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"
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…
So I annealed some thicker rod which was 2.5mm brass…
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…
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.
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.
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…..
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.
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.
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.
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.
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.
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.
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.)
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.
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.
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 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.
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.
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.
Oh. And some really useful woodworking tools which I bought from Banggood last year, and used for the first time on this project. They are laser cut spring steel, with holes and slots at 1mm and 0.25mm intervals, and a propelling pencil for marking. Accurate by woodworking standards, and they work really well, and were not overly expensive ($15-20 from memory).
And another bit of technology which I find useful with this project….
By fiddling with the magnification settings on our printer, I was able to print the plan on A3 paper, at a scale of 1:2 of my 1:10 model. The plan is quite accurate, allowing me to measure off dimensions of the components, angles and so on. This has been really useful.
Note that the wooden assembly is held together with large nutted bolts. And mortise/tenon joints as revealed by the Warrnambool LowMoor cannon. I will use bolts, and brass dowels, because MT joints are fiddly, difficult to make accurately, and will not be visible.
This is the video which I shot at the Flagstaff Hill Maritime Museum of the LowMoor 68pr cannon on an original teak wooden slide and carriage. It focusses on structural aspects, which I can review when I am building the model. It will probably be boring for most viewers, but I am posting it in case it is useful or interesting to some.
The cannon is actually located outside the front entrance of the museum. On this occasion I did not go through the museum, but can highly recommend it for many fascinating exhibits, including the Armstrong 80pr RML cannons, artefacts from the tragic wreck of the “Loch Ard” especially the beautiful ceramic peacock, and the recreated colonial village. It is well worth visiting.
When I sat down at the computer to draw up plans for the wooden chassis using the dimensions and photos I had obtained at Elsternwick, I realised that I needed some extra details. Some measurements I had just forgotten to take. And some details were not visible due to the protective covers on the Elsternwick cannons.
But, I remembered that there was a wooden chassis at the Maritime Museum, Warrnambool, and that it has not been restored. In fact it was an original teak slide and carriage, supporting an older smooth bore 68lb muzzle loader. I seemed to recall that the slides had rotted away to some extent, and that might reveal how the transverse beams were joined to the long slides, details that I had not been able to determine at Elsternwick. Being an older cannon, the slide and carriage might have been different from those at Elsternwick, but I decided to make the 2.5hr drive and check it out. 30 minutes further on were the restored wooden chasses at Port Fairy, so I decided to make a day of it.
So I was able to obtain the missing measurements, and to see that the transverse beams were joined to the long slide beams with large mortise and tenon joints.
However I was still puzzled by the barrel elevation mechanism. Was it a quoin (wooden wedge), or a screw mechanism? Or possibly both? And if both, why?
But, when I checked my blog at home that night, several readers from Australia and USA/Canada had provided references which described the mechanism. Thanks Jefenry, David and Richard. (and Australian expert, “the Artillerist” Peter Webster).
The barrel elevating mechanism is a large screw with the nut in the cross beam (the rear transom), which supports the hinged iron beam, and above that is a wooden wedge (quoin). Apparently the screw was for fine adjustments and the quoin for larger adjustments. I am reasonably convinced that was the arrangement of the Elsternwick 80pr Armstrong RML’s too.
In the diagram above note the roller/lever. That was used to lever up the rear of the carriage, to transfer the weight of the carriage and the barrel to the front wheels, permitting it to be rolled to the firing position at the front of the slide. Sometimes that process was bit uncontrolled, so the rope and bollard were added to control the rate of forward motion/descent.
Incidentally, that barrel is the one which was made in miniature by Jefenry, and featured on You Tube, firing at a range and off a canoe! Worth a search on You Tube. Just do a search on videos by Jefenry, or try these links.
The videos are from Jefenry, who is located in the USA.
So, today I battled 1.5 hours of post covid lockdown Melbourne traffic to take a closer look at the wooden slide and carriage of this 1866 Armstrong RML cannon which I am intending to model. There are 2 of them in the Hopetoun Gardens, Elsternwick. They are more complex than I had imagined.
The barrel is identical to the barrels which I had modelled on iron slides. The iron slides were a later improvement – modification.
It was a beautiful spring 20ºc day. I spent almost 3 hours photographing and measuring the wooden components. Some parts have been restored, and it was lucky that there are 2 examples to check and compare.
I was climbing over and under the cannon, and groundsman came over to check. Then a pair of grandparents came over with their 5 yo grand-daughter, and a further pleasant conversation followed.
Some examples of the photos…..
And an example of many pages of measurements and sketches…
There are 11 pages filled with details like this, representing my 3 hours.
And I still do not understand how the barrel elevation mechanism functioned. It could have been a wooden wedge called a quoin, but there appears to be a metallic disk set into the wooden bearer. Could there have been a screw mechanism which has since been removed/stolen/lost? Pictures on Google Images do not help. Does anyone know?
You might have seen the above photo in johnsmachines.com earlier this year. 2 Armstrong 80pr muzzle loading, rifled cannons are sitting on their ORIGINAL wooden slides, in Hopetoun Gardens, Elsternwick, Victoria. These were originally installed as garrison guns at Fort Gellibrand, Williamstown, Victoria and were never upgraded with the more modern, accurate iron and geared slides such as at Warrnambool, Port Fairy and Portland, and which were the inspiration for my 2020-21 modelling efforts.
I have decided that I will make another 1:10 scale model of the Armstrong 80pr RML, this time sitting on a wooden slide.
You might wonder why I am so obsessed with this particular cannon? Well, I wonder too. Perhaps it is the ready availability of an original in good condition, which I can visit, photograph and measure.
Anyway, I have made a start on this next model.
The next step was to centre the 10kg rod in a 4 jaw chuck, install a 3 jaw steady, and drill the 16mm bore. Sorry, no photos, forgot. I had made a long series 16 mm drill bit by turning a shoulder on the shank of a good 16mm bit, and boring an accurate hole in the end of some 5/8″ (15.875mm) drill rod, and silver soldering them together. Then honing the bore to an accurate 16mm diameter, along its 275mm length. It worked well. So well, that I can insert a 16mm “projectile” in the bore, and watch it slowly drop through.
Then, continuing to hold the blank rod with its 16mm bore in the 4 jaw, and using the tailstock to hold the other end I manually turned the exterior of the barrel.
My tandem trailer, was desperate for repairs and repainting. I bought the trailer about 23 years ago. It is 10′ x 5″, very solid construction, and a hydraulic tipper. I used it originally to transport animal manure to my olive trees. In recent years it gets more use on SWMBO’s building sites to remove builders rubbish.
Later, I increased the size of the ram to a multistage 5 ton unit, and changed the geometry to provide more lifting power. Also contracted a professional trailer maker to install Landcruiser hubs and wheels and heavier duty springs.
But the floor finally rusted through. So I installed a new 2mm thick steel floor over the top of the old rusted one. I should have removed the old rusted floor, but time was short, so I took the “lazy man’s” option.
Now, 23 years after the original trailer purchase, and about 18 years after the temporary floor fix, the floor needed to be replaced again. This time I did the job properly. I bought 2 sheets of checker-plate steel. Paid the supplier to fold the long edges. And started to remove both layers of the old floor.
Then attached the new floor to the trailer frame with galvanised hex head screws. You might wonder why I did not weld it in place? Well, removing the previous floor which had been welded in position was job which I never want to repeat. Plus, whether the new floor is galvanised or painted, welding destroys the zinc or paint, including in areas which cannot be touched up. The technique which I used allowed all surfaces to be thoroughly painted. So I removed the newly joined floor, and primed and top coated all surfaces, including the frame underneath.
Then re-attached the new painted floor permanently to the frame with the gal screws, and cut off the protruding points. I decided to not weld the floor to the frame, because that would destroy the rust inhibiting paint. I used silicone roof and spout sealant in the screw holes, and between the trailer sides and the new floor side lips. Then applied more silicone sealant into any cracks between the side lips and trailer sides.
Oh, I forgot. The cross members were U sections with the opening at the top. No wonder they rusted. Any accumulated water could not escape. A really dumb design decision by the maker. So I drilled drain holes in every cross member, removed the rust with a needle gun, and painted the insides of the U sections. I will finish the painting when the steel repairs have been completed.
Judging by the coats of existing paint, and alterations to the trailer construction, I reckon that this is the 4th major change to this trailer’s construction. It has done a lot of work. And lots more to come.
I have a 35 year old JCB back hoe, a left over from when I grew olive trees and made olive oil. These days it is used only as a yard crane, and other small jobs on a 5 acre property. But since I am between model engine and cannon projects I decided to expend some TLC on the rather neglected JCB.
One feature which always made me grimace was the broken slew lock plate.
A new plate is $AUD 1300 + GST I could not find a machine for wrecking, and was told that wrecked JCB 3CX’s are almost unknown, most owners, mostly farmers, keep them going for ever.
So I measured up the plate, drew it up on CAD, and had it laser cut from 20mm plate.
My JCB is a 1986 model, 35 years old. I have owned it for 10-12 years, using it for manure handling, as a yard crane, tree transplanting, and twice to lift a 50,000 litre water tank onto a tray truck. (in combination with a front end loader). Despite its age and hours of work (about 7200), it has been very reliable.
When I first bought it I engaged Enzed P/L to inspect and change any suspect hydraulic hoses, because many of them showed signs of cracking and delayering of the exteriors. And one had burst. I think that the onsite Enzed engineer remade and installed about 8-10 hoses.
Then recently, the hose to the rear bucket and boom controller burst. Well, actually it was the metal fitting which was crimped to the hose which split and allowed the hose to separate from the fitting, spilling quite a bit of hydraulic oil onto the ground. Enzed were on the job within a day, and an hour later the new large diameter hose and fittings were installed.
The hydraulic oil level was well down, and topped up with 20 litres.
I had been aware that one of the hydraulic cylinders had been leaking for many months, so not all of that 20 litre deficit was due to the burst hose. It had been leaking at the rate of one drop every 6 seconds for a long time, and increased to one drop per second recently.
I had recently purchased a kit of new seals for the leaking cylinder. After watching some YouTube videos, I decided to have a go at replacing the seals myself. No big deal really, except that I had not worked on a cylinder this large before.
The large gland nut was loosened before I removed the end pins. I had been warned that the nut would be extremely tight, and that it would be easier to loosen the nut while still attached to the JCB. The only spanner/wrench large enough was a Stillson wrench. I did not enjoy using it because it bit into the nut and marred the smooth surface. I had priced a new open ender spanner, but the cost was high so I used the Stillson. The Stillson was about a meter long, and the nut would not budge, despite using all of my strength and weight. Using a 1.5 meter pipe extension, the nut finally moved, and I loosened it until it stopped fighting. I caught much of the hydraulic oil which spilled out in a bucket, not to be reused of course.
I carried the ram into my workshop. At that moment I decided that any future resealing jobs on larger rams would be done professionally. It was quite heavy.
In the workshop I completed the removal of the large gland nut, discovered that the gland O ring and the main seal were in pieces.
Then removed the piston and its rod from the cylinder by pulling carefully.
The piston seals looked OK to my inexpert eye. But I had purchased a whole new kit of seals, including the piston seals and guides, so I replaced them all.
By the way, I had obtained a JCB service manual for my machine online, from Best Manuals, (USA) for $US19.99 and downloaded electronically. It had some very useful information. Including that replacement seals might be different from the originals. And they were. They looked different.
The seals went onto the piston fairly easily, with the assistance of a large cable tie, which was used to pull the large central rubber seal into its groove. The remainder of the piston seals were split, and positioned easily. The gland seals fitted easily, except for the large internal rubber seal which required considerable pushing and effort.
The gland was then pushed onto the piston rod, then the piston was screwed on, after cleaning the threads, treating them with Loctite 7471, and thread retainer 720. Then tightened with wrench and 1.5m extension.
Then I attempted to insert the piston into the cylinder. But it would not go. So I pushed harder. Still no go. Tried wiggling. twisting, pushing harder. No Go. Bummer. 4pm on a Friday afternoon. Long holiday weekend imminent. Threw the parts into the boot and drove to Enzed. About 15″ away. Maybe there is a special tool or press to push the parts together?
They helped me immediately. I guess that my previous business a few days earlier and quick payment of their bill helped. They mounted the cylinder in a chain- pipe vice, and pushed and strained, but no better result than I had. The piston with its new seals just would not fit into the cylinder.
So, he compared the old and the new seals. The new ones were 0.3mm thicker than the old ones. And the diameters seemed larger. I had bought the seals from a JCB dealer, who had said that they were “after market”. Originals no longer made for such an old machine.
Discussion. Decision. Use the old piston seals. The new gland seals seemed fine, so keep them. The old piston seals appeared to be in good condition, and they were installed. And guess what? The piston slid into the cylinder with some pushing. The gland nut was tightened. (with a Stillson I noted).
The charge for 30 minutes of heavy, dirty, specialist time??? $AUD 23.00. I said, “that seems too cheap”. “That’s OK” he said. They will continue to get my business.
Today I re-installed the ram on the JCB.
Fired up the diesel. No leaks!
Operated the bucket control……no leaks, but no movement! Bummer! What now.
Hmm. Could I have put the hoses on back to front? No. They looked correct.
But hang on, the cylinder is facing the wrong way! The paint scuff marks which were on the outside are now facing inside!
I HAD INSTALLED THE RAM 180º ROTATED!
So, left the ram as was, switched the hoses, and tried again.
WOO HOO! No Leaks! (including when I tried different ram positions off camera).
I am still waiting to pour bronze to make a 1:10 scale Ottoman bombard. I have all the equipment and materials ready to go. But, held up by 1. needing some dry, wind free days, 2. ability to have a friend on hand to assist with the pour. I need 2 successive days for making each mould and doing the pour. Waiting, waiting. Meanwhile, SWMBO has had me breaking up a concrete drive, manually loading the broken up concrete, and transporting it to the recycler. It took 3 x 2 ton loads, so far, and still more to go.
Then in lockdown, we decided to fix a leaking balcony at home, and replace some rotting, ceiling boards under the leaks. At 71, I dislike working on ladders, above my head. Almost finished, thank goodness. And no more broken bones.
The lockdown restrictions eased a bit last weekend, permitting me to visit my workshop. I have been waiting for some suitable weather to burn some rubbish, and it was not too windy a couple of days ago, so this was the first task…
I have been considering my next modelling project. Nothing really is grabbing my attention. But I had to use the JCB backhoe to load the concrete onto the tipping trailer and I was aware that the JCB is looking really tired. Not surprising, considering that it is 36 years old, and has 7200 hours on the clock. I bought it third hand, more than a decade ago, and used it for general farm jobs, including manure handling, transplanting mature olive trees, as a yard crane, moving machinery, digging trenches. As a general farm machine it was incredibly useful. When the farm was sold, it was just about the only big machine which I retained, because even on 5 acres it is still used occasionally.
So, until some new model engineering project takes control of my life, I will spend some time and TLC on the JCB.
I watch YouTube videos about megalithic sites around the world, including Peru, Cambodia, Russia, Bolivia, and especially, Egypt. I have been fascinated in the subject for over 50 years, since reading an article in National Geographic as a teenager, about the almost unbelievable stone work in Peru which was then ascribed to the Incas, (but that Inca origin theory now has many serious doubters).
One of those YT sites, “UnchartedX” , (to which I subscribe and support), frequently refers to the book “Lost Technologies of Ancient Egypt”, and recently did a 2 hour interview with the author, Christopher Dunn. The book was published in 2010, based on many visits to Egypt by the author. The interview led me to purchasing and reading the book. Although now 9 years (oops 11 years) since publication, his work is respected by Egyptologists, academics, and more free thinking enthusiasts such as YouTubers like Ben of UnchartedX, quite an accomplishment considering the degree of hostility between the opposing views.
Christopher Dunn is/was a toolmaker, engineer, and manager in the US aerospace industry, and expert user of CAD, CAM, lasers, metrology, and photogrammetry. He is also into ancient history. So when he visited Egypt he looked at the pyramids and other buildings and monuments, with the eyes of an engineer, and wondered how they “did it”. Over the course of many visits, he took increasingly sophisticated metrology devices and started to measure and take detailed photographs of monuments, temples, statues and quarries. He was staggered to discover the degree of precision to which many of these huge objects were made, in many cases of granite or basalt some of the hardest of all stones.
And he examined magnified views of the surfaces, to see the marks which remained, which might give clues about the tools which were used to create the objects, which in some cases are at least 4500 years old.
He carefully analyses the Egyptologists’ views that the tools were simple and primitive. Like copper chisels, and stone pounding rocks, and while not dismissing those views out of hand, leaves us with the impression that such results would be almost impossible in this CAD CAM era, and much less with copper tools and stone pounders. He does not mention aliens or pre-dynastic civilisations, but just states that the tools which made the pyramids, obelisks, huge precise statues, and stone boxes, those tools, unlike the copper chisels and stone pounders, have never been found.
He does point out evidence of large circular saws with a 38 feet diameter blade, hole saws up to 6″ diameter, and straight saws which have left tell tale marks in stone objects and quarries in many places.
In many cases, such as the huge, incredibly precise stone boxes in the Serapeum, and the absolutely identical pair of 40′ statues of Rameses 2, he just states “we have no idea how this was done”. The precision is not just in linear measurements, but in complex curves, and surface shapes and areas.
Dunn’s analysis is principally about the tools and engineering of Ancient Egypt. Equally fascinating, but not covered in this book, are the mathematics associated with the pyramids, but that is another story. Also, he does not believe that the Great Pyramid was designed as a tomb, but as a machine. But that also is the subject of another of his books, which I have not, as yet, read.
“Lost Technologies” is 360 pages, paper bound, illustrated with many black and white photos of variable quality, many excellent diagrams, and 16 pages of good colour plates.
The text is technical, but quite readable cover to cover. I found it difficult to put down. If you enjoyed Simon Winchester’s “Exactly” you will probably like this one.
This is not an in-depth examination of the question. It is rather my experience with a particular 3D printer. But I believe that my experience has been experienced by many other 3D printer owners, so I have decided to make this record.
The printer which I purchased was a Creality CR 10s. I bought it in January 2020. I had been considering such a purchase for a year or more, and finally took the plunge when faced by making components for the model Armstrong cannon which featured in this blog over the past 18 months, I realised that I would have to metal cast quite a few complex parts. And the “lost PLA” method seemed like the best option to cast those parts.
So I accumulated the equipment for printing the PLA, making the molds from jeweller’s investment medium, a potter’s oven for burning out the PLA and baking the moulds, a furnace for melting the aluminium and bronze, and assorted other necessary paraphernalia.
Choosing the 3D printer was difficult, coming from a knowledge base of close to zero. I asked members of my model engineering society which printers they chose, and why. I watched numerous YouTube videos, and read reviews. As usual, I discovered that the more information you absorb, the more confusing it all becomes. I have the same feelings when researching which car or camera to buy. Eventually, I decided to buy a lowish cost printer, with the idea that I would eventually replace it with a better unit for long term use.
For this first 3D printer I wanted a well known brand with a good reputation, a build volume which would allow me to print the biggest component of the model cannon (the barrel, which is 300mm long x 65mm x 100mm).
I was still mulling this choice when Amazon advertised a special deal for the CR10s, and I made a snap decision to take the plunge. Would I make the same choice today? Quite possibly (actually, no. see below). Although technology has advanced. I am now considering whether to add an Elegoo Saturn resin 3D printer to my ever growing list of machines.
So this is what I bought. It is an open frame 3D printer, with a separate box for the motherboard and controls, and a side mounted spool. Single extruder. Advertised as an auto self levelling base (but it is not. It is manual, time consuming and fiddly). Filament end detection (hence the “s” after the 10), which works well. The build volume is 300x300x400(h), which is at the high end of low cost 3D printers, and bigger than any of the low/medium cost resin printers. I used close to the full extents of the volume on several occasions.
Actually, the very first modification was the slicer software. The printer came with a free version of “Cura”, but I accepted some expert advice to use “Simplify 3D”, which I purchased ($AUD 175) and used exclusively until recently. More about that later.
The instructions for using the printer were in an illustrated 10 page booklet, and a pdf file. As instructions for assembling the printer, they were just OK (do manufacturers EVER test their instruction booklets on novices??). As instructions for fault diagnosis they are hopelessly inadequate. In my previous post I showed a paper back book which would have been immensely useful when I started this 3D printing journey, and HAS been immensely useful after almost 2 years of wallowing about in ignorance. (“3D Printing Failures” by Sean Aranda).
By trial and error (mostly error), I printed the parts for my model cannon, and also came to grips with the casting processes.
BUT. When I started printing components for my next project I experienced failures and frustrations which I could not overcome. The Ottoman bombard has only 2 components, the breech and the barrel, which I intend to cast in bronze, using the lost PLA technique. These will be the biggest castings, and biggest 3D prints which I have attempted. Not surprisingly, I had problems with the 3D prints. Some of my attempts at fixing the problems caused further problems. After reading Sean Aranda’s book, discovered that my problems had ALL been described, catalogued, and fixes known.
The problems were:
1. Poor plate adhesion causing models to break free during printing.
2. Poor adhesion between layers causing gaps and structural failures.
3. XY shifting between layers
3. Gaps between filaments which would cause casting holes.
4. Excessive stringing.
5. Lumps on surfaces.
And this was typical of the failures….
Then I decided on some upgrades….
An enclosure to prevents drafts, and keep the printing environment warm during cold nights. $AUD155. A temperature and humidity logger kept a record of overnight temperatures. The heated printer bed provided the heat. I noted that temperatures remained between 22 and 26ºc inside the enclosure.
An all-metal fully geared extruder. $AUD25
A filament dehydrator, and warmer. “Sunlu” brand. $AUD60. Old filament can be reconditioned by warming at 50ºc for 4-8 hours. The same machine can hold the filament during printing to keep it warm and dry.
Around this time I experienced a serious filament leak and blockage which bent the hot end enclosure, broke the wire to the thermostat, and broke some insulating material. The leak was caused by a loose extruder nozzle, and an imperfectly seated Bowden tube. It was probably repairable, but when I saw that the cost of a replacement unit, including the wiring loom, hot end, 2 fans, silicon boot, etc was only $AUD35. So I bought one, had it installed easily in a few minutes. It came very well packaged, and quickly.
Also about this time I read Sean Aranda’s book. It has been a game changer.
Aranda uses “Cura”, and although his fixes can been used by any other slicer, one of my problems was holes between walls and internal surfaces. He says that this is a problem which is worse with “Simplify 3D” than with “Cura”, and he also thinks that “Cura is a better program overall, mainly due to the quality and number of online updates. The fact that “Cura” is free is an added bonus.
4. Sean Aranda’s book. “3D Printing Failures”
5. Changed slicer to “Cura”. Although it is called “Ultimater Cura” it works on most if not all 3D filament printers.
6. Changed the stick-on printing surface to a new 3M cover. This was after I read the product information which stated that these surfaces last for only 10 prints! I am quite sure that mine lasted for at least 50 prints before becoming unusable. Now I print on different areas of the surface, and keep a record of the number of prints at each location. Since then I have bought a magnetic cover which I will use when the current 3M cover starts to fail. (p.s. I have now installed the magnetic base, and so far, it has been wonderful!). No break aways despite not using brims or platforms, and easy to remove prints
After all of those changes my prints have been excellent. No break aways, no X-Y layer shifts, good adhesion between layers, better surfaces, and no holes/gaps between filaments. The only problem is that I am not sure exactly which changes were effective and which ones were not. Probably they have all helped to a degree.
Postscript. I have been considering buying an Elegoo Saturn resin printer, or maybe even substituting the Saturn for my Creality CR-10s. From the reviews the Saturn produces much smoother surfaces, and more precise dimensions. And the prints are much faster. My 3 and 4 day barrel prints could be printed 5-10 times faster. The known down side is the is the cost of the machine (on special at Amazon at present for $AUD639), the smell, the need to avoid skin contact with the uncured resin, the desirability of a print washer/UV curer, and the need for extra space. The other major consideration for me is the smaller maximum print size. 200x192x125mm. The bombard parts would need to printed in halves and glued together in order to make the molds. So, while the CR 10s is working well, I will hold off buying the resin printer. There is some advantage in waiting because 3D printing is a constantly evolving and improving technology.
So, were the upgraded components worth it? A resounding yes, as far as I am concerned. Still pondering the Elegoo Saturn
P.S. a month or 2 later. Since I wrote the original article I have taken delivery of, and installed some 1 meter cable extensions, which were made for this machine. Obviously I am not the only Cr10s owner to have decided that the cables are a bit too short. The 6 or 7 cables were fitted with connectors and installed quickly and easily. The printer functions perfectly, and I can now place the control box a comfortable distance from the printer enclosure without worrying whether the too short cables will cause a print failure. Actually, the one meter extensions are a bit too long, and need to be carefully positioned to avoid snagging. Half a meter extensions would have been ideal. And the cost? $AUD35 with free postage. Considering the labour involved in making and packaging these items, the price was cheap.
I guess that title should read “2 Person Tongs” but I doubt that SWMBO will be volunteering.
I am still planning to pour a model bronze Ottoman bombard.
The plastic model has been 3D printed, the flasks for the investment powder mould are ready, and I have the potter’s oven ready to dry, burnout, bake, and heat the moulds.
I have borrowed a melting furnace from Stuart Tankard, which is large enough to fit the crucible. The crucible has 14kg capacity. The crucible itself weighs 4kg. Unloading the furnace from my Toyota Landcruiser cost me a couple of broken ribs, which set back the project a few weeks.
Then I wondered about tongs to insert the crucible into the furnace, and, more importantly, how to lift the crucible full of molten bronze out of the furnace and pour the bronze into the moulds. The weight to lift and pour I estimate to be: bronze 10kg, crucible 4kg, plus tongs say 4kg = 18kg. The crucible with its bronze load will be at approx. 1100ºc / 2000ºf so some distance will be required for the gloved hands from the red-hot load.
I have several pairs of tongs for smaller crucibles, but nothing approaching a 14kg crucible. So I asked Stuart T for his thoughts on the matter. He recalled seeing a video by an MSMEE member and suggested that I check it out.
John M’s tongs looked like they had been designed by an engineer, which was actually the case. I contacted him (by email because Melbourne is in Covid lockdown), and he generously offered to send photos, a video and a drawing.
I copied his design, with a few modifications based on the materials which I had on hand, and also to enable a 2 man lift and pour. In retrospect, I could have fabricated a one man pouring apparatus, using a swivel on a frame, but to be honest I would prefer someone else present for safety reasons.
The remainder of the tongs construction was basic cutting, welding, and drilling.
I used to be a half reasonable amateur welder, but lack of ongoing practice lately, and dodgy eyesight is my excuse for the lumpy welds and essential use of an angle grinder.
Next steps…. I need some dry, non windy weather, and availability of assistance for the pour. I will make the first mould, of the breech since it is shorter than the barrel, dry it, burn out the PLA, and bake it at 750ºc. That will take most of a day. While the baking is in progress (about 4 hours), I will start the melting of the bronze ingot. Stuart says that I will require 2 full 20kg cylinders of propane.
Then the pour. Then after some cooling with fingers crossed. Camera running…..
The 6th Victorian Covid lockdown was the shortest, but seemed to hit me the hardest. It was unexpectedly relaxed after only 5 days in regional Victoria, where I live. With escalating numbers in Melbourne, and Sydney, and NSW reacting by putting its collective heads in the sand we expected the be in lockdown for weeks or months, and frankly it was quite depressing. For the first 3-4 days I did a bit of garden tidying (with a chainsaw, much to SWMBO’s horror), and time on YouTube, Ebay, Banggood and Amazon. A fair bit of impulse buying, as follows.
Paragraph deleted. My political and religious views have predictably caused offense to some of my readers. While I do not resile from any of those views I accept that others have different views, and me having a rant is unlikely to be at all persuasive. So I have removed the paragraph. For those who agree with my views, my apology. Any further conversation about Trump, Liberal and labor politics in Oz, and religion, will have to be in private. (I still consider Trump to be a lying, ignorant, con man, and a disaster for USA and western democracies.)
So, having offended and lost 3/4 of my readers I will get back to my little buying spree…..
Firstly, a book.
I read some good reviews about this book, and since I have had considerable frustration with my 3D printing of late, I decided to buy it. 3D PRINTING FAILURES by SEAN ARANDA.
Paper back, 298 pages, large format, large print font size, 2020 edition. Under $AUD30 including postage from Amazon.Australia.
And it looks excellent. Clearly laid out and written, lots of pictures and diagrams, and the author even gives his email address and offers expert help if there should be a problem not covered in the book.
Some of the pictures admittedly are not great quality, but the author has a service which astounded me. If proof of purchase is emailed to him he will send high definition colour photographs for download. He sent me all of the photographs within 24 hours of my request. AND, a pdf version of the entire book. AND, a promise to send me free of charge a PDF version of the 2022 edition which will be published near the end of this year!
I have cherry picked some of the chapters and I am VERY impressed. They are VERY helpful. Some random pages follow….
This book should be included with every 3D filament printer purchased. Note that it does not cover liquid 3D printers.
In my previous post I showed a photograph of the enclosure which I cobbled together from cartons and a blanket to try and avoid printing problems arising from overnight temperature drops, and draughts. I intended to make an enclosure from MDF and perspex, but while browsing Ebay came across this one.
As you can see it was not a trivial cost. But when I factored in the difficulty in obtaining the materials during the lockdown, and the fact that the commercial one claimed some fire resistance, I bought it.
It came today, and with some levering of the cover on the frame, it assembled quite neatly, tightly, and well. Here it is with my printer.
As you can see the electronic control box is outside the enclosure. There is a flap on top for those who prefer the filament reel on top.
The front and top zip open. And there is some spare room for bits and pieces. It does look slightly neater than the previously used cardboard boxes. The printer is fully enclosed, even with a build in floor. The price seems to have risen a bit since I paid for this one. Time will tell if the print quality improves. I am predicting that the print quality will improve. After reading the chapter on fire safety and 3D printing in the book above I will feel more comfortable about leaving the printer unattended with this “Fire proof” enclosure. I suggest interpret that as “fire resistant”. I will be watching temperatures closely for the first few runs.
Still on the subject of retail therapy, a couple more purchases….
This is a woodworker’s gauge from Banggood. I bought it after watching a YouTube video about its uses. Nicely made, and reasonably accurate by wood working standards. I will do a separate post about it when I have more fully explored its applications. (it is for making perfect grooves and lap joints on a table saw).
And finally, this one was a splurge, impulse buy. But something that I had wished I had on quite a few occasions when making models.
As you can see it is a pin gauge set. It is Imperial because it was a fraction of the cost of a metric set. 190 pieces of ground and laser labelled cylinders, up to 1/4″. They seem to be as accurate as my Mitutoyo micrometer can assess. It does mean that I will be committed to a moment of calculation to metric when in use. Cost? About 50 cents per piece, including the case and postage.
Fortunately for my credit card, the lockdown ended 2 days ago. I have spent a couple of short sessions in the workshop, tidying up and doing some machine repairs and maintenance. Nothing really to show. But it is nice to be back.
It has been cold here during the current lockdown. And I mean temperatures. Not by American midwest standards by any means, but since we are confined to our homes except for limited predefined purposes, some days and nights are chilly. Down to 5-8ºc here.
I have been spending a lot of lockdown time doing 3D prints. And really struggling to get decent results.
Some of my GSMEE colleagues have been urging me to make an enclosure for my 3D printer. To be honest, Stuart T had urged me originally to buy a printer with an enclosure, but I pressed ahead and purchased an open structure model because I wanted the extra print size it offered. The Creality CR10s can print up to 300x300x400mm which I have fully used for my Ottoman bombard prints.
But in recent weeks, with the onset of the cold weather, I have noticed a distinct deterioration in print quality, particularly with poor layer adhesion when printing overnight, when the house heating is turned down or off.
So I decided to make an enclosure!
But, I did not have the materials on hand, and visiting hardware stores is verbotten with lockdown rules.
So, don’t laugh. This is what I cobbled together……
A couple of cardboard cartons, an artist’s A0 paper case (SWMBO hasn’t noticed it missing yet), and a blanket.
The heated printer bed is the heat source, at 50ºc. And I was surprised at the temperatures reached inside the rickety construction.
The steep temperature rise on the left is inside the enclosure after printing started. As you can see, the temperature rose from about 18ºc (room temp), fairly quickly to over 30ºc. After midnight, when the house heating was turned off there was a slow drop to 25ºc, and then a further drop to 18ºc when the printing finished and the bed self turned off.
The temperatures were measured with this gadget. A temperature/humidity logger.
And the printing result??
This is the best quality print which I have had since the onset of winter weather. It is solid, water tight, and a reasonable finish. 0.2mm layer height. It is a molten metal pouring funnel, so I was not trying to get a super smooth finish, just an intact water tight object.
As soon as I can get access to Bunnings, I will make a more purposeful enclosure. Meanwhile, the cartons and blankets can remain in use.
I have given some thought to how to manage the bronze pour for the barrel of the Ottoman bombard. It will be at the size limit of my potter’s oven for the PLA burnout.
The red 3D printed PLA is the barrel. The breech, although significantly shorter, weighs almost exactly the same, but being shorter, should be less problematic. The wall thickness of the breech is greater than the barrel.
I had thought that the steel cylinder would be adequately long to cast the barrel, but it is about 50mm too short when I take into account the bronze feeder reservoir which will be required. So I will add a 50mm length, probably by arc welding another bit of tube to one end. It wont matter if it is not a perfect join. I will make it waterproof with duct tape. The tape will burn off during the investment melting/burnout.
I will cast the barrel with the threaded end downmost. The molten bronze feeder reservoir will be 60mm deep which I hope will provide adequate pressure and extra molten bronze if required during cooling contraction.
I decided that the usual rubber pouring funnel (pictured above at the bottom of the steel cylinder) would not have an adequately large bronze opening or reservoir depth, so have 3D printed one in PLA. The PLA will disappear during burnout, but will leave its shape in the investment medium and become the funnel and reservoir.
Hard to get your head around that one? It certainly was for me when designing it.
You (and I) need to remember that any space around the PLA will become investment medium. The PLA will disappear and become a void which will be filled with bronze.
The 3D print took over 8 hours. 0.2mm layers, 210ºc extruder temperature, 3000mm/min. I will need to do a similar 3D print for the breech. If either or both pours fail the whole process will need to be repeated.
Still in lockdown. Cannot visit my workshop due to the 5km travel limit. So 3D designing and printing at home is fairly good use of my time.
I have been attempting to print a 1:10 scale barrel of the Ottoman bombard, in PLA, so I can make a cast in jeweller’s investment, and use that to pour a bronze version of the cannon.
I borrowed a big furnace to melt the bronze, and broke 2 ribs unloading it from my vehicle. That was about a month ago. They still ache a bit, but apart from careful positioning in bed, are steadily mending. I have to sleep on my back, which would normally make my snoring unbearable, but the CPAP machine is working quite well. SWMBO absolutely insists that it is in constant use.
And I have purchased a length of 5″ stainless steel pipe to make the mold.
I have featured the Ottoman bombard in previous posts, having made a wooden version some years ago. It is over 500mm long, and 107mm diameter. In 2 pieces with a big thread joining the pieces.
I can’t really justify a bronze version. It will weigh close to 20kg. But it is a challenge. And I think that it will look more authentic in unpainted bronze.
I printed the breech part a few months ago.
3D PRINTING THE BARREL.
The barrel is 315mm long. My printer has a maximum print size of 300x300x400 mm so I was not anticipating any problems. I knew from the slicer program that it would take 2/3 of a 1kg reel of PLA, so I bought some new transparent PLA, thinking that it might melt/vapourise more completely in the burn out cycle of the production than the coloured PLA.
So I tried to print it. I have lost count of the number of unsuccessful attempts. Each time the print would start well, but at some point, sometimes after a whole day or 2 of printing, the print would come loose from the printer base and I would have clean up the mess of PLA spaghetti, and start again. I cleaned the printer base thoroughly. Scraped it. Wiped with acetone. Re-levelled it multiple times. But every time the print would break free.
I also noticed that I was getting a lot of stringing, and lumps of PLA would form on the printed surface, cool and harden, and sometimes the print nozzle would hit the hard lumps. That is when the print would loosen from the base and eventually break free.
I have been using a 3M printing cover over the aluminium printer base, quite successfully for over a year. Maybe the cover had worn out. I looked up the P.I. for the cover, and yes, it has a stated expected life of 10 uses! So that was likely the cause of the adherence problem because I must have used that cover at least 50 times!
I had no replacement 3M cover, so I reverted to the original cover supplied with the machine, which was boro-silicate glass. Initially it worked well, with good print adherence, but the hard lumps were still forming, and when the nozzle hit them, there was enough force to break the glass plate free.
What could be causing the hard lumps?
I watched multiple YouTube videos. Re-levelled the bed again. Checked every nut and bolt on the printer for tightness with no problem found. Checked the Z axis for level.
By this stage I was contemplating buying a new printer. Maybe one of those liquid + UV light jobs. But one of those big enough to make my barrel would cost thousands. So I got a quote from a professional printing service to print the barrel…. almost $AUD600. I would have done that, but the print is destroyed in the making of the cast, and it is possible that more than one attempt of bronze casting will be required. I was considering abandoning the entire project.
One last try at a print. I replaced the 3M cover with a new cover, and started a new print with a new reel of red PLA.
All seemed to be going well.
The print was adhering solidly to the new 3m cover. The hard lumps were still appearing, but the print head ploughed through them or knocked them off completely. The problem was, that after 3 days of printing, with 10% of the barrel still to go, the multiple jarrings were producing axis shifts. The appearance was pretty bad, but I figured that I could fix it with some extensive post printing hand finishing.
By this stage the print was almost 300mm high, and I could watch the laying of the PLA extrusion from the print head directly. In retrospect I should have used a mirror to do this at a much earlier stage.
What I saw explained the issue of the hard lumps appearing.
PLA was slowly oozing from around the base of the extruder nozzle. It was gradually building up into a pea size lump, and eventually falling off onto the print face!
So, I paused the print, picked off the accumulating lump, and watched some more. The same thing happened.
Why was the base of the nozzle leaking? Another pause. Checked the tightness of the nozzle. It was totally loose. About a full turn!
Tightened it up. Resumed printing.
The next layer did not adhere at all to the previous one, because tightening the nozzle had lifted it at least one mm.
I thought that I could start a new print of the final 10% of the barrel, and glue it to the part pictured, but when I examined it, the layers were poorly adherent, and falling apart. It went into the plastics bin. I expect that the loose nozzle caused multiple print faults in x, y, and z axes.
So, I am now 32 hours into the next attempt, with 47% completed.
Now that the Model Armstrong cannon is finished, I feel able to move onto some smaller projects which have been hanging around on my to-do list.
4-5 months ago I had these parts laser cut from 3mm and 4mm plate. GSMEE members have been making the Kant Twist clamps, and over the past 3 workshop sessions I have made a pair of the larger clamps.
The machining of pins and jaws was very basic so I did not record those processes. The laser cuts holes were accurate enough to be reamed to size. I found 2 annoying mistakes, neither of which was fatal. There is an extra hole in the small side arm. And the position of the pivot hole in one of the arms is about 1mm out. Not sure how that mistake crept in. Neither of these mistakes will affect the functionality of the clamps.
I would suggest one design change to the clamps, which I will apply to the small ones when I make them. I would add a small extension to the handle boss, say about 12mm, and knurl it. That would facilitate speedy changes to opening settings, before tightening with the handles.
Time and use will tell whether my choice of brass was sensible.
I know that these clamps can be purchased on Amazon and other sites, but this was a very satisfying project, and I have no regrets about deciding to invest the time to make them.
Small drill bits (up to 3.2mm diameter) are almost impossible to sharpen. Most of us just just buy new ones when our bits get dull. They are not expensive even in packs of 10.
But, sometimes we have parts which require sharp bits. (see recent post on installing model cannon sights). Even new bits are not necessarily correctly sharpened. I use Sutton drill bits which in small sizes cost ~$AUD18-20 for packs of 10 bits, but for crucial jobs I would like to touch up even those quality bits. The Sutton bits which I used for the cannon sights worked well, but the tense job made me very aware that in future I NEED to make sure that the bits are sharp.
So, I made a jig for sharpening small drill bits. The plans were published in Model Engineer 29 Dec 2000 and 26 Jan 2001.
It was a simple build. Took me 2 workshop sessions of about 2 hours each. I had the jig plate laser cut, very inexpensively from 2mm mild steel plate. Distributed to interested GSMEE members. The drill bit holder is an Asian copy of the English “Eclipse” pin chuck original. Also inexpensive. Came with 3 collets, to hold sizes up to 3.2 mm diameter. Cost $AUD10 inc postage. Note that the 1/4″ shaft actually measures 6.25mm diameter.
I used M2 and M3 metric fasteners in preference to the specified BA10 and BA8 fasteners.
The pin chuck should be through drilled in order to accomodate longer drill bits. The Asian pin chuck was not difficult to drill with a 3.5mm cobalt bit. It appeared to be case hardened only. And I used 2mm mild steel plate instead of the specified 16g brass plate for the jig. The wheel mounts were modified to cope with the different plate thickness.
The plans and instructions for use are in the articles in Model Engineer listed above.
p.s. GSMEE members who intend to use the laser cut plates. The drilling positions marked by the full thickness crosses can be successfully drilled to 1.6mm and 2.5mm by using sharp drill bits at high speeds- 3000rpm, slow feed rates, and cutting liquid. I used TapMagic.
And, it works! Here I am testing a 1.5mm bit which has been sharpened with the jig. Drilling through 4mm mild steel.
The sights were the final parts to be made for the model Armstrong RML.
There were reasons for delaying these items. They are tiny, easily dropped and lost, have tiny almost invisible details (to my eyes), and involve fine and very deep drilling into the barrel, on which many hours have previously been expended.
First I looked up every reference I could find about the full size originals. I could find no picture of the sights on the 80pr Armstrong, but I did find some diagrams of the sights on the Armstrong 64pr, on which the 80pr was based. Another problem was that there were rapid developments in sight technology, and I had to decide which period I would choose. The later periods (after 1880) had complexities which did not exist in 1860. In the end I just made decisions, knowing that they might not be exactly correct, but thinking that if further information surfaces I could make and install new sights.
The next step was to drill some 2mm and 3mm holes into the barrel.
First I milled 3mm flats. The first milling bit, solid carbide, just snapped as it bit into the barrel from the side. A HSS bit was more long lived.
Next, a 2mm hole was drilled right through the barrel, missing the bore, and exiting through the bronze bracket which supports the elevation quadrant gear. At 40mm deep that hole qualifies as deep drilling. Tension drilling.
Most hobby modellers who use a CNC lathe, run the lathe with Mach3 software. Some have progressed to Mach4, but apparently 4 is not straight forward, and my expert advisor says that it is best to stick with Mach3 for the time being.
Mach3/4 requires instructions to control movements of the lathe carriage (X and Z movements), spindle on and off, spindle speed, coolant on and off etc, and those instructions are in the form of G codes.
G coding is not difficult to learn. There are excellent YouTube tutorial videos on the subject, Udemy courses, books, and so on.
The problem is that mistakes in G coding can be easily made, costly, and sometimes scary. The biggest problem is that G coding is time consuming.
Fortunately, software is available to make G coding automatic, fast, and reliable. This post is about the program which I use for G coding. It is called Ezilathe. It is available at no cost as a download from CNCZone. (see details of downloading later in this post).
Ezilathe was written by Stuart Tankard, who I met a decade or so ago at a meeting of GSMEE. Stuart gradually persuaded me to get into CNC, and frankly, the decision to do so has resulted in a quantum leap in the scope and standards of my model engineering efforts. Now I use a CNC lathe, CNC mill, CNC rotary table, CNC 3D printing.
But I digress. This post is about G coding for CNC lathe. Until Ezilathe came along, I was programming G codes manually, making mistakes, and consuming lots of time. And experiencing crashes. Exciting, damaging, and sometimes dangerous.
To CNC turn an object, the profile must first be drawn with a CAD program such as AutoCAD. There is a very basic CAD drawing facility in Ezilathe, but it is so basic that I prefer AutoCAD. In AutoCAD I then rotate and move the object as it would be held in the lathe chuck, and move the tailstock end of the profile to the X=0, Y=0 position. Only half of the original drawing is required, so I delete everything below the X 0 line. I delete or hide all lines which are not part of the profile. The profile can be saved as a polyline, or as separate lines, arcs, splines etc. It is named and saved as a dxf file.
Then Ezilathe is opened, and the dxf file is imported.
The stock diameter is entered. The z position of the tailstock end of the profile is entered (usually Z=0). Feeds and speeds are entered using the tables in Ezilathe or another source. I use an app named “FS Pro”. Also select which lathe tool is to be used (the lathe tools are all entered in advance) or select a “point tool” which has an infinitely sharp point, and no width. In the example shown in the pictures below the turning was achieved with one tool. If multiple tools are required on one job, each tool will have to been set in the tool editor. So far I have not used the tool editor, but I can vouch that it works well, having seen the superb results which have been achieved by Stuart.(see the photos below)
Then the polyline of the profile, OR, each line and arc etc is selected in the machining sequence. Important not to miss any small lines or arcs as unintended results can occur. That is why it is sensible to save the original drawing as a single polyline. (Stuart tells me that any gaps will be automatically filled by Ezilathe as straight lines.)
Then go to the simulator, and see how Ezilathe will manage the sequence of cuts. In the picture below, the cuts are the straight lines, and there are 2 finishing cuts along the profile.
If all looks well, generate the G code. I usually visually scan the G code, looking for obvious errors. Usually there are no errors. Save the G code. Then ready to use the G code to make the part.
AN air cut with no work stock or cutting tool is sensible for beginners.
There is a lot more to Ezilathe. This has been a very brief introductory summary. Creating a lathe tool library, and entering startup strings for different lathe setups for example.
To download Ezilathe, you need to register at CNCZone. It is quite a good, useful site. In CNCZone go to downloads, Postfiles, Page 2. Select Ezilathe, and Ezilathe.pdf. The pdf is a comprehensive manual. Save them to a directory named C:\Ezilathe and unzip them. The program has been fine tuned, and updated. The latest version is 1.7.3. Then, on page 1 of Postfiles there is a small bug fix, Version 184.108.40.206. 220.127.116.11 is an executable which should be run after 1.7.3 is installed. If there are problems or questions Stuart can be contacted via CNCZone.
I have no hesitation in recommending this excellent program. It is just amazing that it is free.
Well, that heading is bit misleading. I had no pre-existing plans. I drew plans up myself, using the original cannon to measure, scale down and get my model dimensions.
In my posts over the past 18 months you have seen plenty of pictures of the original cannons, and the models.
I decided to model the particular cannon because I liked the shape, the degree of mechanical complexity with gear trains, riveting, etc, and because of the association of the town (Port Fairy) with my son in law. Also, because Port Fairy is within driving distance, if further dimensions and details should be required, which they were.
I thought that a model would look interesting and impressive. And it could be built in 3 distinct stages. Chassis-slide, carriage, and barrel.
So, in the order in which things happened……. (this info is all in older posts, so turn off now if the repetition is boring. I am writing this post for an overseas reader who wants to know how it was all done.)
I used a digital camera and iPhone to take photos of the entire cannon and its components. Close up, and from a distance showing the relations. The straight lateral, front and rear photos were particularly useful. In total, about 200 pictures. The photos were printed A4, and catalogued. As the model building progressed I realised that I had missed some components, and 2 further photo sessions were required. That was complicated by the Covid restrictions, but managed with some delay. The best photos were in overcast weather conditions, with and without flash.
I measured as many dimensions as possible, using a builder’s tape measure. The dimensions were recorded on hand drawn sketches in a note book, and a phone app (<My Measures Pro>. Very useful). On a later trip I used digital callipers for some small details. The barrel was measured using circumferences, and calculating diameters from those.
Using AutoCAD, I drew up a simple side profile plan. In that process I realised that many more measurements were required, and repeat visits were made. Actual components were later modelled using 3D CAD and saving as STL files. The STL’s were used to make 3d prints for casting, and in some cases just to see how the part would fit into the cannon assembly.
I searched the Internet for any references to the particular cannon. In that process I discovered that the particular cannon was unusual, and it appeared that all 26 examples from the Royal Gun Factory had been sent to colonial Victoria. Identical cannons were to be found in 2 other towns close to Port Fairy, and in 2-3 locations elsewhere in the state of Victoria. The design (of the 80pr original) was very close to a smaller capacity cannon (64pr) of which examples are still located in Hong Kong, Singapore, UK and probably elsewhere. It gradually dawned on me that the differences between the 64pr and 80pr related only to the construction method of the barrel, and not its appearance. Google, Google Images, Wikipedia all had information. I even discovered some images of simple plans with dimensions of the 64pr cannon, which corresponded very closely to the dimensions which I had obtained from the Port Fairy original.
As I posted progress of the model build on this blog, various readers offered further information, some of which was very useful. I have had some very satisfying subsequent correspondence with model cannon builders. In fact, the blog correspondence has led to some very useful experts who have been of immense help. One even supplied me with a copy of the original operating instructions for the Warrnambool 80pr cannons.
Searching for books on the subject of artillery in the 19th century has produced two which were published in 1877 and 1897. These are available free of charge as downloads, and bound reprints were purchased in addition. The cost of the bound books was very reasonable ($AUD20, and $AUD50). These have been thoroughly read, thumbed, dog eared, and used. So much so, that one of them is due for replacement.
Discussion with several experts has provided further great information, and resolved some of my questions. I had been mislead by some inaccurate restorations of the cannons at Warrnambool and Portland, and my suspicions about the restored details were confirmed in those discussions. The cannons at Port Fairy have had no restoration, which has resulted in severe rusting, but at least the remains are original and genuine.
Steps 1,2 and 3 occupied me on and off for about 5 days. 4,5,6 and 7 occurred progressively over the following 12-18 months during the model construction.
Regarding the accuracy of my scale models compared with the originals, I make the following observations.
As far as possible the linear dimensions are at a scale of 1:10. That was the scale of the first cannon I modelled, and I have stuck with that 1:10 for consistency, comparison between different cannon models, and simplicity of conversion. Of course that means that surface areas are 1:100, and volumes and weights are 1:1000. I have made some compromises to enable use of standard fasteners, shafts, and bevel gears, but have kept the compromises as small as possible consistent with the visual appearance.
Materials. The original cannon was constructed of wrought iron, cast iron, bronze/brass and wood. Steel was used only for the top surface of the slide. I used mild steel for the slide, the chassis, the carriage and the barrel. I used bronze or brass where the original had bronze. The wheel assemblies were cast iron on the original. I was restricted to cast aluminium and later cast bronze, but since these components were painted, the exact metal is not detectable, and probably irrelevant. The original wooden chassis/slide was made in the UK. The later iron chassis/slide was ,made in the UK but modified in Melbourne. That is the slide which I modelled. I imagine the original wood components to have been oak, but with no certainty. Scaling wood is difficult, due to the problems of scaling the figuring. I have some European oak offcuts, but decided to use Australian jarrah, because of its fine grain and attractive reddish colour.
Colours. I could find no reference anywhere regarding original colours. The experts had no hard information about colours and neither of the books mentioned colours. Some opinions were that black was most likely, and for cooler climates that seems reasonable. But in a hot Australian summer, black iron objects can be too hot to touch. I therefore suspect that white or at least a lighter colour would have been most likely used. But, you know what? SWMBO offered the most sensible advice. She said that if the model is to be on display it has to look attractive. She recommended painting the boring bits flat black (carriage sides, recoil tube, wheel assemblies), and leave the remaining metal uncoloured. Even the copper rivets, which would have been iron in the original. And to polish the bronze and brass components. So that is what I have done.
The base. A lot of thought went into this. The original ran on circular iron tracks which were set into concrete slabs. I rejected a circular track on the grounds that the model would have been too wide for convenient storage and display. I also rejected concrete or model concrete in favour of the eventual choice. That decision, (incidentally, not “set in concrete”…. might be changed at a later stage), was for a single piece of 12mm thick gloss black cast acrylic Lexan, sandwiched to a piece of thick plywood which is painted flat black. It looks good IMO, is hard wearing, and reflects the internal components so they can be seen. The first model Armstrong which I made was set on a wooden base with oil polished top and black painted sides. That also looks quite good. (IMO).
I might add to this list if further memories surface of the various processes used in the planning stages.
Just one picture for those readers who never read the text….
I made them promise to not make me laugh or cough or do any heavy lifting. And it was a pleasure to attend another face to face GSMEE meeting after a few weeks of Zooming.
And Swen Pettig brought along his Grasshopper beam engine for a progress assessment.
Swen has also recently made this sphere making lathe attachment. The cutter is a 6mm diameter TC disk. He showed us an example of a job, which has a lovely finish and excellent shape, but a rather thick neck. Swen plans to make another cutting tool with a sharper point to make thinner necks on the spheres. Chatter has not been a problem with this tool.
I am not quite ready to show the Armstrong RML gun, because it is still waiting for me to get back into the workshop for some finishing touches, so I brought some goodies to show which I recently bought from Banggood.
And this one is a woodworking tool, which I have wanted for some time, but the US version is about x4 the cost , and postage is an extra deal killer. The costs mentioned all included postage.
Today I picked up the laser cut metal plate which will become the small drill sharpening jig. For drills bits up to 3mm. You might ask why bother? Well, I can see the jig being used where I want a really sharp tiny drill, on a critical job. I would touch up the cutting edges on even a new bit.
The drill bits to be resharpened will be held in a small collet chuck, purchased commercially for about $10, including 3 collets. The lasering cost about $5 each.
Several weeks ago one of my grandsons broke his wrist. In a discussion about the accident with SWMBO I mentioned that I had never experienced a bone fracture. (mistake #1).
Some days after that I collected a metal melting furnace from Stuart Tankard. A loan, so I could melt enough bronze to cast the Ottoman bombard. My own furnace has a capacity of 3kg of bronze, but I needed to melt about 10kg for each of the two parts of the cannon. Stuart’s furnace is gas fired and will take much larger crucibles than mine. He readily agreed to the loan of the furnace, but I noted that he hesitated when I rang to arrange the pickup. I discovered why when we loaded it.
It is bloody heavy!! The two of us could not lift it more than a few centimeters. It must weigh around 200kg.
So, we manoeuvred it onto a hydraulic lift trolley, and used that that to roll it to my Landcruiser, jacked it up, and slowly and progressively moved it into the back compartment of the cruiser. I assured Stuart that I would be OK unloading it. (error #2) I have an identical hydraulic lift trolley. And I was sure that I could carefully manoeuvre the furnace onto the trolley.
So, at my workshop I backed the cruiser to the concrete pad where the trolley was positioned, jacked up the trolley platform to the level of my cruiser and slowly pulled the furnace towards the trolley. But it would not budge.
The furnace has a handle for rolling it around. The handle slips into position quite neatly. So I climbed onto the cruiser floor, and started pulling and manoeuvring (error #3). Suddenly, the handle came free, and I was flying through the air tumbling backwards. Fortunately the furnace stayed where it sat.
But I hit the concrete pad.
With my chest.
Initially I was winded. And my chest hurt like hell. And my head hurt. When I stood, I realised that I was conscious, bit giddy, and in PAIN from my chest. Oh shit. I knew that I had probably broken a rib(s). It hurt to breath. I took shallow breaths. No bleeding, but I was sure that there would be some impressive bruises.
As was alone, with no-one nearby, I rang my wife. By then I had regained my breath and I reassured her that I was not seriously hurt, and did not need an ambulance. But if I did not turn up at home that evening maybe she should come and find me. (sensible#)
As time passed, the pain did not seem too bad, so I had a cup of coffee, some Aspirin, finished unloading the furnace, and a couple of hours later drove home. I took some more aspirin, and started cooking dinner as usual. My wife said that I should see a doctor, but hey, I used to be a doctor, and I knew that nothing serious had happened. (error #3). Also it was a public holiday. My doctor would have either been on call, or arranged suitable cover. But I figured that it could wait until the next day.
After an uncomfortable, restless night, the next morning I felt sore, but not in severe pain, and it settled with some more aspirin. We were child minding that day, so seeing the doctor would have been very inconvenient. So I did the child minding with my wife, with no great problems. Then another restless night. I planned to see my GP the next day. Or at least to talk to him with a phone consultation.
Next morning, I sneezed. Hay fever. The chest pain was suddenly much worse. Aspirin hardly touched it. Some movements were very painful. I was terrified that I would sneeze again. Deep breaths were out of the question. I rang for an urgent appointment with my GP. It was made for late that afternoon. I knew that I needed an X-ray of my ribs, so I sent an email to my doctor. It is almost impossible to get to talk directly to a doctor without a prior appointment but I thought that an email from an ex-doctor might might get through. And it did. I had a phone call from him within minutes, and the X-ray was arranged. He also arranged an electronic prescription for a stronger pain killer, which my wife collected. It helped.
I had the X-ray, driven there by my wife, who by this stage was very concerned.
At the pre-arranged consultation the GP examined me. Clinically he agreed that at least one rib was fractured. However the X-ray report said that there was no fracture. He invited me to view the X-rays, and I was certain that I could see a fracture. I was no radiologist but I had seen a lot of X-rays in my medical career. A second radiologist opinion would be obtained. (the second opinion confirmed the fracture). My lungs were intact at that time.
I did not require hospital admission. I was given a prescription for more pain killers, instructions about keeping active, taking laxatives (to avoid the analgesic induced constipation), and to stay in touch for the 6 or so weeks that healing would require.
The next day the situation changed. Despite the strong pain killers, the pain progressively worsened. By evening, when SWMBO arrived home I was having frequent episodes of agony in the area of the fracture(s). I discovered the meaning of the phrase “pain bringing someone (me) to his knees”. It was worse than the root canal pain, the ski accident multiple ruptured ligaments and crushed bone ends pain, you get the picture. I was almost fainting with the pain. SWBMO wanted to get an ambulance. I did not want the delay. So she drove me to the hospital casualty. Every bump in the road provoked the agony.
At the hospital, I staggered into the casualty department while SWMBO parked the car. There was a queue at the triage assessment. I had put on a mask as per Covid regulations. I was doubled over with pain, and wondering if I would faint if a severe wave occurred. I was aware that I was groaning with the pain. Waiting people were staring. But the triage nurse was not looking. So I walked to the window and said “I am in severe pain”. She said “sit there”. I said “I cannot sit down”. She pointed to an adjacent room and said “wait in there”. So I did, while she continued getting details from the two people ahead of me in the queue. I was bothered by the attitude, but in no condition to argue. I guess that she was following protocol. I wonder what protocol would have required if I had collapsed.
Eventually, after an interminable wait (probably about 5 minutes) I was motioned to window, gave my details, and I was walked with assistance from 2 orderlies, into a cubicle. Things moved quickly then. An IV line was inserted, and I was given IV Morphine. A few seconds later the pain was almost gone. It was heaven.
A CT scan confirmed the fractures. And partial lung collapse. My liver was intact. There was no internal bleeding. Hospital admission was recommended, and SWMBO insisted that I accept, although after the Morphine I was tempted to go home. Anyway, I stayed overnight, with strong oral painkillers every 3 hours.
I was discharged home the next day with a supply of really strong painkillers, and arrangements for follow up. Since then, I have been slowly improving. I have a strange “clicking” sensation at the site of the fracture. Something is moving. Yesterday I visited the workshop, but not really up to anything interesting. Doing a lot of dozing.
I started with virtually no knowledge about this subject, but I had to learn quickly in order to finish my 1:10 model Armstrong rifled muzzle loading 1866 cannon. I finished the job, not perfectly, but adequately, and this is what I have learned so far.
Copper rivets are annealed when purchased, but as soon as you start hammering them, they harden.
You need one hand to hold the work. If you use a hammer, and hold a snap, that uses 2 hands. So either use a third hand or use a pneumatic hammer with the snap attached. That leaves a hand free to hold the job. The pneumatic hammer size must be appropriate for the job. I purchased one from the country of Taiwan. It cost $AUD120. Seems to be excellent quality.
The compressor pressure is critical. The air setting on the hammer is critical. Experiment on waste material first!
Hold the fixed snap in a strong vise.
The snaps need to be accurately made for the rivet size. Try them on waste material before using them on the job.
Rivets of the same size but from different manufacturers will differ in finished appearance. Get your rivets from a single supplier in one batch. Order 10-20% more than you think that you will need. You will lose some, and muck up the insertion in some.
The surface of the snaps should be smooth, with rounded edges. A polished finish is best.
A complex job, with internal rivet ends, requires custom made snaps. Be prepared to make them. For the carriage parts I used 5 different shaped snaps. For copper rivets, mild steel snaps were quite adequate.
Some rivets will not insert well. Just remove them, and try again.
To remove a rivet, grind off one head. It might then push out with a steel pin. If necessary, drill through the shaft with a small drill (say 1-1.5mm for a 2mm rivet), then punch the remains out of the job.
The rivet length must be precise. The head which is formed by the snap was best if the shaft length was 2.5mm longer than the total thickness of the materials to be joined. There are tables to determine the lengths.
To shorten copper rivets, drill a hole in steel plate which is the exact thickness of the desired rivet length, the exact diameter of the rivet. With the rivet in the hole, snip the rivet to length with wire cutters, then belt sand it to length. Push the rivet out backwards.
With grateful thanks to Neil M for expert advice on this subject.
The lettering on the muzzle reads “Marshall’s Iron”. It refers to the steel bore of the barrel, which was supplied to the Royal Gun Factory by a specialist manufacturer, Marshall Iron. The rest of the barrel was made from wrought iron, as a coil, as described in a previous post.
The barrel is 300mm long, too high for the laser machine to focus. So the setup used a low profile 3 jaw vice, hanging out from the edge of the machine, with the breech of the barrel down the front of the desk/bench.
Immediately after lasering, which took about 20 seconds, (and about 45 minutes to set up the machine/supports). The circle represents the junction between the steel bore and the outer iron coil. The vertical line was used for sighting.
The lines and lettering looked a lot sharper after a quick rub with emery paper. Those letters are less than 1mm high. A very magnified, not well focussed photo.
The cannon is now mounted on a shiny acrylic/wood base. It reflects the underneath details. And has handles.
Thanks once again to Stuart Tankard, for using his fibre laser machine to accomplish the engraving. Stuart told me that he has done more jobs for me than he has done for himself. I call it “getting experience”.
And, WordPress has now improved its program to the point that captions cannot be added to photographs, and a title cannot be added to the post. Well done WordPress. (p.s. 16 June… captions and headings have reappeared. Hooray!)
I have been tearing out chunks of hair, and gnashing teeth because prints are failing due to loss of adhesion. And the problem has progressively worsened to the point that the failure rate is now 100%.
And I am thoroughly fed up with throwing bird’s nest conglomerations of PLA in the bin.
I have tried the following remedies…….
Varying the bed temperatures and extruder temperatures up and down. Various combinations and permutations.
Cleaning the bed after every print, with acetone and scraping.
Checking and rechecking the bed for level.
Replacing the extruder nozzle.
Changing the PLA to brand new stock.
Printing on a different part of the bed rather than the default centre.
Today, I searched the net for solutions, and I decided that I had tried all of them, EXCEPT, replacing the bed surface.
I have been using a 3M product, designed for 3D printing, designated 9080A. Today I RTFM. If you do not know what that stands for, try “Read the F’ing Manual”. So I RTFM’d.
It seems that 9080A is good only for 10 uses, then should be replaced. OK. Penny drop time. I have been using the printer for 18 months with the same 9080A sheet. Maybe 50 times?
Back to Amazon, order some more 9080A sheets. Meanwhile I will revert to the borosilicate glass sheet that was originally supplied with the printer.
Well, 99% finished. I still intend to make sights, a base, and bumper components. But it now looks finished. A few pics.
It has a few differences from the first one of these which I finished for last Xmas. It has side platforms, handles for positioning the carriage on the slide, minor design changes in the rear wheel brackets, minor changes in the elevation wheel, and probably a few more that I cannot remember.
The explosive projectiles would never have been placed on the side platform. The noses contained impact sensitive detonators, and I doubt that the gunners would have risked them falling off.
The positioning gears work well, as does the elevating mechanism/gears, the elevation lock, the clutch and brake.
Oh yes, some fasteners for the rear platform too… And engraving text on the recoil tube cap, and the muzzle mouth. OK, 98% done.
Now, I am getting on with my next project too. Yes I will eventually finish the Armstrong RML cannon. But I am getting impatient to be doing something different, so I have started on the bronze version of the Ottoman bombard.
This PLA 3D printed breech is 230mm long, plus thread, and 107mm max. diameter. Still deciding whether to refine the design and print another. For one thing, the threaded section is constant diameter, whereas the original had a tapered thread. Yet to 3D print the barrel. It is 280mm long. That is a lot of plastic to burn out prior to bronze pouring. Maybe I should use transparent PLA in case the black dye (whatever it is) damages my burn out oven, or my lungs.
For another thing I have been unable to get my CAD program to convert the Ancient Arabic Script into vectors. But, I have been able to get V-Carve Pro to recognise them/
That is a tracing from the photograph. A couple of hours of effort doing the tracing. Then scanned the tracing, and imported the scan into V Carve. That worked, and I hope to remove 0.5mm of the muzzle bronze, leaving the raised script and stylised designs. V Carve predicts that will take 5 hours on the CNC mill!! Watch this space.
Almost finished the model Armstrong 80pr RML, and just starting another project. I have mentioned it in previous posts…. a 1:10 scale model of the 17 ton Turkish bombard, which currently resides at the Royal Armories Museum, Fort Nelson, Portsmouth, UK.
The original was in 2 pieces, to make the casting process manageable, and presumably to make transporting the monster cannon more manageable. The museum states that another reason for the screw thread join of the 2 massive parts was to separate the halves for reloading, but I can find no substantiating references for that statement. And it does not make sense to my conception of what would have been involved in the reloading process.
At 1:10 scale the model will be over 500mm long, and will presumably weigh approximately 17kg (37.5lb). Each piece will weigh 8-9kg. I will make the model in 2 pieces, for authenticity, and to make the casting more manageable, and to make the 3D printing possible. My 3D printer has a maximum model size of 300x300x400mm.
I spent several days drawing up the breech and saving it as an stl file, for the slicer (Simplify 3D) to process. The slicer predicted that the print would take 51 hours, and consume 697g (1.5lb) of PLA. I used 0.2mm layers, with 8 top, 8 bottom, and 6 side layers, and 10% fill, and since there wee some 90º overhangs, I decided to add supports.
And guess what. The print took 51 hours, and consumed most of a 1kg roll of PLA.
I chose to operate the extruder a bit hotter than normal, at 225ºc, and heated the platen to 65ºc. I wanted to make sure that this print was water tight for the moulding process, and remained adherent to the platen for the duration of the print. I accepted that the detail of the print surface would be a little coarser than could be achieved at a finer layer thickness, but the benefit would be increased water tightness.
I am still drawing up the barrel. Well, actually, it is fully drawn up, but I am refining the drawing of the Arabic script which is embossed on the muzzle. It is quite difficult to convert the squiggles and patterns to vectors, which can be used to produce the STL file for the 3D printer.
So, firstly the cheap epoxy repair/filler. I paid $AUD9.95 for 100g on Ebay.
I had dropped a tool onto my cheap compressor, and snapped off the muck metal outlet fitting. I tried cutting off the broken bit, re-tapping it, and blocking off the broken bit, but the muck metal part kept on crumbling away.
So, I filled the broken fitting with the Chinese epoxy.
It took many hours to set hard, and I left it for 24 hours before firing up the compressor. I stood well back, out of the firing line, and powered up at 100 psi. All good. So I left it for a few hours, still all good. So then I did some riveting on my model cannon….
The Chinese epoxy metal repair-filler is inexpensive and works well. Just a pity that it comes from a country whose government ignores international laws, and is territorially aggressive (Tibet, Taiwan, Tajikistan, South China Sea). And has probably lied about the origins of the Covid pandemic.
Camping on the bank of the Murray River was just sublime. Good weather, beautiful surroundings, quiet and solitude, wildlife, brilliant night skies and endless blue day skies, exploring the Hattah Kulkyne National Park and Sunset Kulkyne National Park. Swimming, campfire cooking, good wine and good company.
But all good things come to an end, and wet weather was on the way, so we packed up, and set off home. First step was to negotiate the awful entrance track. 20-30 minutes of vehicular destruction and bone shaking. Off track driving is strictly forbidden to protect the easily damaged vegetation, but boy was it tempting.
We took a longer route home, involving an overnight stay in the western Victorian town of Horsham. That was so we could be at the opening time of the Stick Shed at Murtoa. See my post “Now, This is a shed” March 20 2021. And the route was chosen to see as many wheat silos as possible. North Western Victoria varies from desert to dry country, and the dry country is mostly used to grow wheat. Tall concrete silos dot the towns and countryside, and many of them have been painted.
The paintings typically take 2-3 months to complete. Cost was not disclosed, but the increased tourism has more than justified the cost. We did wonder if upkeep of the paintings had been factored in.
Returning to model cannon next post. Riveting stuff!
During our 5 days camping on the bank of the Murray River our movements through the 48,000H hectare Hattah Kulkyne National Park were restricted for 2 days because feral goats were being culled by helicopter shooters. Movements along the River Track were permitted, and we never saw or heard the helicopter. On one of those days we drove to Hattah (population 28), then into Sunset Country – Murray Sunset National Park. We drove west, then south to The Pink Lakes, then via Underbool and Ouyen back to our camp on the river. It was a full day trip mostly along rough sandy tracks, and rough dirt tracks. It would be possible in a 2WD, and was easy in the 4WD Landcruisers. It is desert, with no fresh water, except for some tank water at a couple of camping grounds. The lakes on the map are all shallow salt pans. Any water in these is very shallow, and unusable.
Des had never driven a 4WD before, but he quickly gained confidence in the Landcruiser’s predictable handling over the rough sandy tracks, and eventually I had to slow him down. The sand was deep sometimes, but never quite requiring tyre pressure reductions. We saw no other people or vehicles in the park and the camping grounds were empty. We did see some kangaroos and emus on the east side, nearest the river, but no wild life or birds deeper in the desert park.
When our youngest daughter was old enough to be slightly responsible, our family frequently went bush camping on the banks of the Murray River, where it flows through desert country.
No facilities. Just river banks for the tents, the river to swim and fish and yabbie, cooking on campfires. We took a chemical toilet which was located behind a canvas screen. We took drinking water in 20 litre containers. In summer, occasional days were very hot, up to 44ºc. Too hot to be outdoors or in tents. We would drive about an hour and a half to Mildura to shop in air-conditioned centres, or see a movie. But mostly the weather was warm and lovely. Rain was occasional, and could be very heavy.
Often, our family group (2 or 3 families) was the only occupant of the river bank. Sometimes there would be another family group, but privacy was respected, and tents were positioned as far apart as possible. There were friendly nods when passing on the 4WD tracks, or the beach. Yes, there was a beach. At Ki bend, there was a sandy beach about one kilometer long, and 50 to 100m wide, depending on the river height.
A 4WD vehicle was desirable due to the rough access tracks, and essential after rain. The river flood plain was fine clay, and incredibly slippery when wet. Recovering bogged vehicles was a common occurrence. After a few trips I progressed to a Landcruiser with a Warn winch, compressor, snatch straps, tow straps.
The river banks were populated with River Red Gums which extended for a kilometer or 2 away from the river. The red gum dead timber made for long lasting and hot camp fires, ideal for cooking, and evening socialising. The kids quickly learned fire common sense. My youngest became obsessed with fire, and would feed sticks, and watch the fire for long periods. She is still fascinated by fire. (that is the daughter who spent a day with me melting and pouring aluminium to make cannon parts.)
The nights were dark and clear, and we always were blown away by the brilliant night skies. Sometimes I would set up a telescope, or use binoculars, to talk to the kids about stars and constellations, and the moon. We could see the International Space Station quite clearly with the telescope.
The wildlife was wonderful. Large groups of kangaroos and emus. We counted 2000 roos one day! Goannas, and an occasional snake. Wild goats and pigs were visible on the opposite river banks where there was no road access. A half hour drive away there was a ranger station at Hattah, and we would always introduce ourselves to the ranger, and chat about the park.
And the birds! They would start up at dawn, and the squawking was deafening. Sleep was impossible when they commenced. Thousands and thousands of white cockatoos, hawks, eagles, parrots, budgerigars. They would fly off in groups, and return at dusk. Large birds would skim the water and occasionally plunge for fish.
Some days we would cook, eat, swim, play bocce or cricket on the sand, read and read and talk and talk. The kids mostly entertained themselves. The water was shallow and gradual off the sandbank. But we always watched them closely. The Murray is notorious for drownings. There are many submerged dead trees, and the river is constantly flowing.
Other days we would drive through the park to spot animals. And we would have day trips into the Sunset Country. That is true desert. The only water is in salt pans. The trees are low and scrubby. There are many sand hills. Some cattle farms struggle to exist on the margins. There are some operational and some abandoned mines for mica and bentonite. And abandoned iron machinery lasts for decades in the dry environment. We always take 2 vehicles, 4WD’s, in case of breakdown, or irretrievable bogging. And containers of water and food. 4WD is essential in some places due to loose deep sand, where the going is slow, careful, and heavy.
These were wonderful family holidays. When my daughters grew into adults and left home to make their own lives, the Hattah trips stopped, but they often reminisced about camping at Hattah. Lately they have been talking about taking their own children, my grandchildren, camping on the banks of the Murray at Hattah.
Then recently, my brother in law and his wife asked me if I wanted to join them on a nostalgic trip back to Hattah. I immediately agreed, and invited another friend to join us. My wife used to love the camping trips, but her arthritis limits her mobility, and sleeping on the ground is not an option for her. Even an offer to hire an off road camper was not acceptable. So I asked a friend who had never been bush camping, and had never done any off road driving. I was somewhat surprised when he immediately agreed. We are all into our 70’s. My vehicle is still an 80 series Landcruiser, 27 years old. But it is in good mechanical condition. Bull bar, Warn winch, heavy duty springs, compressor, dual batteries, driving lights, and I still have lots of recovery gear. I also still have a “minute” tent, small fridge, cooking gear, etc etc. It was all stored away in case such an occasion would arise. I also packed my anti snoring CPP device, medications, a first aid kit. And I bought a modern innovation, a solar blanket, for recharging the vehicle batteries, to keep the fridge, and my snoring device working. The fridge was for beer, meltables and vegetables. I am now vegetarian, so keeping meat chilled was not an issue.
I also purchased a pair of hand held small walkie-talkies, for communication b