not interfere with the operation on steam. I had considered making another, bigger, triple, but always backed away, due to the time, complexity, and cost.
But a friend recently sent me a link to the new deWaal plans. The link is below the first picture, above. The new plans are metric, very detailed, and TWICE the size of the originals…. i.e. a model built to the deWaal specs would be 500mm long, 500mm high, and probably weigh around 40kg!
I must be a glutton for punishment, or a bit nuts, because I am seriously considering making another triple, using the deWaal plans and not buying castings but using bar stock. And maybe using some home made castings.
Click on the picture to see a short video of the Fowler R3 steaming away.
Dear Reader, if you follow my posts you will know that I had stopped posting on WordPress because I had exceeded the 13gB memory limit.
I have been copying old posts to medium.com, and posting new ones there. Today I was copying some more, and I happened to notice that my wordpress memory limit had increased. There had been no notification of an increase. Maybe it was a mistake. So I posted the above video as a test, and to my surprise it was accepted. So I contacted support to see if there had been a change of policy. No, no policy change. Apparently it was a bug. Could it have been someone being kind? I asked. Possibly, was the reply. Do you want it changed back? NO!! I screamed.
So I have a 10gB reprieve. Enough for several years at my rate of usage. May be temporary. Time will tell. Meanwhile I will recommence posting here on WordPress, as well as medium.com/@johnsmachines
Very few of my johnsmachines.wordpress readers have switched to medium.com, so I was seriously considering pulling the plug on all future posting. So this is a reprieve. You will have the choice of seeing my posts here on WordPress, or at Medium.
P.S. The traction engine, tender, kids cart, custom fitted trailer with winch, and ~200kg of steaming coal is for sale. Located near Geelong, Victoria, Australia. Best offer over $AUD20k. Certification will be renewed prior to sale. Kids not included.
If you are a regular reader of my posts, you should know that nothing new has appeared on this site for months, or will appear on this site. in the future. No more storage space and wordpress is not interested.
Too few of my readers have so far moved to the new site.
The posts on this site are being progressively moved to the new site, but this site will CLOSE TOTALLY in a month or two.
SO, if you have any interest in my future posts you should check out the new site. Otherwise, I will take the hint, and disappear without ceremony, altogether.
Note, Reading posts is free, but to leave comments/feedback, you need to register with medium.com. Registration is free. Do try the “listen” option. It is remarkably good! The only drawback to “listen” is that photograph captions are not read aloud.
At the next level, for $US50 per year you have unlimited access to the millions of posts on the site. I am exploring some of these.
It is not a particularly interesting post, but if the new provider is OK, that is where future posts will appear.
And… the result of an experiment which was successful.
Today was very warm in southern Australia, but I successfully made a brass part for a friend. It took a couple of hours to design, and then about 3-4 hours of machining to make. See later photo. It is a bracket to hold a water gauge on a full size boiler.
I came home, cooked dinner for my wife and myself. And we agreed that it was delicious.
The evening was still very warm, and very still. Stars just appearing.
I had some xmas present cigars, and I decided to light one up, outside on our verandah. It was the first one for 3 weeks.
Bliss.
So still, that the smoke rings travelled for 2-3 meters before dissolving.
What could be better? Ah… some Laphroaig single malt. Lovely peaty flavour.
And yes it was a magnificent duo.
And then I had a brainwave. Something I have never tried before.
I dipped the mouth end of the cigar into the Laphroaig for a a moment or two. It wet the end but just enough to transfer some flavour. And continued to draw.
Bloody superb!
The cigar lasted about 50 minutes. I continued the dipping every 10 minutes or so. What a discovery!
Probably reinvented the wheel, again, but I record the blissful result in case it is original.
If you like cigars, and whisky, try it. Otherwise, stay healthy and avoid both.
I will remove the wrappers tomorrow, and finish the butt in my Meerschaum pipe. Life is good.
8 years, ~900 posts. 13gB storage full. WordPress offers the solutions of buying a business package at 3 times the price, or deleting old posts to free up some space. I have removed almost all of my videos, with considerable reluctance, to make space to finish the posts about the Armstrong 110pr model cannon construction. However I still get comments from posts posted when I was a newbie, so I am not prepared to delete any more of them.
Just a thankyou to you, my reader. Questions, comments and communications from you are the grist for the mill of blog posters, and I am no exception. I have really enjoyed the journey. Feeling a bit sad, but I will resume my private diary entries, instead of venting my thoughts on johnsmachines.com
I had said that I would move johnsmachines.com to another platform, but now I am not so sure. Some repairs to my house are my next priority, and that will be too boring to blog. At this time I am not moved to start another model, but down the track, who knows?
I had saved the last little bit of storage space for the final photos of the Armstrong 110pr model cannon. Photos of the finished model follow.
The wooden carriage and traversing platform were stained with Japan black, then several coats of spray lacquer. It will be rubbed with steel wool and wood oil to give it a silky smooth finish.Focussing on the rear tangent sights. I might add some locking screws to the sight posts later, but then again, I might not.About 10º of elevation, provided by removing the quoin, and resting the barrel on the Smith’s elevating screw via the bed. Note the iron binders on the ends of the wooden slides.Top view. Queen Victoria’s cypher, the barrel weight (just over 4 tons), and the proving arrow. No touch hole on the model. This view also shows the asymmetric position of the sights, caused by canting the rear sights ~2º, and moving them 2mm to the left so they are equidistant from the bore at the nearest point.Almost horizontal with the Smith’s screw and quoin elevating the barrel. I will add some ropes and pulleys later. The right gunners’ platform needs to be pushed down a bit to sit in its correct position.From the front. The wheels only contact the slides when the rear is slightly levered up, to encourage moving the carriage from the recoil position back to the firing position. (not that this model can be fired. It has no touch hole). Also note the absence of trunnion caps, which was common in garrison guns.The model foresights were deliberately blunted to avoid observer injury; and left trunnion markings. EOC for Elswick Ordnance Company, barrel number 212, and 1862 the year the barrel was manufactured. Copied from an original Armstrong 110pr.
And that, dear reader, is that. Goodbye, best wishes, and thank you.
The 1861 Armstrong rifled breech loader cannon had foresights on the trunnion ring, and rear sights on the breech. The foresights had fixed lengths. The rear sights were adjustable and graduated for range. The foresights were vertical. The rear sights were canted at a 2º16″ angle to compensate for slight lateral deflection of the projectile caused by the rifling. The rear sights also had a lateral adjustment screw to compensate for movement of the target.
At 1:10 scale, the components of the sights were tiny, and I decided to not make the lateral compensating adjuster. But I did decide to incorporate the 2º angulation. That required the left and right rear sights to NOT be equidistant from the centre line of the barrel. The drilling of the barrel holes for the sight holders was consequently not straightforward, and I spent a couple of hours on the CAD drawing to work out the drilling positions, depths, angles etc. And then considerable time was spent setting up the barrel in the milling machine vise, so that the bore was horizontal, parallel with the mill table, and level when the foresights were drilled, and tilted 2º when the rear sights were drilled.
That took two full machining sessions over two days. I was not looking forward to it, knowing that a broken drill or other mishap would be catastrophic. In the event, it all worked out OK. Some pics…
1. The 2º canting of the rear sights was established with 8mm and 10mm thick parallels sitting on 1-2-3 blocks under the trunnions. There is an 18mm rod in the bore, sitting on the jack to hold the barrel horizontal. A 4mm end mill is creating a flat surface from which to start the drilling.
2. That is a 2mm drill bit, silver soldered to some pipe to give it some extra length. “Tension drilling” again.
3. Checking the lengths of the foresights.
4. The almost finished sights. Left rear holder needs to be shortened. And yes, the magnified photo does reveal a previously undetected superficial crack in the left weighted arm. Luckily I have a spare part if it breaks. I must have used too much force when I pressed in the driving pins.
This series of posts is almost complete. Making the 1:10 scale model Armstrong Breech Loading, Rifled cannon, 110pr* took almost a year, and these posts were originally published by johnsmachines.com in wordpress.com. Since I am intending to cancel my subscription to WordPress I have decided to transfer some of the 900 posts to this new, for me, site.
Further old posts will gradually be transferred. And some new ones will be appearing.
This is the lathe which was used to turn the 18.1″ guns of the IJN Yamato. (keep reading. Bismark comes later). The Yamato lathe was purchased by Japan in 1937 from Germany. Japan did not have the capability to make such a huge lathe. The only countries which did have that capability were Britain, USA, and Germany, and Japan did not want the British or Americans to know how big a battleship was being built. The weight of the Yamato (>70,000 tons) was not known to the allies until after WW2! It was the heaviest battleship ever constructed, and carried the biggest guns ever installed on a battleship.
1. Wagner lathe used to manufacture the Yamato and Musashi guns.
I assembled a plastic model of the Yamato earlier this year.
2. 1:350 scale Tamiya model.
….and showed my model engineering club.
Somehow the conversation involved the guns, the Yamato Museum, and the huge lathe which is being moved from its original factory, where it was in use until very recently, to the Yamato Museum.
A senior member of our group, who lives near Yallourn, Victoria, stated that the lathe which made the guns for the Bismarck was currently located in Yallourn, Victoria, Australia!!!
There was a collective dropping of members jaws. WHAT???? HOW??? It cannot be true!!
To cut the story short, further investigation by the member, confirmed that a very large Wagner lathe had been shipped to Australia, as a reparation after WW2. The lathe had been installed in the State Electricity Commission workshop to turn large generating armatures. The SEC workshop was now a private manufacturing factory, and the lathe was still there!!!
The managing director of the company was contacted, and a few weeks later 24 of our club members visited the factory with the tour being conducted by the owner-manager. The factory was fascinating, and the tour lasted over 2 hours, but I shall concentrate on the lathe.
3. This is our group, in front of the headstock, clearly displaying the Wagner Dortmund name plate. I am in there. The machines to the right are applying tungsten to the large roller seen, using a robotic arm and laser welding machine. The lady in the orange jacket is the member who told us about the lathe’s presence. 4. The 4 jaw chuck is 8’4″ diameter.
5. The lathe has 2 carriages. The toolpost is over 6′ high. The beds are covered while the tungsten coating is being applied.
6. The tailstock end of the bed, with 6 steadies. Unfortunately I could not find a serial number, but it was probably hidden behind other equipment.
The distance between centres for the lathe is 70’/20m, certainly big enough to have turned the Bismarck guns. The lathe OAL is 90′. The original tailstock and a section of bed was lost at sea in a storm during transportation to Oz. Replacements were found and installed.
Currently the lathe has a 50hp electric motor. It turns between 1 and 20rpm.
7. The factory covers 20,000m3. I could not get a decent camera view of the whole lathe. The headstock is to the left of this shot. This view is one end of one of the six factory bays.
So. That was a great day.
The factory owner manager is searching for documentation about the lathe, which is essential if the Bismarck association (and Tirpitz, and more than a few shore defense guns around France, Denmark, Norway) provenance is to be firmly established. The locals certainly believe that it IS the lathe which made the Bismarck guns. It is possibly true. The Yallourn lathe looks very similar to the Yamato lathe.
8. Bismarck
9. Tirpitz was the sister ship of Bismarck. Showing a ~18m long 15″ barrel without the breech.
Just one photo. me and my model triple expansion steam engine, running on steam, and the Armstrong 80 pr Muzzle loader, both entries eliciting a lot of spectator interest.
Maybe one more….
This is my model triple expansion steam engine, running on steam, against a background of a full size marine triple expansion engine, also running on steam! Cool eh?!
In the above photograph, taken I think of a 110pr Armstrong breech loader in Canada, of a Garrison mounted gun, there are several very interesting features. The Smith’s elevating screw for instance, and the remnants of the left hand breech tangent sight. But I am particularly looking at the flat surfaced item which is attached to the top of the breech. It took me some time to work out the function of the rather complex shaped item.
The breech block, which weighed 130lbs, had to be lifted out of the breech by two strong gunners to permit swabbing of the bore from the breech aperture (also visible in the photo), then loading of the next projectile and gunpowder bag, after which the breech block was lifted back into position and screwed tightly closed prior to the next firing.
Ah….. the flat topped attachment is where the breech block was placed while the swabbing and loading took place!
So I set about making the breech block rest (as I called it) for my model.
The rest looked complex and difficult to model. The inner surface had to fit the external surface of the breech, including two convex fillets. The external surface has to fit the breech block, without denting or otherwise damaging it despite its considerable weight and frequent manhandling. And there are holes for 6 attaching screws.
First I turned a disk in LG2 bronze. The interior surface fitted closely over the breech, including the convex fillets. I used a bullnose milling cutter to turn the fillets. Then the top surface using the scarey shell cutter. I handle this cutter with great care because it is razor sharp.Then CNC milled the shapes which hold the breech block securely…And finally drilled the screw holes and parted the fitting from the bronze disk. The under side.and the top side.Here the breech block rest is Loctited in position, ready for the screw holes to be drilled into the breech and the screws fitted.The breech block resting in place, ready for reloading.
Now, dear readers, I must inform you that I have only enough WordPress memory for another one or two posts and a few photographs.
The Armstrong 110pr breech loader cannon model project is almost finished.
The remaining parts, including the Smith’s elevating screw, carriage wheels, rope eye bolts and capstain were all described in the build of the Armstrong 80pr rifled muzzle loading model cannon, so I will not repeat those details for the 110 pr.
I will leave the remaining small memory for the assembled model of the 110 breech loader, in a few weeks time.
And since I will not delete any more old posts, that will be my final post. (unless WordPress changes their policy of not increasing memory limits. And I do not expect that to happen.)
In the final post I will notify you, my readers, of the site where I will post photos of future projects. Not quite yet decided, but it will NOT be WordPress.
My workshop uses a 6kw Phase Changer machine to convert the 2 phase supply to 3 phases, which is required by my CNC mill, DRO mill and big lathe.
When I turned it on 2 days ago, I was startled by a very loud “bang” and a puff of black smoke from the phase changer. And no power output, unsurprisingly. On opening up the machine I was pleased to note that the (very expensive) transformer looked intact. But one of the large capacitors looked a bit ragged.
1. I restarted the unit with my iPhone recording so I could show the manufacturer. The culprit is the second capacitor from the top. The replacement capacitor came yesterday.
So I have been limited to single phase equipment for the past 2 days. It did force me to finish some outstanding tasks….
2. ….Like making the traversing platform axle washers…
3. ….and making the tow bar….and finish installing the wheels.
and yesterday my colleague and friend Stuart T used his 30w fibre laser to engrave the manufacturer name, number, barrel weight, date, and Queen Victoria’s cypher.
4. Stuart and his laser. He reckons that it has been used more for my model cannons than his own work! The orange machine is a tiny CNC mill which Stuart made a few years ago.
5. The laser in action
6. The engraving as it first appears. Some polishing is required to remove the rectangle around the cypher and to sharpen the image outlines. The trunnion ring is still waiting for a cleanup after being heat shrink fitted.
30mm diameter, 11mm thick, a rail groove on the edge, circular divots on the faces. Simple!
But…
I decided to make them from stainless steel. And tonight I have multiple small cuts on my fingers to prove it.
Stainless steel is a bugger to machine. It requires slow feeds, deepish cuts, COOLANT, and sharp tools. Carbide is OK for roughing, but for accurate final surfaces, sharp high speed steel is required. And it produces razor wire. Copious amounts of it.
1. End result. Not perfect, but as good as I can manage. It took me 2 days to make 8 of these wheels. More work is required on the axles.
First I machined some 40mm stainless rod down to 31mm. Too late I realised that was too big.
Then I used a HSS form tool bit to cut the edge groove. But got too much chatter. So spent some time getting the coolant pump and nozzle working. Some improvement, but still some chatter. So I switched to a HSS parting tool 3mm wide, and that seemed to work well. The DRO was handy to achieve the final groove depth of 2.5mm, and 6mm wide. And then to take 0.5mm off each face to produce a boss 12.7mm wide and 0.5mm deep.
Then completed the parting off. Oh. Forgot to mention the 5mm shaft hole which was drilled.
But when I tried to install the wheels in the wheel brackets I realised that I need to remove about 0.1mm from each boss. This is the setup which I used.
2. A diamond cup wheel in the chuck, and the wheel wheel siting on parallels and held in the drill press vice. This worked pretty well, except that the quill adjustments on the drill press were a bit coarse. It would have been better in the mill with a DRO.
3. Oh. And I forgot. I used a HSS ball nose milling bit in the CNC mill, with a spray lubricant coolant, to make the face grooves. By this stage I was absolutely convinced of the need for the lubricant coolant. It made a huge difference to the surface finish. The vice did leave little dents in the surfaces of the wheels, but I had left a final machining allowance of 0.5mm to be tidied up in the lathe.
So, the first pic is the current situation, . Next steps are to make the washers for the axles, trim the axles to length, and drill/install retaining pins. These steps always seem to require at least double the predicted workshop time.
….The problem was that the 4 wheel brackets needed the wheel recess deepened by 2.5mm, and the brass shape had few clampable surfaces.
So, I tried option 1.
I machined a wooden jig to hold the bracket in the milling machine vice. The wood is Australian desert ironwood, which is unbelievably hard, but would not mark the brass. The pocket was machined to the diameter of the circular base of the bracket, and then sawn in half.
2. The bracket was clamped in the jig and squeezed tightly in the vice. Then machined with the slot cutter, the required 2.5mm deeper. The workpiece showed NO tendency to move.
1. Original brackets on the Elsternwick 80pr Armstrong RML’s. They appear to be castings.
2. Another wheel bracket style. This one on the Armstrong 80pr at Port Fairy. Cast from a different mold.
Previously I have made model wheel brackets using 2 different methods…. 1. casting 2.turning/milling
3. This bracket was cast from aluminium. It looks different from the Elsternwick example above, but is close to the original Port Fairy original.
4. This one was turned from brass, and was installed on the model copied from the Elsternwick originals. Not too dissimilar from the original, but still not quite right.
So, these are the wheel brackets which I have made for the current model Armstrong 110pr…
5. These are hot off the milling machine, and not yet finished. Those sharp edges will all be rounded and milling marks polished out.
I think that when these are finished they will look closer to the original than either of the previous examples, and they certainly look more robust and fit for purpose IMO. So, what do you think?
The above wheel brackets were milled from 38mm brass rod….
7. The slot was cut with a 5mm width slotter. 3 passes to get 11mm width. First pass shown here.
8. 75mm diameter, 5mm thick slotter. Shop made spindle fits into ER40 chuck. First ever use of this slotter which I bought years ago.
On reviewing this post I noticed that the slot for the wheel looked a bit shallow, and when I measured it I found that it is 2.5mm too shallow. A simple mistake, but must be fixed.
The problem is how to hold the workpiece while cutting the slot the extra 2.5mm deeper.
Possibilities. 1. make a circular jig to clamp the bracket in the milling vice. 2. just hold the bracket in the milling vice and hope for the best. 3.solder a 38mm cylinder to the top of the bracket, and hold the extension in the vice. 4. make new brackets.
At this moment I am thinking that I will try 1. and if unsuccessful move to 4.
The Armstrong 110pr model cannon trunnions sit in semicircular cutouts in the carriage cheeks. In the model the cutouts are 20mm diameter, and they are slightly deeper than semicircular. Making the “slightly bigger than semicircular” cutouts is complicated by the fact that the cheeks toe in towards the front, by 2.65º.
When I originally cut out the cheeks I made the cutouts 18mm diameter, allowing 2mm to be removed at the assembly time, and to then remove some extra material to cope with the toe-in angle. I did not know in advance how that would be done, but I figured that I would use a drill or reamer at the correct angle to remove the extra material.
Today was the day.
But when I was actually confronted with the task, I realised how difficult the job was actually going to be. I also realised that a drill or reamer was NOT going to do the job accurately or neatly enough.
1. These are the assembled carriages with the undersize trunnion cutouts, which do not take into account the toe-in angles. ( Since this photo was taken, the bolts have all been finished to length. See later photo.)
Then I had a brainwave. And I am really proud of this one. I made a round file, exactly 20mm diameter, and long enough do file the cut-outs together, exactly in line.
How to make a file?
And how to make the teeth small enough so they leave a smooth finish with no edge tear-outs?
2. A 20mm diameter piece of silver steel, long enough to allow filing movements plus handles. Here I am applying a fine knurl with the shop made tool which I made a decade or more ago. It is a clamp type, and can apply a lot of pressure. Run at 200rpm, well oiled.
3. I chose the finest pattern knurling wheels.
Ah! But I forgot something. When I measured the diameter of the “file” the 20mm shaft now measured 20.25mm. I had forgotten that knurling INCREASES the effective diameter. So I turned off the knurls and machined the shaft down to 19.75mm, and repeated the knurling. The diameter was now 20.05mm which I considered acceptable.
Since I was only intending to file wood, I did not bother hardening the silver steel.
4. The “file” after a few minutes enlarging the cut-outs.
5. After one minute of gently rotating the file, I could see that it was working!
6. One finished – in 3 minutes, and one to go (the top one)
7. And the trunnions fit the cut-outs perfectly!
Garrison based cannons did not use trunnion caps, unlike the naval versions, relying on the weight of the barrel to keep it in place. The centre of the trunnion is just below the top surface of the carriage cheek.
The file worked well in hardwood. I would have hardened the steel if it was to be used on brass or other metal.
The carriage cheeks for the Armstrong 110pr cannon have 10 roughly vertical bolts which attach the wooden slides, and also bolt together the thick planks which make up the cheeks.
1. Some woodworking on the vertical mill, using a very sharp and scarey shell cutter. I used to do a lot of woodworking, but these days I use the metalworking tools at their highest speeds to do accurate cuts in wooden parts. Here milling the rebates which fit the carriage into the traversing platform of the Armstrong 110pr.
The nuts for the bolts are all at the bottom end, and are buried in the slides. In previous model cannons I have milled pockets for the nuts, and tightened the nuts with a socket spanner, but I was not happy with the large diameter of the pocket which was needed to accomodate the socket spanner.
So, this time I decided to tighten the nuts using a screw driver, having cut a slot in the surface of the nuts.
2. This is an M4 nut, with a slot cut into the surface, which will be tightened with a special screwdriver. How to cut such a tiny slot? (excuse my dirty finger. This photo was taken after several hours in the workshop.)
3. The screwdriver tip which has been modified with a Dremel, to drive the slotted nuts.
4. This is the setup for cutting the slot. the nut is screwed onto some sacrificial threaded 4mm rod. The slot is cut with a thin cutting disk, 1mm thick, mounted onto a shop made mandrel which fits into an ER40 collet on the vertical mill. A bit of fiddling with the height settings, but once it was set, making the slotted nuts was very quick and easy. The slot was 2mm deep in the 4mm deep nuts. Plenty of thread remaining to tighten the nuts.
5. Slotted nuts on the right. Ordinary unslotted nuts on the left, which cannot be tightened except by making bigger holes, or slotting the nuts, which is what I did.
With the barrel almost finished (except for sights and engraving), I have returned to woodworking. The carriage was made of wood in the 1860’s.
I had previously cut out the carriage sides and the slide blocks, but now the parts need to be bolted together. Today I marked out the bolt holes, and drilled some. The holes were 4mm diameter, and up to 90mm long. Definitely “deep drilling”, despite being in wood. Due to the figuring in the wood it can sometimes be difficult to keep long series drill bits from wandering off to the sides.
1. The sides were pinned together and drilled in pairs after marking. The bolts are used to hold the slides onto the sides, and all are at different angles. Due to the tendency of the long series drill bits to wander, I started at the top where the bolts are visible, and finished at the bottom, where eventually they will not be visible.
2. The marks were lined up under a centre bit, and using a square to get the hole as true as possible.
3. 2 holes needed to have pockets cut with an end mill first. Yes, I know. Should not have used a 3 jaw drill chuck to hold the end mill, but it worked on this steeply sloped part.
4. After the drilling was finished, I could not wait to set up the barrel on the carriage to see how it would appear.
Next job is to continue the bolt holes through the slide blocks. And to make the transom. And then to enlarge the trunnion cutout to the correct size and angle.
5. The trunnion holes in the cheeks require some enlargement. The clearance of the trunnion shoulders to the carriage sides is a very neat fit. Note that handles have been made and fitted to the breech screw weights.
I am glad that I had no visitors to my workshop in the past 2 days.
The language in the workshop has been a touch foul.
Because I have been making handles for the previously made bronze breech blocks.
The handles are very small, very exacting, and difficult. In a word, I struggled.
End result photo….
1. Those little handles were used to lift out the 130lb breech block by 2 gunners. The handles swivel, and push down on the barrel, to lever the block out of the gas tight seal the block makes with the end of the bore of the barrel. As you can see from the scale of of my finger tips, they ARE very small.
I was not enthusiastic about this job. I had a feeling that it would be a bugger. And so it was.
2. First task to cut out the top of the handle bracket. Piece of cake with CNC.
3. Next, drill a hole into the bronze block and silver solder it into permanent position. Also, straightforward. The top was Loctited into position with Loctite 620, so the silver solder was not disturbed. So far so good.
4. Next job, make the actual handles. I milled a round rod with appropriately sized flats, then annealed some brass rod, and wound it around the shaped steel. Total failure. Did not take the shape accurately, and sprung outwards. So I tried it in copper. That worked better…
5. The copper wire was out of the scrap bin. 2.4mm diameter.
6. Then milled some brass rectangular section (6x4mm) and silver soldered the copper pieces to it.
7. Then cut the brass approximately to length.
8. Slit the brass to 2mm width on the mill.
9. Drilled the fastener holes and attached to the breech block with BA10 bolts and nuts.
10. And ended up with a breech block which can be levered out, and replaced into position reasonably accurately and consistently.
All straightforward.
So why all of the bad language?
Well, I needed 2 of these, so 4 handles. I made 2 spare.
I dropped one. Could not find it, despite hours of searching, including using a fibre optic 5mm diameter device to look under the milling machine and sweeping the floor. (no snakes in this cold weather. I hope). But no luck, so I made another.
Another handle jammed in the Dremel drill. I hear it hit the tin wall 7 meters away. I did look for a minute or 2, then succumbed to common sense and made another. The language really was foul.
Anyway. You have seen the final result. not too bad. Another bit of brass bling.
Yesterday I went with the children and grandchildren to the stage show musical “Cinderella”, by Rogers and Hammerstein, so I had to cut my workshop session short.
But in the few hours available I attached the weights to the weighted handle, and the lugs which contact the screw handle.
1. The weights were silver soldered to the handle, and the lugs were Loctited into position. I chose Loctite 620 rather than silver solder for the lugs, because I used different setups for the weights and lugs, and did not want to risk disrupting the silver solder from the weights joins when I attached the lugs. Some finishing required to remove the heat scale and lug protrusions. Even at model scale, the weighted handle works really well.
Oh. And by the way….Cinderella was marvellous! Enjoyed by everyone from age 6 to 72.
2. Appreciative audience after the show, exiting The Regent Theatre, Melbourne.
The billet of 1020 steel which I used to make the Armstrong 110pr breech loader cannon barrels weighed a bit over 10kg for each barrel.
1. 305mm long, 76mm diameter, 10+kg
2. 10+kg machined to 3.885kg
That leaves over 6kg of swarf for each barrel! How did I do it? I just removed all of the steel which was not cannon barrel (apologies to Michaelangelo).
The original trunnion rings of the Armstrong 110pr breech load cannons were made with a smaller internal diameter than the barrel. Then the ring was heated, installed, and it shrunk firmly into its permanent position. Heat shrinking multiple coil cylinders to build up the cannon was shown to be a very strong method, albeit expensive.
I decided to try the same method with my 1:10 model, and discussed the method at the recent GSMEE meeting. I listened carefully to the advice from members, read Machinery’s Handbook on the subject, and was ready to proceed.
The ring internal diameter was turned to 0.05-0.06 mm smaller than the diameter of the barrel where it would be positioned.
This is the pottery oven which I used to heat up the ring to 550ºc/1022ºf. All necessary tools, gloves, etc ready.
I was also told that once the ring contacts the barrel, the working time before the ring contracts is very short. So I was advised to make a jig so the ring drops exactly into the correct position. I made the jig from hardwood, and had a fire extinguisher handy.(but the extinguisher was not actually required.)CNC routing to make the jig. The trunnions fitted with 0.25mm clearance.
I let the ring soak up the heat for an hour or more.
Lifted it out with pliers, carefully lowered it down the barrel (having earlier has a couple of practice runs), and felt it slide easily into position.
Another ring followed later and it also dropped easily into position. I had to rotate it, and noted that it locked up after only 10-15 seconds, so the working time is indeed very brief!
The first ring in position. The second one was installed a few moments later, after the jig was removed. The barrel soaked up the heat, and was too hot to handle for over an hour. Note the scorch marks on the wood jig. And the line up scratches.I had mucked up the internal ring diameter of the second barrel, so used Loctite 620 after cleaning the surfaces with acetone and then the Loctite 7071 prep spray. Unexpectedly, probably because I did not use the jig with the Loctite join, I had more trouble lining up the marks with this one. I am sure that both will be strong enough for these models. After that I turned the 1º taper on the distal end of the barrels (the “chase”). The flat section is for the bracket which the breech block is placed on for loading the projectile and charge. The flat was also the reference plane for the trunnions.
I will clean up the blackened heat affected trunnion ring later. This was a very satisfying day in the workshop.
1. The centres were measured, marked and drilled. The squared end was held in a 4 jaw chuck and the end to be turned was held in the tailstock. Turned to 20mm dia with a “Diamond” tool holder and HSS 1/4″ cutter from Eccentric Engineering.
2. Then the turned end was held in an ER40 collet chuck to avoid marring the surface, and the tailstock end was turned.
3. One finished, one end to go.
4. Then I used the undersized laser cut parts to turn another “coil” (solid steel in the model, not a wound coil as in the full size cannon), also to be heat shrunk to the barrel.
Next step will be to turn the barrel diameter down to about 0.06-0.07mm bigger than the internal diameters of these parts. I will try to take some photos of the heat shrinking process for the next post.
Unfortunately the laser cut trunnion ring blanks were unusable because they were undersize. Rather than wait for another run of laser cut parts, with 3-5% increase in size to cope with the problem, I decided to mill the shapes from some old 27.5mm thick mild steel. In my last post I showed the preparation of the stock.
I made 2 of the ring blanks today. They have a 45mm hole, and to speed up the milling process I chose to use my magnet drill and a 35mm annular cutter to get the hole started…
1. It took about a minute to make a 35mm diameter hole in 27mm steel. Easy as. I had previously centre drilled the hole positions on the mill. I bought this magnet drill 18 years ago when I was building a large farm shed.
2. Before drilling the holes I had zeroed in the steel plate on the milling machine, and used the red locating device to replace the steel in the same position.
3. The left hole milled to 45mm diameter, 4mm depth per cut with a newish 8mm carbide bit. Just starting the second one. Much easier enlarging an existing hole than milling a deep slot.
4. Milling the outline, ramping down…..2500rpm, 150mm/min
5. …and I quickly added a spray-mister to provide lubrication, cooling and chip clearing from the deepening slot.
6. I did run into a problem with the tabs. I made them 1mm thick, but forgot that Vectric calculates the tab thickness from the bottom of the cut, not the bottom of the material. And the tabs broke before the milling had finished. Fortunately the workpieces survived.
7. The parts had 5mm taken off the wings which will later become the trunnions, then used a rounding over milling cutter as a form tool in the lathe to make a rounded fillet.
8. 2 of these made today. Tomorrow I will turn the trunnions from the squarish ends.
As explained in the previous post, it was crucial that the breech screw was tightened securely.
Watch the following YouTube video of a demonstration firing of a 110pr at Fort Nelson, video’d by Nick Cafferata, and used here with his permission. Note how the weighted handle was swung by 2 gunners and repeatedly knocked to ensure secure closure. Also note the volume of smoke from the firing, and this was a charge of only 2lb, compared with the 10-11 lb used in 1861.
2. The laser cut parts for the screw handle (left) were excellent. Unfortunately the blank for the trunnion ring was slightly too small so I will use another method to cut another using my CNC mill.
3. Milling the screw octagon on the breech screw. CNC rotary table. Beautifully accurate.
4. Octagonal piece heat shrunk to breech screw. I probably could have cold pressed it on, but I wanted to try heat shrinking because that method will be required later when fitting the trunnion ring. It is strongly held together, not budging when I turned the rear surface to 4mm thickness.
5. 1.6mm drill for the pins. This worked well after I loctited the handle to the screw before drilling. 25mm depth of drilling definitely qualifies as deep drilling. Then I heated the assembly to break the Loctite bond. Then turned a 1.6mm wide, 0.8mm deep groove in the shaft using the drilling marks as a positioning guide.
6. Facing the handle and screw. This was also completed before breaking the Loctite bond. Not a precision task, so quite happy to use the 3 jaw chuck, which is actually surprisingly accurate.
The central 18mm diameter shaft was also heated to break its Loctite bond and the shaft came free.
Next job is to make and attach the blocks to the handle which knock the octagon/breech screw, and the heavy weights to the ends of the handle which enhance the momentum of the action.
7. I had this piece of mild steel 28mmx168mmx600mm left over from a farm machinery job years ago (a deep ripper for a bull dozer, for preparing the ground prior to planting olive trees.)
8. It was rusted from sitting in a pile of steel for 10-15 years, so I took off 0.5mm from each face to flatten it and clean it up.
Watch this space to see it being CNC’d into a trunnion ring…….
If the screw which held the breech block in place was not tightened, when the gun was fired, explosive corrosive gases would escape backwards rather than propelling the projectile. An inefficient and destructive result.
If the screw was not not tightened at all, the breech block, which weighed 130lb, could be ejected with great force, and devastating, potentially fatal results to the gun crew.
So it was important that a gas tight seal was achieved when the block was inserted and tightened. That required a seat like a valve seat in an internal combustion engine, and a corresponding 45º angle on the breech block.
First I made the breech block. The plug was turned from LG2 bronze. This will seat against the steel barrel bore. In the original the block was made of steel or iron, and it seated against a copper insert seat. I decided that it would be too fiddly and difficult to reproduce the original steel/copper system, so I substituted the bronze block which fitted against the steel end of bore in a 45º seat.
2. cnc turning the bronze breech plug. The cylindrical section fits into the 18mm bore. A similar cylindrical section on the other end fits into the breech screw. The 45º section is seen.
3. A further final contour, then parting the plug from the bronze bar. I finished the parting by using a hacksaw.
4. The plug is 31mm diameter, 16mm thick.
I used 2 tools to make the seat. A commercial carbide seat cutter, and a shaped stone to finish.
5. The brass shaft and pilot were each 18mm diameter, and fitted neatly in the bore and breech screw.
6. The stone was given a 45º bevel using a diamond. The ways were covered and thoroughly cleaned afterwards.
The seat was cut with the carbide cutter, by hand and using cutting fluid. When it was 1-2mm wide, some chatter marks were just visible, so they were polished out using the stone, also by hand.
7. The chatter is visible, along with the chips which were produced by the carbide cutter. I don’t have a good photo of the end result, but it looked much better than this.
8. The hole underneath was to drain water after swabbing/post firing. The breech block is just visible.
And today I picked up some laser cut parts from the cutter. (JR Laser, Geelong)
9. Minimal cleanup was required on the 6 and 8mm thick parts. Some extra machining is required. But the 25mm thick part has some problems. It is a little undersize. Apparently caused by heat expansion of the steel during cutting. I have not yet decided what to do about this problem. I might have to get it re-made 2-3% bigger. Or I might remake it myself on the CNC mill.
So, the model engineering of the Armstrong 110pr breech loading cannon continues….
Still a fair bit of machining to finish the Armstrong 110pr breech loader.
And I was wondering whether I should spend my time fixing a very run down house rather than making model machines.
I know what I would prefer to spend my time on. And I do NOT like climbing up ladders any more. Age 72!
But SWMBO is not well. 25% of the way through chemotherapy. She is coping well. I am OK. Just.
And, I had decided that the Armstrong 110pr would be my last model build (well, not counting plastic models which I can assemble in front of the TV.)
….But, when I saw these drawings of an 1899 steam driven wharf crane, drawn into plans by Julius deWaal, I am sorely tempted.
A 1:12.7 model would be about a meter high. Contains a boiler (which would require certification), a twin cylinder double acting steam engine, THOUSANDS of rivets, many gears including bevel gears.
But, is it not beautiful, magnificent. And there are excellent plans (thanks again Julius deWaal!), and best of all, the original is less than an hour away from me by air, in Hobart Tasmania!
While I am waiting for some laser cut parts for the cannon, and tools from India, I MIGHT just start accumulating materials for this one.
The exterior shape of the barrel is one of the final steps. The basic cylindrical shape is retained as long as possible to facilitate work holding in the milling vice. Here the axes are marked. The rifling can be seen. The exterior final shape of the breech has been finish turned prior to milling the breech block cavity.The rectangular cavity is up to 20mm deep. 24mm x 16mm. I started by drilling corner holes, then used a new 8mm end mill taking 4mm deep cuts.After the 8mm endmill, the walls were tidied with a 6mm endmill. Have I mentioned before that I love CNC.This is the first time that I have tilted the milling head. It was easy, and quite predictable and steady. 20º.Not a perfect finish, but it will do. Maybe a bit more filing. The breech piece fits down there, and the breech screw locks the breech piece against the end of the bore.
A few photos of painting the model Yamato. I used Tamiya paints. Spray cans for the large areas- and hand brushes for the small ones.
1. The entire hull was primed, then the water line masked.
2. Masking tape to define the waterline, then a quick, careful spray with dull red. Lovely colour. Not dull at all.
Then removed the masking tape and applied some more tape over the red. Painted the top half of the hull, and the other modules, “battleship grey”. Then glued the modules together.
3. The wooden decking is laser cut and the individual planks are laser marked. Incredibly thin… not measured but maybe 0.25mm. And have a paper backing which when removed exposes the adhesive. The pieces are extremely accurate for the model, fitting into their spaces and around winches, guns etc. NO trimming was required. My only issue was that some areas required extra adhesive. I used Tamiya Ultra Thin Glue, and it worked well. Great care was required in positioning the sheets.
4. And some hand painting of small details. The superstructure tower, funnel, 5″ guns, anti-aircraft cannons, and main aerial. The wooden decking was then applied. See how accurately it fitted around all of the deck machinery and guns…
5. A close up of the wooden decking detail. Very impressive! And not expensive. Cost about $AUD20 including postage.
6. The fore and aft flag posts are very fine, and inclined to catch in clothing and break. After repairing them at least 10 times, I reinforced them. Can you see the dressmaking pin? The cavity to the left of my finger is the lifting well for the aircraft, leading to the hangar.
The end result….
7. Superb shape! And this photo reveals that at least 95% of the ship volume is within the hull.
8. 9 18″ guns in 3 barbettes. The wings on the barbettes are range finders. The decks around the guns were kept as clear as possible because the blast from the 18″ guns was huge. 20kg/cm^2
9. Yamato could carry up to 8 spotter planes. Launched by catapult, and picked up by the crane at the stern.
The model is complete, except for the flags and aerial cables. Took me a week to make and paint. I really enjoyed the build. And I really like the model. It was not an easy build, but the real credit goes to the people who designed and made the kit. It is truly impressive how well everything fitted together.
Now. Where to put it? And how to keep it dust free?
The 1:350 Yamato model is made of plastic. Mostly Polystyrene, but also a small amount of ABS. Different glues required for each type of plastic. Both types will hold the parts in a minute or so, but several hours are required for rigid holding.
There are 17 different colours specified, which explains why the paints were so (unexpectedly) costly. Mostly IJN grey, and dull red, for the hull exterior, and wooden deck tan. I bought Tamiya spray cans for the dull red, IJN grey, and primer. The wooden deck tan was unavailable, so I bought some laser cut sheets of impossibly thin wood, already in the correct colour, and made for this particular model. Pictures later.
So I sprayed the primer coat.
The question was whether to make the entire model, then paint; or paint the individual parts on the sprue frames before assembly ; or something in between.
I thought that painting the entire model would be simplest, but some small parts and areas would be inaccessible, and the result would be messy.
Painting every component on the sprues would leave a bare cut area on every part which would need to be touched up later, so that did not appeal. Plus it would be very time consuming.
So I decided to make the ship in modules, and paint each module separately.
1. The painting modules….. the hull is just 2 colours, IJN grey, and dull red below the water line. Some masking will be required. The other modules will be painted individually. As seen, 99% of the gluing has been finished.
2. So today I applied the primer coat. The paint is touch dry in about 10-15″. I started with the underside of the hull, then turned it over, on the box as support, and painted the decks. The box was exactly the correct size to support the deck without damaging the tiny attachments.
3. Then the smaller modules. The alligator clip attached to a chopstick was a handy way of rotating the workpieces, and minimising painting my hand.
4. Still some small parts to be attached, but they will be different colours which is my reason for not attaching them before this. This is one of the 18″ gun barbettes.
Tomorrow I hope to start applying the final colours.
Painting is really NOT my thing. So to finish the day I spent some time restoring an old small Westcott adjusting wrench which had been given to me by a friend.
4. Still some small parts to be attached, but they will be different colours which is my reason for not attaching them before this. This is one of the 18″ gun barbettes.
5. I tried to cold bend the fixed jaw but it would not move. So I used a hand hack saw to open up the crack, then bent the jaw back towards a right angle. 3 successive cuts and bends were required to get it back to 90º.
6.Then V’d the cut, almost to the box inner section. Then arc weld filled the V. It wont be as strong as the original, but will be OK for light applications.
7. Finally some time was spent grinding and sanding the weld flat, and filing the parts make them slide easily. It was still a bit sticky, so some “Gumption” was used to smooth the action. The handle was cold bent back into a nicely curved shape. I might get around to blackening the wrench by heating it and quenching in dirty sump oil.
So far, glueing up the model has been interesting and a lot of fun. Look at the progress after 2 days….
The guns and superstructure are just sitting there. The components will be separated for painting.
The tools which I have found useful are lined up.
Alligator clip on a chop stick, rubber bands, Extra Thin Tamiya Glue for polystyrene plastic, flat non serrated small pliers, needle nose small pliers, safety razor blade, sharp side cutters which I have modified so the cutters are thin and very pointy, steel ruler used as a scraper, small fine file, fine sand paper, fine tweezers (actually from my microsurgery kit of 30-40 years ago), coarse strong tweezers, and utility knife. And of course an A2 cutting board, and Tamiya Instruction book which I have found to be accurate and very helpful.
The Extra Thin Tamiya Glue is very good. It sets in a couple of minutes so parts can be finger held in position. It is so thin that it tracks into small cracks by capillary action. And it is transparent. Time will tell how paint adheres to the glue.
The Tamiya parts are also very impressive. Beautiful smooth finish, minimal flashing which can be scraped off with a finger nail. And the parts fit together very accurately, for the most part. Rarely I had to use the razor blade to make parts fit together, and that was usually because I had missed a bit of the sprue when separating the parts from the sprue.
This was one of the first areas to be glued.Large joins, like this foredeck to hull, were glued progressively, holding each bit with a rubber band. The deck has a bend, and I could not hold it in place with only my hands, but the rubber bands worked pretty well.
It was quite exciting to see the hull coming together.
Many of the parts are extremely small, and too light to feel. The fine tweezers are very handy for these. So far I have lost only one part after dropping it.
I am close to painting the components. I will use Tamiya spray cans, brush applied paints for tiny parts and fine lines, and possibly an air brush. I have been watching YouTube videos to pick up hints on the painting process. It was surprising to me just how many YT videos exist on the subject of painting model Yamatos.
Then the major components are glued together.
Then the smaller guns and other surface equipment will be glued on to the painted surfaces.
P.S. Another 1/2 day gluing up these tiny planes. One more to go.
These really tested my eyes and hand control. Cotton bud for scale.This cheap Banggood LCD microscope was very useful. Only trouble was that it magnifies my shakes. (Mustool G1200)odel
In common with many other males, (whoops. Possibly females as well, although I know of none.), I have long had a fascination with battleships. Of all eras from the ancient Greeks and Romans, Nelson’s, dreadnoughts, WW1 and WW2. Read the novels, made models from kits and from scratch. I have quite a library of books.
Recently, I purchased this book…
It was not cheap. But absolutely worth every cent. Available from various vendors. I got mine from Amazon.
336 pages. 350 colour views, including some original photographs, and lots of details. 1020 scale drawings of excellent quality. 43 pages of history and specifications. The bulk of the book is superb quality pictures and drawings.
These battleships, at 72,000 tons, were the largest ever constructed. And they mounted the biggest guns ever used on a battleship at 18.1″. Each of the 3 gun turrets weighed as much as a heavy destroyer, 2500 tons. They were 250 meters long, and 50 meters from keel to the top of the superstructure. Their 4 turbine engines drove the ships at 30knots/50kph. Each ship had 25,000 tons of armour, up to 560mm thick!!
“Awesome”, seems insufficient.
The Imperial Japanese Navy had them built to outgun the most powerful battleships of the US Navy and western powers. However they were dinosaurs, and both were sunk by aircraft. Neither fulfilled their intended role of fighting other battleships.
The book is divided into 4 sections….
Section 1: Introduction, Superbattleships and Summary of Service. 43pp.
Section 2: Primary Views. 25pp.
I cannot overstate the quality of the drawings. Just magnificent.
Section 3: The Drawings. Subdivded into general arrangements, Hull structure, Superstructure, Rig, Armaments, Fire Control, Fittings, Aircraft, Boats, Author’s Model. 252pp
18 pages are devoted to the 18.1″ guns.
Section 4: Yamato and Musashi at sea, Remains of Yamato and Musashi 12pp. The pictures “at sea” are computer constructions, using the author’s model, and incredibly convincing. Initially I took the pictures to be of the originals.
Both ships were sunk by massive US air power, with the loss in Yamato’s case of 90% of its crew of 3,300 sailors. Almost as sad, almost all of the original construction plans and details were destroyed by the IJN after the Japanese surrender.
So, if you have any interest in battleships, massive marine engineering, WW2 naval history, or ship modelling, this book is an absolute must.
Consequences??
After reading the text, and going through the pictures multiple times, and being captivated by the wonderful lines of the ships, I decided to make a model of Yamato. Kits vary from 1:1000, to 1:100, with the larger scales being in the thousands of dollars.
I made plastic assembly models when I was a kid, and once as an adult when I was laid up for 6 weeks after an injury (see later photo). In this case I settled on this kit. Tamiya is a well respected brand. The kit is 1:350 scale. Cost about $AUD150. I hope to interest a grandson to get involved.The paints required cost almost as much as the Tamiya kit!The ABS plastic components look excellent, with hardly any flashing, detailed instruction booklet. There is provision for batteries and remote controls, but I doubt that I will go that far. The hull is big! 751.5mm long.
The following is the only surviving plastic model of mine. Another ship with wonderful lines.
Cutty Sark. Even after blowing off most of the dust, it looks more like Shackleton’s “Endurance”. And needs some TLC.
A question to my readers….. would the progress of making the model Yamato be of any interest?
For reasons which I will not detail here, I am spending more time at home, and much less in my workshop. Work on the Armstrong 110 pr breech loader is progressing, slowly. However, the rifling is complete.
I detailed the rifling setup in a previous model build, but in case you missed it……
The barrel is held in a jig which is clamped to the CNC mill quill. The mill spindle is turned off, for obvious reasons. The cutter protrudes from a 16mm shaft. The brass bush increases the diameter to 18mm to fit neatly into the bore. I should have remade the entire shaft with 18mm bright steel, but I thought that this modification would work with a lot less trouble. It did. Sort of. The cutter was 3mm wide, and I ground the actual tip to 0.9mm width.The cutter is mounted to the CNC rotary table with an ER40 collet. The depth of cut is determined by the screw at right, and the maximum depth of cut set with the 2 locked nuts. The mirror is for inspecting the cuts which finished underneath and at rear.
The setup took several sessions to complete. I had previously drilled and D bit finished the bore, and drilled and cut a large thread to accept the breech screw. Then I turned the exterior of the barrel so it would fit the jig. It will be turned to its final shape in a future session.
I could not find actual specs for the twist, so I randomly decided on 90º. The cut started in the powder chamber and finished just beyond the muzzle. The rifling in the original started distal to the projectile chamber, but I had to ignore that due to limitations of my setup in accessing the adjusting screw. The powder chamber and projectile chamber were slightly bigger than the bore in the original, so I might be able to machine away the unwanted rifling in those areas in my model.
30 rifling grooves in the model. The original had 76. But in an 18mm bore the 30 cuts are only 0.9mm wide, and that was as fine as I was prepared to grind the cutter. The cuts are about 0.25mm deep, which is to scale. I will polish the bore later.
This is the breech piece. From a 1.25″ high tensile bolt, with an 18mm hole drilled and reamed. The thread is 8tpi. An unusual pitch for the size. 60º form. Further shaping of the ends to come, but I decided to make the female thread in the breech first.I cut the thread on the lathe manually, but the HSS cutter tip broke and I had to regrind it after the thread had already started to form. As you can see, the reset cutter position was a bit out. But I corrected the position and pressed on. How do the experts reposition a threading cutter? As per the original threads, I left flats in the female floors, and ground off the peaks of the male thread. (someone can correct my terminology here…)Anyway, the breech piece threads in snugly and nicely. Quite tight but screws in by hand.…and an 18mm silver steel rod fits well into the breech piece and into the bore of the barrel, so the threads are well aligned.
Despite the errors, this thread has worked out pretty well. I have learned a lot, and I reckon that the next one will be better.
The breech piece will next act as a tailstock centre for turning the exterior of the barrel between centres, after removal of the fixed steady.
This project is progressing slowly. Other issues are taking time at present.
There are 3 major components on these cannons…. the traversing platform, the wooden carriage, and the iron barrel. And a number of smaller components… the compressor (the recoil suppressor), the elevating mechanism (Smith’s screw), the sights, and various rope eyes.
I usually have something in mind to work on when I enter my workshop, but sometimes I just proceed where the mood steers me. I have actually been working on all 3 of the major components, with most progress on the traversing platform, which explains why the posts have been rather fragmented. Most of the work so far has been woodworking, but recently I had an urge to do some metalworking. So I made a start on the barrel.
The first step was to buy and cut to length the 1020 steel shaft. Then the piece was mounted in the 4 jaw chuck, and dialled within 0.05mm at the chuck. The tailstock end was supported in the fixed steady, and also dialled in. I was not trying for perfection because it is a case of time and diminishing returns, and straightness of the bore and concentricity between the bore and the exterior of the barrel are the main concerns.
So, the next step was to drill the bore to 16mm, using the extended drill bit which I had fabricated for the previous cannon, after centre drilling. The resulting hole was 305mm long, appeared to be straight, and just a bit rough.
Drilling the 16 x 305mm hole took 15″. I touched up the drill bit cutting edges with a diamond lap, and cleared the swarf every 10mm or so. Plenty of cutting fluid used.
I wanted a final bore of 18mm diameter. I have an 18mm reamer, but only 120 mm long, so I made an extension rod to fit the Morse 3 driving tab. But first I had to drill the bore closer to 18mm. So I made a D bit from undersize 18mm drill rod.
The silver steel / drill rod is 17.94mm diameter. The flat is milled, removing 8.94mm and leaving ~9.0mm. The cutting end was hardened by heating to cherry red , then quenching in oil. It was still able to be filed, so not hard enough, so I repeated the heat-quench cycle, using a water quench, and that worked well.Using the belt sander to give some side and rear relief. Later I added a chamfer to the cutting corner (see next photo).Cutting corner on the left.The “business end” as requested by John Marshall. This is after cutting through 305mm of 1020 steel, and it needs another touch up with the diamond lap. initially I used the D bit as shown on the belt sander above, but the cut improved after the bevel was added with relief to the cutting corner. The only purpose for the recess is to accumulate swarf during the cutting process. But the recess fills quickly and it needed cleaning out every 5-10mm of drilling depth. The D bit was held in a 40ER collet in the tailstock. Plenty of cutting fluid was used. The chips were cleared every 5mm of cut. The D bit was sharpened 3-4 times during the process using a diamond lap. Enlarging the bore to 17.95mm with the D bit took 15min.This was taken after using the D bit. The surface finish was improved further after passing the reamer. I am not concerned by the rough appearance at this end because it will be machined out to 28mm for a depth of 50mm to accomodate the breech screw and breech plug.The breech screw is shown in drawings of the era as a buttress thread, with a pitch of approximately 1.25″. I have some 1.25″ diameter threaded rod, category H2, with a pitch of 1/8″ which at scale 1:10, is very close to the original, although not buttress profile. The drawing is very close to full size for the model. I drilled, D drilled and reamed the through hole, and am considering how I will cut the thread into the breech of the barrel. Still pondering whether to try to cut a buttress thread…
And the traversing platform now has the metal surface strips screwed into position..
The 1mm thick stainless steel strips had been laser cut and 2mm holes laser drilled. I had to countersink the holes so the screw heads were at or below the surface, so provide a smooth surface for the carriage slides and trucks (wheels). The countersink tool is carbide. I wanted a smooth flat surface to work on, so used a fly cutter on the wood to produce such. The counter sink bit self centres well.The screws are 1.6mm diameter. In that size I had to settle for Phillips heads rather than simple slotted. The larger circular cutouts are for the wheel posts, yet to be made.
Having commenced building a 1:10 scale model of this gun on a wooden carriage and traversing platform, I am also finding information about its history. First the build progress….
Glueing the traversing platform pieces. And a 4mm long series drill bit.
Gluing required some planning. The brass stops rebates were tricky to make last time because the platform was already fully assembled. So this time I made the rebates and installed the stops prior to gluing up.
Then there is the matter of the long, 4mm, holes across the multiple pieces of the platform, which is up to 152mm wide. Wood is not uniform like steel or aluminium, and deep drilling wood with small diameter drill bits usually leads to wandering crooked holes. So I measured and drilled each piece separately, prior to assembly. A tricky and exacting process. All except for the outside pieces shown being clamped above. They were drilled, one side at a time, after that side was glued, using the existing holes as a drill guide. I was happy with the results of the drilling and gluing.
Cutting out the carriage cheeks with a 6mm endmill. The workpiece is screwed to the sacrificial base piece with large woodscrews (not visible), then the required holes for the model are drilled through workpiece and sacrificial base and bolts are inserted. These bolts stop the workpiece from moving in the final stages of cutting the part free. The carriage cheeks will not be parallel in the final assembly, being narrower at the rear than the front, and the holes will need to be modified at that stage, so I have drilled them undersize at this time. Same goes for the trunnion cut outs.Glued and drilled traversing platform (one of 2); laser cut 1mm stainless steel strips ready for attachment (AUD$55 including material. Probably saved me a day and more accurate than I would have managed), and CNC cut carriage cheeks, straight off the mill. Recycled Victorian Mountain Ash floor boards).
Not so much workshop time lately due to family factors, so I have been reading and searching references. And thinking about how to machine the barrel. Important to get the sequences right. And to have available the correct tools.
A is the screw which compresses the breech block E into the copper seals F and H, after the projectile and charge have been loaded through the breech. B is the weighted handle which operates the screw. C is the breech coil. D and J are further coils. K is the trunnion piece which was forged including the trunnions.
The originals were made using the Woolwich “coil” system, in which components of the barrel were made into various sized and shaped cylinders by winding white hot strips of iron or steel around a mandrel, then hammer welded into a single fused mass. The various cylinders were then accurately turned on large lathes into the final pieces which were heat shrunk together, and finally furnace welded. The Armstrong 110pr had 7 such major pieces. Only the innermost barrel cylinder was steel.
There were 2 barrel designs of the 110pr guns. The above diagram is the 72cwt version, which was 2″ shorter than the 82cwt version. The latter has more taper to the chase of the barrel, and will probably be the one which I model.
The 2 types of 110pr barrels. You can see my metric conversions of the dimensions. And a few dimensions scaled off the drawing. I think that I will make the 82cwt version.
I will not be making my model using the coil method, but I am probably going to make the trunnion ring with trunnions as a separate item, and shrink it onto the barrel, along the lines as described by jefenry.com. Still thinking about those big asymmetric double start threads on the breech screw. I have a high tensile 32mm bolt and nut which I am considering using.
The scaled bore should be 17.78mm. I will approximate that to 18mm. Will need to extend a 17.7mm drill bit, and to make an 18mm D bit from silver steel. Jefenry welded an extension to an adjustable reamer to finish his bore. I will possibly use that technique also.
So. Having made the decision to make a model rifled breech loader, Armstrong gun, on a wooden sliding carriage and wooden traversing platform, I gathered my references. A lot of these guns were made, 959 in use in 1878. Many on wooden carriages, some on iron carriages. They were used in several wars, and I will be delving into the history. Examples of the guns exist in quite a few countries including UK, USA, Canada, and Australia. There are references in Wikipedia, and several artillery books of the era (1860-1890). Various models have been made and documented, including good descriptions, particularly by jefenry.com.
I have several reasonable scale drawings, including some kindly sent by jefenry. (Thanks again Jeff!)
This is the 110pr breech loader on a sliding carriage, and standard traversing platform.
In the drawing above, the traversing platform is identical to the ones under the 80pr Armstrong RML’s which I recently modelled, so my previous experience will be useful for the current build. The carriage for the 110pr RBL is similar, but not identical. The barrel itself will be quite different, and will be the main challenge in the current build. Apart from the breech block, and breech seal, there are 76 (!) rifling grooves, compared to 3 rifling grooves in the RML. I am already thinking that I will be reducing the number of grooves, to maybe 28.
Another handy resource which I found during my Internet searches of Armstrong 110pr’s, is ETSY.com, a Canadian site, where the Armstrong 110pr has been CAD drawn in very fine detail, and available for $AUD34. The drawings are not perfect in every detail, but even so I rate them as very good. Only available as Fusion 360 files, but Fusion 360 is available free of charge for hobbyists, with some restrictions relating to file numbers and some features.
Yesterday I purchased a lump of 1020 shaft, 1270mm long. I only required 305mm, but the supplier was unable to cut it for 3 days, so I took the whole piece. A burly worker picked it up as if it was made of balsa wood, and put it in my car. I struggled to unload it at the other end. 40+kg/ 90lb.
Wanting to get started, I cut off two 306mm billets.
…and weighed the 306mm piece…
10+kg
The next step for the barrel is to rough drill the bore. I have an extended 16mm drill bit from the previous model, but will have to modify a 17.75mm bit and extend an 18mm reamer or make a long 18mm D bit, before I can proceed. So instead, today, I made a start on the traversing platform.
Actually, I have decided to make one for myself, as well as the intended gift.
Having made a few errors in the machining sequences last time, hopefully I can avoid the mistakes this time. Also, with multiples of some components, such as wheel brackets, and rope rings, I will be casting some of these in bronze, and getting laser cut parts for others such as the metal slides.
The original Armstrong barrels were constructed in multiple pieces which were shrunk together, using the “coil” method to construct the pieces. The trunnions were on a separate ring which was forged, then machined to final shape, then shrunk into position. I am considering machining the model trunnion ring separately, and shrinking it into position, but the rest of the model barrel will be turned from a solid piece of 1020 steel.
I had thought that the 1:10 scale model Armstrong 80pr rifled muzzle loader would be the last cannon which I would make. It is currently being given finishing coatings to the woodwork. Later this year it will be given as a gift to a family member.
To be honest, having made five 1:10 scale model blackpowder cannons, I am ready to move back to my first modelling passion, which is steam engines. I had no real interest in weapons or guns or artillery, except as a means of increasing my understanding of history, specifically military history. I have no interest in firing guns, although I must admit to an illicit satisfaction in watching You Tube videos from USA of cannon modellers who can actually fire their creations.
My interest in cannons started when, as a newbie in CNC machining, and looking around for a project to use my newly acquired CNC lathe in 2015, I made a model long gun.
1:10 scale models of a 1779 24 pounder long gun, and 1804 carronade of the same bore. Making them was interesting, and the associated history was totally engrossing.Then the Ottoman cannon of 1465, again 1:10 scale, over 500mm long.
The Armstrong 80pr muzzle loader, scaled from the originals at Port Fairy and Warrnambool.Another Armstrong RML 80pr. I kept this one.
And the most recent Rifled Muzzle loader, the same 80pr Armstrong Barrel, on a Dwarf carriage, and wooden traversing platform.
Almost but not quite completely finished in this photo. Since then it has been cleaned, stained, and lacquered.
I truly thought that this would be the final cannon which I would model. So I could get back to my model steam engines.
Like this one from 2-3 years ago, now gracing our kitchen, with decorations by SWMBO.
Trevithick dredger engine and boiler, of about 1805. 1:8 scale. The possum and the budgerigar are not real. Neither are the two T. Rex’s fighting on the boiler.
BUT….then my eldest daughter, who has absolutely NO interest in cannons, asked ” are you going to make a cannon for me?” I must point out that this daughter rescues injured animals and takes them to her vet, is vegan, the most pacifistic and socially conscious person that I know. I questioned why she would want a model cannon. “I just do” she replied.
Oh well. I guess that I will be making one final model cannon.
I spent a day searching my books, Google Images, Wikipedia for a cannon which would look interesting as a model, be interesting for me to make, and for which some plans or drawings are available. I offered my daughter the choice of my existing models, but no, she wanted one built just for her.
Then I thought of jefenry, my reader from the USA, who has made several model cannons, including one which intrigued me when I first saw his pictures and videos several years ago. It is a 1:9 scale Armstrong rifled breech loader, 110pr, of 1861. One of the first breech loaders of relatively modern times. (Breech loading cannons have been around since medieval times, but they were less reliable than muzzle loaders, more inclined to explode and kill their own gunners.). The Armstrong 110 pr RBL saw action in several wars, including against Japan, the NZ Maoris. It was the largest cannon on HMS Warrior, but was replaced by the more reliable muzzle loaders.
So that is what I will model for my daughter. An Armstrong 110pr, rifled breech loader, on a dwarf carriage and wooden traversing carriage. Here are some pictures.
110pr Armstrong at Fort Henry, Canada. I presume that the traversing carriage is a reconstruction.And the 1:9 model of a naval version of the gun, which was made by jefenry. Check out the making of the cannon, including rifling, at jefenry.com and watch his video of firing the cannon at https://youtu.be/m3pC0eDvs90
So, my plan is to make a 1:10 model of the barrel, on a carriage and traversing platform like the Fort Henry example above. Not sure how much of the build will be featured on this blog. I am again very close to my WordPress.com memory limit.
These daily posts might be becoming a bit tedious but you need to realise that I write them for my own diarising purposes as well as entertaining yous.
First today, I deepened the countersinks on the carriage stops which I had installed yesterday, and filed the bracket surfaces until the carriage showed no signs of catching on high spots. Then reassembled all of the bits in the vicinity.
I had machined some hardwood (Australian Mountain Ash, a close grained, hard, stable, pale hardwood) for the side steps, and today I made the brackets to support the side steps.
There are side steps on both sides. The one not visible is smaller. R1 R2 and R3 are the steel supports.
But, when I examined the steps today, I decided to remake the side steps, using the dark red hardwood Jarrah, the same as the rear platform.
The Jarrah side steps. They will age to a dark red colour, like the rear platform. The grey desk mat is A2, to give you an idea of the scale.
The steel brackets were cut from 50mmx25mmx1.5mm rectangular section tube.
Cutting the RSS.Bolted to the side steps. They look a bit rough at this magnification. The lip at the top is cold bent.The U bolts are bent brass rod. I intended to Loctite them into the drilled holes, but they needed to be hammered home, so I think that glue will be unnecessary. (I made 2 extra)
So, I think that those are the final parts to be made for this model. Now I need to decide about finishing the wooden surfaces. At this stage I am thinking of a dark wood stain, then a satin finish with a wood oil.
Firstly some woodworking to make the platform floor. Basic machining, drilling and screwing.
Quite pleasant to do some basic cutting on the bandsaw and thicknessing on the mill. HSS metal mills give a good finish on hardwood. It was finished quickly, and went so well that I proceeded to a task which I had been putting off, because I knew that it would be very difficult.
I made the carriage recoil stops, and installed them.
The problem was that the platform had been previously assembled, including gluing of the joints. And I was not going to break those joints for anything.
The recoilatop is on the inside of the platform slides, at the rear. Shown here above the bollard. It is recessed into the slide so only the actual iron stop is above the surface. Also, it is underneath the bracket which supports the gunner’s rear platform.
The stop bracket is about 30mm x 6mm x 2mm, and the stop protrudes about 5mm further. So the first question was how to make the rebate. The distance between the slides is only 53mm. Not much space to use chisels. And end mills could not be used. The metal surface of the slides is glued and screwed to the slides, so removing those was not an option either. I should have made the rebates BEFORE I glued up the platform. Oh well….
This is the setup which I used….
I bought some Woodruff cutters and T slot cutters at a sale some years ago. So I cut the slots with one of those. The cutter worked well, but it left sloping ends. One of the ends is hidden behind a bracket, but the other one is visible. Used the inspection mirror to watch the milling on the near slide.
So how to square up those ends. Not enough room to get a chisel into that space. Still wondering, I made the actual stops.Making the stops involved some basic milling and silver soldering. The steel nut got a bit chewed up during the slotting. It will not be visible in the final assembly.
Then, rather than squaring up the recess, I rounded the hidden corner of the stop bracket. Easy!
Drilled the holes in the stop brackets for the screws, fitted the stops into position. Now, how to drill the holes in the wooden slides for the screws? The holes in the wood were only 1.4mm diameter. And a 1.4mm drill bit is not long enough for the drill chuck to miss the other slide. To avoid the other slide the hole would be excessively angled.
So I used another trick which I have used previously. I silver soldered the drill bit into some fine (2mm OD) copper pipe….
1.4mm, 1.6mm, and 2mm drill bits given substantial extensions. I used copper for the small sizes because I had some suitably sized pipe. I had drilled the hole in the brass rod for the 2mm extension for another model.The extension meant that there was only slight angulation of the hole when drilled with a battery drill.
I will enlarge the countersink on the stops to bury the screws deeper, then file the screws flush with the stop surface. I doubt that the bit of angulation will ever be noticed. I used steel screws, because a brass one snapped off and I had to drill through the remnants. The steel screws are slightly bigger than intended, but not excessively. I had removed the gunners platform to improve the access. The area will look tidier when fully reassembled.
I am very glad that particular task is all but finished!!
ps. I have called them “stops” but that is probably not the correct term. The recoil of the carriage is reduced by the 5º slope of the slides and the braking from the compressor. The “stops” (or whatever they are called) are the final impediment in limiting the recoil of the carriage and its barrel.
Today I milled the rebates which the wheel brackets fit into. Only 1mm deep and at an angle of 15º to the base line. It went fairly well, but when I reversed the milling pattern for the reverse sides, It went a bit askew by about 0.5mm. Not much, but enough to be noticeable, so I filled the defect with wood putty.
Then I milled the 3º chamfer in the wheel brackets. Straight forward process.
Finally, with the brackets sitting correctly in their rebates I wondered how to make the bracket retaining bolts, and the wheel axle shaft.
The bolts have dome heads.
I prefer to use stainless or brass bolts, but none come with dome heads, so I considered various options. I chose to use a method which I have used previously.
I selected some 3mm stainless cap screws, and filled the head with 50% silver solder.
I needed 4 dome head bolts for the brackets, so made 6, just in case.at top is the lathe ER40 collet, which is holding a smaller ER16 check and collet, then a 5mm screw for form turning with the milling rounding over bit. It all worked well, with only 2 failures. In the above photo the turning has not quite fully formed the hemispherical head.
…And used a rounding over milling bit, held in the toolpost, to round over the capscrew head and its silver solder filling. The first screw bent during the form turning, so I placed them deeper in the ER collet chuck. A later one broke, so I slowed my feed rate. I ended up with 4 bolts.
I did the same with some bolts for the axles, but they are fully threaded, so this will be a temporary solution until I can make more suitable axles.
But you can see how the brackets, wheels, bolts and nuts will appear.
You will notice the filled hole in the carriage cheek. That was a mistake, but rather than start the cheeks from scratch again, I chose to fill the holes. They will be almost invisible when the cheeks are finished, I hope.
The axles are temporary. I am happy with the brackets.I am showing the best side here. Looks OK?
The Armstrong 80pr rifled muzzle loader at Hopetoun Gardens, Elsternwick, Victoria. One of two. On the Elsternwick guns the slides have been covered with sheet metal covers to protect them.
The carriage wheels are at the front of the carriage. They do not actually contact the slides unless the rear of the carriage is levered up a few millimetres, to assist with rolling the gun down to the firing position.
They are constructed of bronze.
On my model, the gap between the wheels and the slide would be about 0.3mm.
Today I attached the wheel brackets to the carriage cheeks (the sides of the carriage).
I had deliberately made them with a slightly large diameter, knowing that I would need to reduce the diameters after they had been fitted.
This is how I reduced the diameters…..
…on a belt sander, holding the oiled shaft in my fingers and using my thumbnail to hold the wheels in position. After a few seconds sanding, and being careful not to sand my fingers, I tried the wheels on the carriage, rolling it up and down the slide. That was repeated multiple times until the wheels were just clear of the metal slides.
The single axle will be replaced by more authentic appearing separate axles with dome heads and pins. The brackets will be let into rebates in the carriage cheeks, and tapered in their upper halves.
The Armstrong 80pr cannon on the dwarf carriage and wooden traversing platform, slides wood on metal slides. But, when the carriage and its heavy barrel (4+ tons) are returned to the firing position, there are two small bronze wheels to make the return easier.
Two strong gunners lever the rear of the carriage and barrel slightly, so the two small wheels at the front of the carriage take some of the weight, and the carriage runs forward. In fact, the return was a bit uncontrolled, so a rope was added to the rear of the carriage, thrown around the bollard at the rear of the slide, and a third gunner added some control to the return.
Today I made the 1:10 scale wheels. They are 20mm diameter, and 10mm wide. 13mm wide if the hubs are included. I spent a couple of hours with the design. And another couple experimenting with various CNC processes. Not many photos of all of this I am afraid. I learned some new V Carve Pro commands, including nesting commands using the same milling cutter, but there was some trial and error. The first two wheels took a couple of hours. The final two took only 30″.
The original wheels, and brackets.The brackets are partially recessed into the carriage cheeks. The wheels do not contact the slides unless the rear of the carriage is levered up slightly.A wheel, and brackets ready to be fitted to the carriage. The dished section was milled with a ball nose cutter.I will fit them next workshop session. The brackets need a lengthy chamfer first, as per the second photograph.
NB. these parts are not finished. Sharp edges remain. I will probably put them in the gemstone tumbler to smooth the edges.
Today I CNC milled the cams. And silver soldered them to the bearings.
The same process as making the bearings in the previous post. But much smaller.Silver soldered. Hebel base and brass block at rear to stop the parts blowing away.Magnified +++.The handle was cnc’d, but I made a mistake with the dimensions, so made another one. That is easily done with CNC. The tabs are cut with side cutters.Pins are fixed in the 4 holes around the pivot, and a “rope” 2mm diameter in the end hole. I will turn the handle over to hide the distal ding. The marks are the limits of handle travel, limited by the carriage transoms.
PS. A few days later. In a fit of perfectionistic idiocy I removed the bronze cams, and replaced them with steel ones. The originals were iron. The pins which pushed on the cams were also steel. That took about 3 hours, but now I can sleep easy.
And by the way, the compressor was working perfectly when finished. But a few days later, with a change in the weather, it is not applying enough pressure to the slides. That is the problem with articles made from wood….. they expand in humid weather, and shrink in dry weather. Dimensions changes of 3% are common, across the grain. It was probably one reason the wooden compressors were abandoned in favour of Elsworth iron compressors, and hydraulic mechanisms.
Making scale model components probably takes as much time as making full size ones. Well, with some exceptions. In each part of the compressor for example, there are as many measuring, set-up and machining actions in the model as in the full size part. Finding dropped tiny parts would take as much time as the (considerable) manhandling of the heavy full size ones IMO.
Yesterday for example, I spent about 3 hours deciding how to attach the compressor support pieces, cutting, machining, drilling and tapping the holes, then fitting them.
I use brass or bronze or stainless steel wherever possible. Not always the same as the original, but I don’t want my miniature to end up in the same condition as the originals in another 150 years. The brass tabs were placed as close as possible to the corners, but avoiding the long bolts holding the leaves together.The underside of the compressor. 10BA bolts. Wood gets grubby in the workshop. It will require a good solvent cleanup before finishing.To demonstrate the compressor location. It sits on the metal slides, and between the cheeks and cross pieces (transoms) of the carriage.The Smith’s Elevating Screw is finally complete. Here showing the pins which engage with the gear to turn the screw. The handle spins freely on the screw shaft. The hemispherical top sits in a corresponding hole in the bed plate. I am satisfied with this interpretation of the limited information available about the Smith’s Screw.
A very pleasant drive to Warrnambool yesterday, and re-inspection of the very rare compressor which was the recoil arrestor for the LowMoor 68pr cannon. And probably for all guns on the same carriage and platform, including the Armstrong 80pr RML’s at Elsternwick, Queenscliff, etc which I am currently modelling.
This is the 1861 compressor. 2 elm wood pieces, plus a repair on the right, all splits, cracks, rot and rust, and rather fragile. 4″ thick. Possibly the only one of its type still in existence. The central bronze elliptical bearing shell halves are in good condition. The iron pieces riveted to the bearing shells are rusted, but fairly intact. The rectangular pieces in the corners rest on the inclined platform slides. The central iron presumed elliptical post and its handle are missing.
I wanted to closely examine the iron riveted pieces closely to check my theory that the short straight sections are the parts which acted as the cams to close the gap between wooden leaves and release the friction from the braking action. Unfortunately the rust concealed any such evidence. But I still believe that was the purpose of these iron pieces.
So, today, I commenced making a 1:10 scale model of the compressor to fit to my miniature cannon.
The bronze bearings and attached iron cams protrude above the surface of the wooden leaves.
At 1:10 scale the bronze bearings would be less than 1mm thick. How to make them?
I CNC milled them from some gunmetal hex bar, then parted them from the bar in the lathe. I had previously made the wood leaves, and CNC’d the elliptical hole to fit the bearings. I don’t have any elliptical drill bits.… and they fitted nicely. The original bearings were screwed to the wood leaves. I intend to use Loctite. The originals were made of elm. I used a close grained Victorian Mountain Ash.
I milled the steel elliptical post from silver steel. Yes, CNC’d.
Steel post, threaded to eventually fasten the handle with pins to move the cam pieces. Handle not yet made. The pieces all fit well. The screw is temporary.
Another workshop session require to make the iron cams and the handle with pins.
After milling the rebates in the wood, I attached the bracket with the brass screws, and sanded them flat with the surfaces. Most of the strain will be on the steel screws. The brass screws are screwed and Loctited into place.
Then drilled and tapped the wood for the BA10 stainless steel bolts. It is fairly close to the original fastening method.
It took 4+ hours.
A short post. Tomorrow I am visiting the Flagstaff Hill Museum at Warrnambool, 2.5 hrs each way, to get some final details about the wooden recoil brake, the “compressor”. There is a problem with my CAD drawing of the compressor, and I am hoping that close inspection and measurements will answer my query. I will be accompanied by my expert friend Stuart for some extra perspective. The compressor will be the final substantial component to make for this model.
This is one of the few parts required to finish the model Armstrong 80pr RML cannon on a wooden carriage and traversing platform.
It is the ring which is attached to the rear of the carriage, used to control the descent of the carriage and barrel down the slide to the firing position, with a rope attached to the ring. The bracket is buried within the rear transom, and extends underneath the transom with more screws and bolts.I cut the bracket pieces from 2mm flat brass strip, using a 3mm diameter endmill.
The issue in silver soldering the pieces together was that they are quite small, about the size of my little fingernail, joined at an 95º angle, with the ring also soldered in place in the same heating session. And I did not want solder getting into those 1.6mm diameter holes.
So I screwed the angle pieces to a block of hardwood which had a 95º angle, having fluxed the edges carefully to exclude the flux from the tiny holes. I would have added typists white-out if I could have found it.
I knew that the wood would catch on fire with the soldering torch, but hoped that it would retain its basic shape until the solder solidified. The steel on top was to hold the ring in position during soldering. If the method did not work I figured that I could make an aluminium shape to replace the wood.
After soldering, I put out the fire by dunking the assembly in a bucket of water.
And it cleaned up quite well. Now to carve rebates in the transom so the bracket sits flush with the wood surfaces.
The circular cutout is to allow the end of the Smith’s Screw to protrude under the transom.
Not much to show for several hours in the workshop, but it’s better than working. And best of all the method was successful.
Another hot summer day today, so I arrived at my workshop early, before the heat set in.
First I drilled a 1.5mm hole through the Smith’s screw yoke and bracket, for the pin which completes the hinge mechanism which engages and disengages the screw handle. Sounds simple? Well, actually, my intention was insert a 1.0 mm pin, but the first drill bit broke. Now why didn’t I make that sensitive drill press when I first considered it?
So I had to disassemble the parts, and grub and poke around with a fine tungsten probe until all of the bits were out. Then set it up and drill it again. Used a 10BA bolt and nut as the hinge pin.
Then silver soldered some 1mm old drill bits into the previously drilled pin holes as the driving pins for the screw gear.
Parts fluxed, ready for heat and silver solder. I use 50% silver, with cadmium for these tiny parts. After soldering, a quench in water, brief soak in sulphuric acid to remove any remaining flux, another water wash, then the drill bits are cut to length, and tidied up. Why did I use drill bits? Because they were the only drill rod/silver steel which I had in this diameter, and it is a good use for blunt drill bits.
By this time the day was really heating up.
So, I threaded at 2.5mm some 3mm brass rod, then heated the sections where I needed to apply the bends, and made the handle. Also form turned the hemispherical head using a 2mm radius rounding over milling cutter on the lathe as described in a recent post.
The threaded post length might need to be adjusted, because I made it slightly longer than thought necessary. I have some spare length at both ends if necessary to adjust.
In position. It works even though I still need to fix the gear to the threaded post, and fix the truncated cone at the top to the post. I intend to use Loctite.and I have yet to machine a hemispherical cavity to the underside of the iron (brass actually) bed.
Another half day workshop session saw some more small parts made for the Smith’s Elevating Screw at ~1:10 scale. As close to 1:10 scale as possible, but I decided to make the parts about 20% bigger than the dimensions I scaled off the poor quality drawing, to fit with small drill bits and end mills in the tiny end of the range. The smallest end mill which I used was 1.5mm diameter!
CNC Drilling the gullets in the gear with a 1.6mm drill bit, after turning the OD of 15.9mm. I made 2 of these parts, just in case.
This is the gear after completing the gullets with the 1.5mm end mill. 3000rpm, 0.5mm depth of cut, 30mm/min feed rate. (metal working is not great for hand beauty)
The Smith’s Screw square thread, yet to have a hemispherical head turned after sawing off the excess length, the brass half cylinder nut, the gear, the yoke and the shaft bracket. A hinge pin will be inserted first, then some relieving of the hinge edges. The yoke and shaft bracket were CNC’d from 3.5mm brass plate.and a handle to be added, and a restraining collar. Oh, and the 3 steel driving pins to be silver soldered in the yoke holes.
One more session should see the Smith’s Elevating Screw completed.
Did you notice that I have modified 6 details since drawing this?
Unless you have one of these resin printers I suggest that you close this post and look at something of greater interest.
One problem which I encountered with my AnyCubic Mono X 3D printer, was that it was often difficult to separate the print from the base without damaging the print due to excessive adhesion. I have changed the print settings to reduce the initial layer UV exposures to 16 seconds which has helped somewhat, but I decided to try using a magnetic plate. A magnetic plate worked really well on my filament printer, and I was hoping for a similar result on the resin printer.
So I purchased another aluminium base, and a 3M stick on magnetic surface. I could have used the original base, but that would have committed me to using only the magnetic plate surface. Having a second base leaves my options open.
The base which I purchased looked similar to the original, but I noticed that it was not flat. In fact it had a concavity of approximately 0.25mm over its length. Also, it was missing the rather distinctive AnyCubic patterning in the aluminium surface which I think was a reason for the high adhesiveness of the original plate.
So I spent about an hour sanding the base with 200g sandpaper on a surface plate, and finishing with 600g emery paper, also on the surface plate. After that I could not pass a 0.003″ feeler gauge under the edges of the plate. Not dead flat, but should be close enough.
The surface plate, emery paper, and printing plate.
I had watched YouTube accounts of other AnyCubic Mono X owners using these magnetic plates, and finding that the extra thickness caused by the magnetic plate (2.6mm) was too great for the levelling mechanism to function. Various work arounds have been used, including moving the position sensor, and 3D printing a spacer for the sensor, to gain the extra 2.6mm.
My solution? With a milling machine waiting to be used?
The printing plate bracket.
I milled the screw slots 3mm longer, and milled 3mm deep rebates along the edges as shown above. Admittedly, the same result could have been achieved with drilling and filing.
The cost? $AUD40 for the new printer plate, and about the same for the magnetic surface.
When the Armstrong 80pr barrel was mounted on a wooden carriage, the angle of elevation was fixed by the weight of the breech resting on a wooden wedge shaped item called a quoin. The quoin was marked with graduations to correspond with degrees of elevation.
To change the elevation, the breech of the barrel was levered using the steps of the carriage cheeks as a fulcrum and the quoin position was adjusted. The trunnions of the barrel were placed forward of the centre of gravity, and the weight that gunners had to lever was considerable.
The angle of the wedge of the quoin was important. Too great and it could shoot out backwards when the gun was fired, and risk injury to the gunners. Too shallow would make it too long or restrict the range of elevations.
Fine adjustment of the angle of elevation was managed with a screw mechanism called a Smith’s Screw, introduced ~1860.
My CAD drawing. The bronze base is reasonably accurate. The other parts are based on the diagram below, or inferred.
I am currently making a Smith’s Screw for my 1:10 model. I must rely on old drawings of the Smith’s screw, because I have been unable to find a single example of a museum specimen anywhere. And the Smith’s Screws have been removed from all of the existing original wooden carriages. When not in use for actual firing, the screw and handle and gears were removed and placed in storage, along with the gun sights. Who knows what happened to the Smith’s screws when the guns became obsolete.
Some dimensions can be inferred from the base, which sometimes does remain in the original carriage, and from the rounded cavity in the iron pivoting slab which the screw supported. There are very few original wooden carriages, and I have been fortunate to find a handful in Victoria. I am told that they are exceptionally rare in UK, having been broken up when the guns became obsolete. Unfortunately, the drawings which I have found are of poor reproductive quality, and have no dimensions apart from the diameter of the screw (2.25″).
Smith’s Screw on the right.
One design feature of which I am reasonably certain is that the screw itself would have been a square thread. Acme threads were introduced in 1894, and replaced square threads in most applications because they were easier and cheaper to manufacture, stronger, and when the nut became worn it could be adjusted to take up the wear. Square thread nuts had to replaced when they became worn. The only downside to the Acme threads was that there was more lateral pressure on the nut, and greater friction and resistance to movement.
29º included angle is “Acme”, 30º is “trapezoidal”Acme or square? Can be difficult to decide. Will it make any difference at 6mm diameter? It certainly makes a difference when making the thread.
So, I have been on a learning exercise to make a square thread. So far I have had about 6 failures. Maybe more. I can see why the square threads are more expensive than the Acme threads.
I had decided to make a 5mm diameter screw. A bit smaller than the 1:10 scale of the 2.25″/57mm original. Actually, 6mm would have been closer. (thinking). It needed to be 1.5″/38mm long. The pitch is unknown, but I had a tungsten cutter which appeared to have been ground for just such a purpose, with a width of 0.8mm, and therefore a pitch of 1.6mm. So the cutter determined the pitch. I have a CNC lathe, so I could decide on any pitch without changing gears. For example I could choose a pitch of 1.6mm, or 1.61mm. Whatever. But to be a square thread the thread depth should equal half of the pitch.
The next problem was with my CNC threading software. Mach 3 has a simple threading “wizard”, and I tried it on my CNC self converted Chinese lathe, which works fine for most applications, but the lathe’s shortcomings (lack of toolpost rigidity mainly), and use of stainless steel rod, gave poor results, then caused the cutter to snap.
So I switched to Ezilathe. Several problems due to my inexperience with square threads vs. conventional 60º threads and a software bug, prompted several calls to the software author, who resolved all software issues without much ado. (thanks Stuart)
But, I was still not getting good results, so I tried my Boxford CNC lathe. It is a beautiful little lathe, but with one serious fault. The tailstock is horrible to use. It is a real fiddle to install, limits the movements of the cross slide/toolpost, and worst of all I did not have a suitable morse 2 centre. I suppose that I should have taken time out and made a dead centre. But I didn’t. Wanting to see some results I pressed on.
With Ezilathe now working well, I decided to practice the square threading using 5mm brass rod. Without a tailstock the 40mm protrusion from the chuck was too much, and the rod bent. Sharpened the cutter, used minute depth of cut (0.02mm), and reduced the protrusion to 22mm, to make a 20mm long thread. Ahhhh. Looking better.
Now to try it with the steel.
That also worked well! A very nice square thread 20mm long, and the rod barely deflected at all. Copious lubricant being brushed on at every pass. 300 rpm. 0.02mm DOC. Sharp cutter.
Now, the rod duly square threaded is required for the screw, but 20mm was a bit short. It really needs to be a minimum of 30mm of thread. 38mm would have been ideal. And I need a length for the screw itself, and another length to make a tap to thread the nut. So I tried a 30mm protrusion. And heard a “click” as the cutter snapped. I think that the deflection causing chatter was the cause. Or maybe the discolouration of that end of the steel indicated that I had used it previously during silver soldering. Maybe I had hardened it.
So I stopped there to lick my wounds, went home and slept on the problem.
Next session I will: 1. make a dead centre for the Boxford, to support longer stick out. 2. Use silver steel instead of stainless steel. It will harden better for the tap, and might turn a bit easier. 3. Use 6mm rod instead of 5mm. For extra rigidity. 4. Make the thread 5mm longer than essential, to keep the cutter clear of the tailstock. I will turn the diameter of the extra 5mm length, down to 5mm diameter, to minimise the impact of the cutter plunge.
Oh, and by the way, I have been making left hand threads. The Boxford has a rear toolpost, and I forgot to invert the cutter which is required to reverse the direction of the chuck to make a right hand thread. I do not know what handedness the original thread had. But right hand is more common generally.
And if all that still fails I will make Acme threads. They will be easier, and at the scale I doubt that most observers will pick the difference.
Next day, next workshop session.
I decided that tailstock support was essential, so I went to my Colchester 2500 Master lathe, and plugged in the 2mm pitch settings. Easy. The tailstock was introduced. I made some right hand threads, on 6mm silver steel, no problems. Just time consuming. Had to regrind the 1mm width cutters several times, but eventually I had 2 reasonable lengths of square thread. One for the Smith’s Screw on the cannon, and one to make a tapping tool.
I machined a taper on the tapping tool, then used a Dremel with grinding wheel to produce the reliefs. Heated the tool to dull red heat and plunged it in cold water. Then gave it some slow heat to anneal it. It was still able to be filed, so the hardening process had not worked well. But it was to be used for only one tapped brass nut, so I accepted it, and proceeded.
The tap. It will the first and last square tap I will ever make. My eyesight was just not good enough to accurately grind the reliefs.
Cutting the thread in the brass nut was not easy. I needed several revisions of the thread cutter, using the Dremel with a small grinding wheel.
This is the brass nut on the square thread steel. Not as tight as I would have liked, but OK. Useable. 6mm diameter. 2mm pitch.Fitting the nut to the base required some further relieving with the Dremel but there were still some tight spots, so I used a method from the past. Gumption.
Gumption is a kitchen cleanser which has a mild grinding action using rotten stone. It lasts only a few strokes, then disappears. But it worked brilliantly, and the nut now fits perfectly in the base. The excess Gumption just wipes or washes off.
So that was a day in the workshop. Not much to show. Maybe I should have spent the day with wine, women and song. It’s OK. SWMBO does not read these posts.
Next session to finish the threaded post with a hemispherical head. (just fantasising about the W, W, and S). Then the cog, handle and corresponding hole in the “iron” support.
This is my CAD drawing of a Smith’s screw, which was used for fine adjustment of the barrel elevation of cannons on wooden carriage/platforms. The pivoting nut sits in the base. The threaded shaft is turned by the cog near the top which is turned with the iron lever which has protruding pins.
I started this mechanism for the Armstrong 80pr gun model today, by making the bronze base.
There were 4 components of the base, which were joined with silver solder. I could have printed the whole base and cast it in bronze, but I had nothing else to cast so decided to fabricate it with basic machining.
The 4 components. The bearing surface is bronze, the rest are of brass.Squared up a lump of bronze, then used a ball nose cutter to make the rounded channel.Carved out the desired bit…And silver soldered the 4 components. Not very pretty at this point. But with some filing and sanding it finished looking quite respectable.
Then to machine a recess in the posterior transom.
I did not want to make a mistake here, so did an air cut to test the CNC programming. First a shallow cylinder, then a deeper rectangular hole.I spent an hour or so filing the part to make it fit into the recess. It was a neat fit, so pressed it into position.A match to hold the “iron” quoin support in position for the photo.
Next session to make the cylindrical nut with a 5mm acme thread, and the matching threaded post.
I have made an appointment to see the original compressor unit at Warrnambool in a week, so I am deferring making that final component until I have checked some dimensions.
Ageing eyes require stronger glasses, longer arms, and acceptance of less than perfect results. However, this fault was not due to my deteriorating eyesight, but poor judgement.
I was drilling screw holes in the trunnion bearers. The bearers were tightly held by the dome head bolts so I drilled the brass and the wood together, with the carriage held in the milling vice. Unfortunately it was not held well enough, and shifted, causing the above.
So, what to do? Start again and make a new trunnion bearer? That would take maybe half a day. Or just fill it?
Filling it with copper coloured epoxy was quick and simple. If anyone notices the filled hole I might remake the trunnion bearer one day.
In the photo above, note that I have made the gun sights.
Looks a bit rough at this magnification. 10BA locking screw. 2mm diameter shaft. I have never been able to see an actual original, but this pattern is based on an old diagram of a tangent sight of the period. The shaft would have been calibrated for distance. The front sight. The sights were installed for firing, and removed for storage. In order that they are not lost from the model I have glued them in position. The machining marks are a bit ugly, but consistent with the actual finish on the full size barrels.An interesting test. The trunnions bearers holding the weight of the barrel being held upside down.
The barrel trunnions sit in bronze bearings which are held in place with screws, and under the heads of the large carriage bolts shown above. Land based “garrison” guns, like the ones which I am currently modelling, often do not have trunnion caps, relying on the weight of the barrel and the slightly deeper bearings to keep the barrel in place during firing. Naval guns always had trunnion caps to avoid the “loose cannon” disaster on board warships.
The round pins under the flanges are actually rivets, placed with the intention of preventing splitting of the carriage wood in the trunnion region.
I had turned some bronze to size to fit the trunnions and the carriage cheek cut outs. Once before I had cut the entire trunnion bearing and its flanges from solid brass, but for this one I decided to cut the flanges from 1.6mm sheet, and silver solder them to the round section.
The first issue was how to cut off the unwanted top section.
I turned a mandrel from aluminium and pushed the bearing cylinders into place…
and marked the segment to be removed.
The cross definitely identifies the part to be removed.
and milled away the unwanted bits. The sacrificial aluminium mandrel prevents distortion from holding the thin cylinders in the milling vice.
checking that they will sit correctly….a rebate will be made in the carriage cheeks so the flanges sit flush with the cheek tops.
Then silver soldered the flanges using a mini oxy-propane torch. The soldering hearth is made of Hebel blocks, which are cut fairly flat and accurately. The back block is to prevent the light components from being blown out of position by the gas torch.
After some sanding on a flat surface, and a check of the parts on the trunnions to exclude distortion, all is looking good.
Next session I machined the rebates
Some shaping of the corners with a Dremel to fit the solder.The finished result.
And I have added some more eye bolts…
But there was a problem with the eye bolts in the platform…Nuts on the inside of the slides prevented full movements of the carriage. On the originals, these nuts were buried, with nothing protruding. So I had to cut some pockets on the insides of the slides. I had not anticipated this problem when I bolted and glued the platform, and I really did not want to break it apart to make the pockets.
So, to cut these pockets in this very tight space, I made a special tool. Fortunately there was a corresponding hole on the other slide.
The finished pocket with the buried nut.This cutter sits between the slides. After that, the 3mm driving rod is screwed into the base of the cutter through the other slide, and the pin at the cutting face is placed through the side to be cut. As you saw, it worked well. Mild steel, I did not bother hardening it, and it made the 4 cuts without any problems.A bit rough but it did the job well.
So that is where this job has progressed to. Still to be made are the Smith’s elevating screw, the compressor, the sights, the quoin. And then the surface finish.
The 80 pr muzzle loading cannon was supplied to the colonial government of Victoria on a wooden traversing platform with a 5º slope.
I assumed that the slope was the means of absorbing the recoil.
The later iron platforms (from about 1875) had a 4º slope and hydraulic recoil control.
But, I was recently informed that there was a wooden “compressor”, which acted as a primitive brake, to reduce the distance of the barrel and carriage recoil. And that there was a compressor at the Flagstaff Hill Museum, Warrnambool, Victoria.
In fact I had previously seen the compressor, but neither I, nor I suspect the museum staff, really understood then how the compressor functioned.
Using Victorian Collections photographs published on the web, my own photographs, information from “The Artillerest” Peter Webster, some old drawings of wooden carriages and platforms, and a Google book “British Smooth Bore Artillery” by David McConnell, and a fair bit of deduction, I think that I have finally worked it out.
Firstly, the Victorian Collections photographs…
The compressor sits between the slides, with the rectangular iron tabs resting on top of the slides.The elliptical central hole is filled with an iron elliptical post with a long handle attached to the top. When the handle is pulled backwards the cheeks are pushed outwards by 1/8″ 3.2mm, acting as a brake. The tapered iron bits had me stumped.My drawing of the compressor with the brake applied. From above. When the handle is pushed forward, the gap between the cheeks closes and the brake is released. The pins push on the tapered outer iron cams to ensure closure of the cheeks. Ahhhh!From below the compressor, with brake applied. The handle has a square drive in the square hole. A rope is tied in the distal handle hole.
Now to make one at 1:10 scale.
P.s. reader Jeff sent me some photos of a recoil control system used in 19th century USA, where a large metal screw clamp was utilised in these rifled muzzle loaders
I had a phone conversation with Peter Webster, “The Artillerist”, yesterday, after I emailed him about the recoil control compressor which I had photographed at Flagstaff Hill, Warrnambool.
the very rare compressor. The loose metal bits on top are not part of the compressor.
I could not see how it could fit into the carriage or slide of the LowMoor cannon, or how it functioned.
Peter, who has a passion for Australian garrison artillery, 1788-1950, and has encyclopaedic knowledge on the subject, had seen this object at Warrnambool almost 20 years ago, realised what it was, and subsequently wrote a report for the museum. The compressor is classified as being extremely rare, most having been removed from the guns, probably to remove the gun metal components for scrap.
Peter explained to me that the flat, rectangular compressor sat between the platform slides with the metal corner tabs resting on top of the slides and the centre join of the compressor located along the centre line between the slides. The front and rear surfaces fitted between the cross members of the carriage.
The central hole was almost vertical. The hole is elliptical, not round. Sitting in the hole was a neat fitting elliptical post, which had a handle which protruded out to the right hand side between the carriage and the slide. When the handle was pulled, the post rotated and increased the separation of the 2 halves of the compressor, pushing them against the sides of the slides, as a brake.
Peter was sure that all carriage/platforms of this type would have been fitted with these compressors, until the wooden structures were replaced with the iron types a decade or so later.
So clearly I will have to make a scale model of the compressor for my current model.
This is a modified version of the carriage and traversing platform. It is the best drawing I could locate which shows the compressor insitu. Note also the central pivot and its large cross beam, which is bolted to the slides with the vertical bolts I had wondered about at Elsternwick. Peter told me that the Elsternwick guns would originally have been fitted with pivots, but removed due to being damaged during firing.
Thought that you might be interested in some more photos relating to RML’s.
That barrel could be an 80pr Armstrong, 3 meters long, which would make the lathe about 8 meters long. Note the date, the taper cutting mechanism, and the fact that they did some external turning with the trunnion ring insitu. This is said to be the recoil controller from the wooden carriage/platform which is outside the Maritime Museum, Warrnambool. It is apparently an exceptionally rare item. Not on display. Shown to me because I asked questions about the cannon. I could not see how the recoil mechanism would have been fitted or functioned on the particular cannon. Picture of the Warrnambool cannon on its wooden carriage and platform follows. The loose metal objects on top are not related to the recoil mechanism.The preserved, protected, and unrestored condition is very useful for modelling. LowMoor 68pr SML. 1861.I have possibly shown this photo in a previous post. It is the 1866 80pr Armstrong RML on wooden carriage and platform at Fort Queenscliff, 30″ drive from my home. Missing the Smith Screw, sights and gunners side platforms, but otherwise in reasonably complete condition. No evidence of a rear gunners platform. Front left wheel bracket needs some attention. and just to complete the photo collection of 80pr’s on wooden carriages and platforms, I revisited the Elsternwick cannons recently to get some more measurements. Early evening photo. Note the bolts hanging under the slides. They do not exist in any of the old drawings or photos. Maybe this one had a pivot support originally. Some of the very early platforms did have pivots, but they were removed as being unnecessary, and liable to damage when the gun was fired. Also note that none of these guns had trunnion caps, which were considered unnecessary in garrison guns. The trunnions do however sit slightly deeper than half way in the carriage cut outs.For a bit of perspective I add this photo of manufacturing a 16″ barrel in WW2. USA factory.
We are having a La Nina summer. Relatively cool and wet. Humid. But, it is summer, and week long spells of over 30 degree centigrade days are expected, even in a “cool” summer. Today it will be 33c with high humidity, and those are not factors consistent with a pleasant workshop experience. So I will stay home and plan ahead how to make several components for the model Armstrong 80pr cannon on the wooden carriage and slide.
One item is the elevating mechanism for the 4 ton barrel. Several readers have helped with information about the mechanism, which I now believe to be a “Smith Elevating Screw” which adjusts the level of a heavy hinged iron bar, on which sits a wooden wedge called a “quoin”. The breech of the barrel sits on the quoin. The quoin is the coarse adjusting component, the screw is the fine adjusting mechanism.
This is the carriage and traversing platform which I am modelling at 1:10 scale. The barrel is an older smooth bore muzzle loader, but the dimensions of the carriage and platform seem identical to those of the 80pr Armstrongs at Elsternwick which I am modelling. The screw and quoin and iron bar are at the rear of the carriage.
Another 19th century drawing of the wooden carriage and platform, with a 110pr breech loading barrel. Also showing the Smith’s elevating screw.This is the only picture which I could find with any detail of the Smith Elevating Screw.….and this is a 1:9 miniature Smith Screw, made by Jefenry for his Armstrong 110pr breech loader, and whose videos I have shown in an older post. Those You Tube videos are really interesting to watch. Just do a search on “Jefenry”. These pictures are very useful to me. Thank you Jefenry!And finally, a couple of recent photos of progress on the model to date. The Smith’s Screw fits into a half cylindrical nut which sits in a bronze enclosure within the rear transom.
I needed to add some substantially strong rings to the slide of the Armstrong 80pr on the wooden chassis. These rings are the attachment points of the blocks and tackle which are used to point the cannon in the direction of fire. i.e. the traversing mechanism.
Scaling off photographs and drawings I determined that the rings had an o.d. of 100mm, and an i.d. of 50mm. i.e the material was about 25mm diameter.
I had made some rings for a previous project, and had some of the material left over…
But, when I cut off the coils to make the rings I decided that they looked too spindly.
So I annealed some thicker rod which was 2.5mm brass…
… and wound it around a 5mm steel post….….cut off the individual coils with heavy side cutters, and straightened them in the vice.Then positioned them on an aerated concrete block to some 3mm all-thread….and silver soldered the rings to the all- thread. The lump of steel is just to keep the bits in position during soldering.Drilled the slide beams after careful measuring, 3mm tapped as deep as possible, then completed the tapping through the 30mm beams with a long length of 3mm all-thread.Screwed the eye bolts into position, and locked the other end with square nuts. Eventually the square nuts will be buried in the beams.No where near finished, but looking more interesting with some bling bolted in place?
Just to remind you that this is what I am modelling, at 1:10 scale. An 80pr Armstrong rifled muzzle loader, on a wooden carriage and slide. This pair is at Hopetoun Gardens, Elsternwick, Victoria.
I had imagined that this wooden chassis would be a relatively simple, quick build. The following photos show what I have accomplished in the last 3 days.
The gunner’s platform, supported by steel angle iron brackets, and the wooden “bollard” (I do not know what it is really called) which is used to wind a rope, and control descent of the cannon carriage down the slide to its firing position. And the odd metal bent rod bracket with the loop. I do not know what its function is. Does a reader know?The underside. The gunner’s platform brackets were cut from some galvanised rectangular section tubing, then bent after heating with oxy-propane. Not perfect, but OK. The stainless steel bracket between the slides was cut from 1.5mm thick sheet and cold bent.
These little parts are very time consuming, but oddly satisfying to make.
And meanwhile, my friend Stuart has once again used his 30 watt fibre laser to engrave the barrel markings.
Top is Queen Victoria’s cypher, with the Order of the Garter motto. Then the site of the vent/touch hole (which will remain as a mark only), then the barrel proving marks, and then the weight of the barrel in hundred weights, quarter hundred weights, and pounds. (just over 4 tons). At bottom is a barrel centre mark. It lines up with another one on the muzzle.
On the left trunnion R.G.F. for Royal Gun Factory, the 24th barrel of this pattern made, and the year of manufacture. Some more polishing will improve the appearance and sharpness of the lettering.On the right trunnion, the barrel centre line (horizontal), and trunnion centre line. Again barrel number 24.And, this from reader Richard, who sent me this photo of an exquisite scale model studded projectile and trolley. Studs were prohibited from the Armstrong 80pr’s because they caused rapid wear of the bores.
Actually, the wooden slides were used on other British garrison cannons as well as Armstrongs. For example, at Flagstaff Hill, Warrnambool there is a 68pr LowMoor mounted on a wooden slide, which is identical to the slides used for the Elsternwick Armstrong 80pr’s. And I have a drawing of a breech loading 110pr which was also mounted on an almost identical slide. The only differences were in the carriages, and those differences were minor, depending on the diameter and weight of the various barrels.
So I have used measurements from several slides, located at Port Fairy, Warrnambool, and Elsternwick. The Warrnambool slide is unrestored and badly rotted in some places, allowing inspection of the interiors of the big longitudinal beams. The Elsternwick slides have been restored, painted, and have metal protective covers, which conceal details of the metal strips on the tops of the slides. The Port Fairy slides have been extensively and expertly restored.
And there are always compromises to be made when scaling down structures by a factor of 10. Fasteners for example are only approximately the scale dimensions.
Here are some pics of progress to date on the slide…
The metal strips are stainless steel. Not authentic but should polish nicely. 30 countersunk screws per side. I superglued the slides in position, then centre drilled, drilled and countersunk the holes. Getting the countersink depth was tricky and required a lot of trial and error on each hole. Then I filed any protruding bits of screws flush with the slide surface.
To shape the stainless steel strips, on Xmas Eve, I roughly bandsawed them to shape, then milled the edges to end up with 23mm wide strips, 480mm long. The steel is only 1mm thick, so holding it for milling required some planning. Guillotine or laser cutting would have been preferred, but not wanting to wait until mid January for a pro shop to cut it, I did it myself, using 2 bits of straight hardwood to hold the thin stock in 2 identical vices on the milling machine.
On one of the bits of hardwood I made a 23mm deep cut on a face of the wood, and rested the thin stainless steel on the lip thus formed. Then ran a sharp milling cutter along the surface of the wood, cutting the steel to size. That worked fairly well. As you can see, I removed about 10mm width of the steel in one run. Checked the dimensions, remounted the strip in the bits of wood, and finished the edge milling. Yes, I had to file the edges to remove the sharps. Drilling the fastener holes, after supergluing the strips into position. The large hole is as in the originals, to allow access to the wheel bracket bolts.The wheel brackets are finished, and bolted into position. Wherever possible I am using brass, bronze or stainless steel. A few more parts to be made and fitted, including carriage stops, a wooden bollard, gunners platform and tackle block rings. Then to decide about painting-finishing.The wheel brackets are attached by a bolt which passes right through the longitudinal beams, to be secured with a round nut at the top.
Today I turned the chassis wheels, and the axles, washers, and pins.
First I tried to turn the wheels from some stainless steel shaft, but it was too hard, and destroyed HSS and carbide tips.
So, I changed to some free machining steel. A lot nicer.
A steel wheel, stainless steel axle, and brass end washers.The washers have a curved face. I could have CNC’d the curve, but I used a method which had previously worked well. Using a milling bit, designed for milling a rounded edge. But works incredibly well when supported in the lathe toolpost.Then parting the washers.8 washers required. The lathe spindle had to be run in reverse. Quick, and excellent finish.
Then the axles were drilled for the retaining pin, and ground to length.
Next session in the workshop I will make the wheel bracket supporting bolts.
For my previous model Armstrong 80pr cannons I made the iron carriage and slides using metal casting of 3D printed PLA filament for the complex castings. The results were OK, but I was not satisfied with the surface finish.
So, I bought a resin printer, and I have been very impressed with the results of the resin prints.
But, to date, I have been unable to get any castable wax resin suitable for the resin printer, with which to make the bronze castings.
So, I decided to revert to traditional machining methods, using reductive technology. Milling, lathe, etc, removing brass chips from bar stock to end up with useable parts.
This is what I am trying to make at 1:10 scale.
The wheel bracket appears to be made of cast iron. Possibly the wheel also, but it was probably turned in a lathe.These are the brackets which I have milled and turned from 38mm brass bar stock. Not quite identical with the originals, but close enough I have decided.Billets cut to length, with an allowance for holding in chuck. OAL 50mm.The external shape was CNC’d.The wheel slot was cut with a 3.5 mm thick slotting saw. 3 cuts to get the full 9.5mm width. The axle holes were spotted and drilled.
Then, I pondered long about how to remove the 20mm of stock which was allowed for the chuck jaws. I realised, too late, that I should have allowed another 10mm or so, because the parting line leaves too little to be held in the lathe chuck while parting.
So, I came up with this work holding solution…..
I drilled the hole in the bracket which will eventually house the mounting bolt on the model. 5mm diameter. Then drilled a 5mm hole in a piece of scrap, and bolted the 2 pieces together.
Actually, 5mm allthread is not much to hold a 36mm diameter piece for parting. So the thread was nutted and lock-nutted at each end. And torqued as tightly as I dared.
Holding the bolted extension in the 3 jaw, then slowly parted off the bracket. I stopped at 7mm, so the bolt holding the parts together did not crush the parts together and jam the parting tool.Removed the bolt, and hacksawed the bracket from the bar. Then some belt sanding and finishing on a flat plate.
After parting the first part by hand winding the cross slide, I became more adventurous with the next three. Made sure that the gibs were tight, the carriage locked, and setting the spindle at 500rpm, used the power feed to do the parting automatically. With plenty of coolant-lubricant (my home made mixture of olive oil and kerosene.). But still finishing with a hacksaw.
With end result shown in photo 2. All good.
Next to make the wheels and axles from steel. Those brass bar offcuts will go into the “might be useful oneday” container.
So, I got a container of basic grey printer resin with my new Anycubic Mono X resin printer, and I have been learning the basics of resin printing. Lots to learn. Not like filament printing at all. Lots of failures, but getting there.
Almost at the point where I would like to make a metal casting, using the lost PLA/resin/wax method.
1 litre of basic grey resin costs about $AUD40.
On YouTube, the experts seem to be using special resins suitable for casting. For example Sirayatech Cast Resin. Costs about 3 times as much as the basic grey resin when postage from US, and taxes are added in. And about 6 times as much as filament on a weight basis.
But, I wondered, can basic grey resin be used for casting? It is MUCH cheaper.
So I performed a little experiment.
I placed two small PLA filament printed objects in the burn out oven, with a resin printed object of about the same size. And progressively turned up the temperatures.
On the left is a basic grey resin printed wheel bracket. Middle and right are filament printed PLA wheel and wheel bracket. All in the burnout oven. At 250ºc not much is happening. ( a quick door opening, photo, and door close.)At 350ºc the resin object looks unchanged. The 2 PLA objects are melting.Not a good photo, but at 430ºc the resin object is black, but retains its shape. The PLA objects have vapourised and disappeared.This is the resin printed bracket after 15-20″ at 450ºc. It has left a shell of carbonised material. The PLA printed objects have disappeared. You can still see the bracket shape in the ash.I let it cool down, and then crumbled it in my hand.
At the end of this simple test, I hesitate to title it an “experiment”, I have to conclude that basic grey printing resin is totally unsuitable for using as a “lost plastic” in metal casting. It leaves too much carbonised ash which would be incorporated into the melted bronze/aluminium.
OK. so I have ordered a litre of the expensive Sirayatech Cast resin.
Actually, I bought it myself. 71 years of experience has taught me that Santa has little clue what I really like. And although it was justified on the basis of being an Xmas present, it did not arrive until New Year’s Eve, thanks to Australia Post. It sat in a clearing facility for 10 days, about 5km from from my house. They were too busy to bring it the 5km. Maybe APO executives are still really pissed off at missing out on their Rolex watch bonuses this year, or whatever.
Anyway, it did finally arrive, and I enjoyed unboxing the bits, and reading the instructions.
IT is a resin printer. An Anycubic Mono X, which converts liquid into plastic objects, with an incredible degree of accuracy and surface detail. 0.05mm layers, which are invisible to my eyes.
On the left is a semi automatic alcohol washer, and an ultaviolet hardening light, which was strongly recommended by various users. After 2 days of use, I am SO glad that I paid the extra $$ for it.
So, why have I moved from a filament 3D printer, to a resin based printer? And paid over $AUD1000 for the gear? (if I had waited until after Xmas I would have got the gear for $100-150 less).
Well, the promise of greater surface detail, absence of visible printing lines, waiting hours rather than days for prints to finish for starters. And it is newer technology, which usually means better. But not always. And the fact that several johnsmachines.com readers have recommended the technology for my cannon parts was quite influential. (thanks guys! You were right.)
There are a few downsides, compared with filament printing.
The liquid resin does have a chemical odour, a bit like rotting fruit, but frankly, it is not too bad. Even SWMBO has not objected to my initial prints being conducted on our breakfast table.
And the resin is said to be toxic. Masks, gloves etc recommended. But I wear neither. I do wash my hands frequently, and I wipe any drops/spills quickly. If I start twitching or talking rubbish or scratching a rash, you will know why.
And the maximum print size is smaller than possible from my filament printer. That had a maximum print size of 300x300x400mm. The MonoX resin printer has a maximum print size of 200x125x245mm. That means that any larger models will need to be split into 2 or pieces, and the parts joined later. But the parts are so accurate, that joining them to make larger models is a real possibility. Bigger resin printers are available, but not at this entry level price.
Resin printing is a bit messy. And cleanliness is essential to get good results and to prevent damage to the machine components. So there are a lot of paper towels, tissues, and alcohol. And I mean 99% Isopropyl Alcohol. I bought 1 litre from Bunnings which cost $AUD29, only to discover that the cleaning machine requires 8 litres. I quickly discovered a firm which sells 20 litres for $AUD100 posted, and bought a container (at $5 per litre).
And what do I have to show you so far?
Well, this is the standard test print. It worked at the first attempt. It is quite small, and I used the default settings. Note: no visible printing lines, no lumps or bumps or support marks. Pretty good!
Then, I had a few frustrating failures. Parts which I had designed, refused to print properly. So I went online to the MonoX users group on Facebook, and I got immediate helpful advice, which did not appear in the official operators manual.
For example, my prints were so strongly attached to the build plate, that I had to destroy them to get them off.
The advice? 1. freeze the build plate and attached parts in the freezer for 30″, then heat them under hot water. They separated easily. 2. reduce the intensity and duration of the UV light to 80%, and 20 seconds (rather than the default 40 seconds). Problem solved.
Test prints, showing incredibly fine detail. And showing that 2 second burst of UV is optimal.The level of detail is incredible. The fuzziness is my camera, not the print.
I am currently printing a cannon wheel bracket, as a test. With 1mm wall thickness. I am not interested in making plastic parts, except to use them to cast bronze or aluminium parts from them. The next test is to burn them in the potters oven to see how much ash remains.
Photo to be added…..
First actual part! 36mm diameter, 1mm thick walls. Drain holes added will be plugged with wax before burn out and casting. How perfect is that surface? (it is a wheel bracket for a wooden slide under an 80pr RML Armstrong cannon.)
This is what the casting looked like after I had removed most of the investment, and turned a flat surface on the top of the casting.
I was surprised that the levering pins, and the big thread came out much better than the simpler flat surfaces. That might be because I had concentrated on those areas with the painted on investment slurry. And also because that end was at the bottom of the pour. That end got the first, most liquid melt, and the pressure of the melt above.
Turning the ragged end where the bronze was short.It IS sort of interesting, no?
Having decided that my casting equipment is inadequate for this this size and weight object, I do not intend to have another attempt at making a 1:10 bronze Ottoman bombard. Plus, even this sad 3/4 complete component is VERY heavy. I would not enjoy carrying the full size 1:10 model.
The only question remains, what will I do with the above failure? It could join my gallery of failed parts (like the crankshaft of the triple expansion engine, which had a single incorrect dimension). It is useful to occasionally survey this gallery. It does motivate me to measure twice, cut once. Or it could become a very heavy and expensive door stop. Or I could drill out the bore and use it as a specimen flower vase. Or I could cut it up, and use the bronze in future projects. Maybe I will just sit on the decision for a while, unless any readers have any persuasive suggestions.
I am reminded of one of my late father’s aphorisms. “He (or she) who never made a mistake, has never made anything”.
This project was put aside when I broke some ribs unloading the melting furnace which I had borrowed. Each of the 2 halves of the bombard weighed about 8 tonnes in the original, and in my model will weigh about 8 kg each.
These 8 kg parts will be the biggest which I have attempted to cast.
I am using the lost PLA method, having 3D printed the parts in PLA.
Today I attached the PLA breech to a PLA pouring funnel (also 3D printed), and poured the investment medium around the part in a 5″ steel cylinder.
First I repaired the PLA part, where it was a bit ragged. Poured some melted wax where there was a deficiency due to unsupported overhang during the 3D printing process. I deliberately overfilled the area with wax. The bronze in that area will require some turning to get the eventual correct thickness. Melted the wax with a soldering iron.Glued the breech to the 3D printed funnel, also using melted wax. All of the PLA will melt and burn out during the “burnout” process in the potters oven. That is a lot of PLA to burn out, so the windows will be open.
In order to minimise the possibility of air bubbles sticking to surfaces and corners, I painted the entire model with investment, before positioning it in the casting cylinder, and filling it with investment slurry. It will set overnight, and I will commence the burnout in the morning.
Fingers crossed for the pour late tomorrow afternoon.
It is now the next evening. I am despondent.
I woke early, and when I arrived at the workshop at 7:30am turned on the potters oven, and placed the cylinder containing the PLA model and investment medium inside. (Problem #1.) The cylinder was too big to sit vertically or horizontally, so I placed it diagonally. It was awkward, and I was concerned that the bore piece, being supported only at one end, might break free. It did. (Problem #2.) Started the burnout cycle at 250ºc, slowly increasing to 750ºc over 8 hours.
While that was happening I set up the melting furnace, gas cylinders (3 of them), tongs, bucket of water, face masks, gloves, aluminised apron, etc outside. It was going to be a warm day. Unfortunately it was also windy. Not ideal.
The furnace (centre), gas cylinders rear, dry sand tray front. Bronze ingots weigh 12kg. I had predicted that the casting would weigh 10kg.
Stuart arrived, and he checked his furnace. We lit it to pre warm the furnace and crucible. (Problem #3.) The crucible fitted in the furnace, with little space to spare. Just enough for the crucible with its tongs to fit. Stuart commented that it looked very big. It was, I answered “a 14kg crucible”. When the 12kg of bronze eventually melted it only half filled the crucible. It was not the size which I had ordered. It was too big, and restricted the gas flame, reducing its effectiveness. The melting phase required 3 hours! Much too long. (Problem #4.) (PPS. note added 23 Dec. I checked the dimensions of the crucible. It is a 30kg crucible!!! No wonder it was too big for the furnace! I had ordered and paid for a 14kg crucible. No wonder it was too big for the furnace. I should have checked before using it.)
The crucible has to sit on the furnace floor, reducing the heat exchange surface area, and narrow space on the sides restricting the flame volume.
Then it appeared that the flame was not as fierce as Stuart expected. The gas was piped from 2 cylinders, and one was not icing up as expected. It was close to full. Why was the gas not coming through? Could there be a ball valve somewhere in the system? Later we discovered that the pipe from that cylinder worked in only one direction because there was indeed a hidden one way valve. There was no direction arrow. (Problem #5.)
So, when we did get to the pour, and discovered the central core broken free (#1),
I inverted the now red hot cylinder to shake the core free. I calculated that the bore would fill with bronze and need drilling later. But would there be enough molten bronze to fill the cavity? I had allowed 1.5-2kg extra bronze to cope with unexpected contingencies but this would be cutting things fine.
So, we did the pour. There was a LOT of slag, possibly due to the slow melt. The molten bronze seemed to pour OK, and it filled the mold and the central bore. But it stopped about 3 cm from the top. Bummer!. Not enough bronze. Oh well. A learning experience.
I have washed and scraped off most of the investment. Oh Dear. A total failure. But, the threads were OK, so not a total failure. The worst area was the middle section which I had not painted with investment slurry prior to the the investment pour. I think that the PLA must not have been water tight, leading to the moth eaten appearance.
And worst of all….
It is only half the weight of the cannon, and it is just too bloody heavy!
I could fix the mistakes, reprint the part, and recast it.
But, you know what? I am not going to. The biggest issue is that even if I am able to fix all of the problems, and get a good result, it will be too heavy to move around. It will be too heavy to use even as a door stop. Hmm. Maybe I will clean up the failure and use it as a heavy door stop. Either that, or cut it up and reuse the bronze in the next casting projects, which will be much smaller!
This will be another failed, abandoned project to add to the list. (Chess pieces, etc). Oh well. Live and learn.
(it does cause me to appreciate the Ottoman cannon makers of 1465 who cast these parts with wood fires, where each component weighed over 8 tonnes!)
“The Artillerist”, Peter Webster is a Sydney based expert on historic Australian artillery. So I contacted Peter to see if he could explain how the 4 ton barrel of the Armstrong 80pr was elevated when it was mounted on the wooden carriage and slide.
Peter explained in detail that there was a screw sitting in a gunmetal nut which raised an iron bar on which the breech of the barrel rested. If more depression of the barrel was required, a wooden wedge (quoin) was inserted between the barrel and the iron bar. Peter had seen this arrangement on a cannon at Fort Queenscliff.
Several other readers have sent me diagrams from old publications of the setup, and I sincerely thank those readers for their help. Here is one of the diagrams.
Even though the barrel is different from my Armstrong 80pr, the dimensions of the platform match precisely. And the elevating screw and the quoin show as dotted lines fairly clearly.
I could have made the model screw and quoin from these details, but I decided to visit the Queenscliff Fort to see them for myself. Queenscliff is only a 30″ drive away. It has been Covid closed to visitors for almost 2 years, but had reopened very recently. So off I went today.
The fort was built in the second half of the 19th century to guard Port Phillip Bay heads from the French, the Russians, and even the Americans(!). At that time Victoria was wealthy from the gold rush, and the authorities were worried about a raid to steal gold which was stored in Melbourne banks and the Treasury. The land walls of the fort were surrounded by a deep dry moat. The large black powder guns faced the sea. The big guns were fired in anger only twice. First at the Pfalz, German steamer trying to escape Port Phillip Bay at the declaration of WW1. The “warning shot” almost hit the bow of the ship. Then there was a confrontation between the Australian pilot and the German captain. And the ship turned around, was commandeered, and was later used as a troop transport to take Australian soldiers to Gallipoli. The German crew were interned for the duration of the war. Astoundingly, the same gun was the first one to fire a shot in WW2, at least by Australians. But that was at an Australian ship which did not identify itself properly, so was a bit less glorious.
The 1.5 hr tour included the cells, the magazines, the remaining guns, the lighthouses, the museum.
Another interesting story which I had never previously heard, was from WW2, 1942. An aeroplane was launched from a Japanese submarine in Bass Strait. The plane flew around Port Phillip Bay, taking aerial reconnaisance photographs. It was spotted from Fort Queenscliff, but by the time it was realised to be the enemy, it had gone. Telephone calls to the Laverton airforce base were similarly unsuccessful in raising a response in time. The plane completed its mission and was picked up by the submarine. The pilot visited Australia after the war and related the story, and showed photographs. Needless to say, the Australian population was not informed until many years later. Google showed this article…https://www.ozatwar.com/japrecce/recce02.htm.
This lighthouse is still in use. Lighthouses are usually painted white, but this is one of only 3 black lighthouses in the world (?). Wonderfull stone masonry. Basalt.The unusual “disappearing” gun. An Armstrong 8″ RBL. Manually loaded, it could fire 3 rounds per minute!Similar mechanism, smaller gun.The museum had many interesting pictures and exhibits. This one is the gunners loading a 10″ rifled muzzle loader. Taken in 1880.Do you recognise the young lieutenant sitting right front? It is Australia’s most famous soldier. The son of German Jewish immigrants. He was the only soldier knighted by a British monarch on the battlefield, in 200 years. Later General Sir John Monash. He was in charge of the Queenscliff artillery in the 1890’s.A famous rifle. Lee Enfield.This had particular interest to me.
After the tour had finished I was quite disappointed not to have seen the gun and wooden carriage indicated by Peter Webster. So I asked the volunteer guide about it. She kindly introduced me to the gun expert at the museum. He took me to the only gun which matched the description, away from the tourist areas.
That’s me, next to the 80pr Armstrong rifled muzzle loader on a wooden carriage and slide.
Bummer! The elevating mechanism is missing, replaced by a wooden prop which was used when the gun was not in use.
Working with wood. It is quite nice to get back into the woodworking. And slightly daunting. Those saws can remove a finger or a limb in an instant of inattention. I use a 12″ radial arm saw, and an 18″ bandsaw. Somehow, the woodworking tools seem more dangerous than the mill or lathe. However, having seen videos and pictures of metal working lathe accidents, where an arm was ripped off at the shoulder, and similar, I know that they are ALL dangerous. At the time of writing I still have all of my bits.
At 1:10 scale, the wooden beams which form the base for the slides are 488mm long, and 30x30mm square section. They have a 5º slope back down to front.
I am using Victorian mountain ash, a pale, tight grained hardwood, and I happen to have some offcuts in my hoardings.
The wood is thicknessed to size, and the ends cut at 5º on the radial arm saw, which I bought about 45 years ago. Back then, B&D/DeWalt was considered a quality brand. I have previously decided which faces will be top and sides, depending on appearances.checking cuts for squareness at the correct angle.And today I used the CNC mill to cut out the carriage sides. 15mm mountain ash. The holes were drilled first, then brass pins hammered into the ash and the sacrificial base. Then the outside shape routed with a 6mm metalworking endmill. Some sharp internal corners will need to be filed or cut later.I use a high speed spindle to do the routing at ~10,000 rpm.
