Before I am hung, drawn and quartered, for operating a lathe without guards, here is the proof that I have been sensible.
Before I am hung, drawn and quartered, for operating a lathe without guards, here is the proof that I have been sensible.
First Test Run
After some test runs without tool or material, I performed some measurements.
500mm movements along the Z axis were reproduced multiple times with a deviation of 0.00mm! (the Z axis has a ground ball screw)
100mm movements along the X axis deviated 0.02mm. (the X axis has a rolled ball screw).
I was delighted to note that the lathe is extremely quiet and smooth. The only noise is some belt slap from the very old belts, and from the stepper motors.
The video below was taken from my iphone, while I was operating the lathe controls, so please excuse the erratic movements.
The steel is 27mm diameter. 750rpm, 50mm/min feeds.
And the guards will be made next step, without fail.
The G code was generated using Mach3 for these very simple shapes. For more complex items I use Ezilathe.
The lathe is 600mm between centres. 38mm spindle bore. Swing about 300mm.
Knowing that I have an interest in CNC machining, Tom, from the Vintage Machinery Club in Geelong asked me to make a pair of oilers for a very old Wedlake and Dendy steam engine. The engine is a large (to me anyway) stationary engine, which is run on steam several times each year. The oilers for the cross slides were missing.
We searched the Internet for pictures of W&D steam engines, but could find no pictures or diagrams of the oilers. So Tom sketched a design, and I drew a CAD diagram. The dimensions were finally determined by the materials which I had available… some 1.5″ brass rod and some 1.5″ copper tube.
This is the almost finished product.
The oilers work by wicking the oil from the reservoir into a tube which drains through the base onto the engine slide. When the wick tubes are fitted the oilers can be fitted to the engine.
My lathe is a Boxford TCL125, using Mach3. The G code is generated using Ezilathe.
Below is a link to an oil cup from “USS Monitor”, of American civil war fame. One of the first ironclads, powered only by steam.
(ps. The lathe which I was converting to CNC was the subject of previous posts and is now working, but needs some guards fitted and a bit of fine tuning.)
This mechanism was discovered in 1901, in a Roman era shipwreck, off the Greek island of Antikythera, which is a bit north of Crete.
It has been dated to between 100BCE and 205BCE, with the older date considered the best estimate. ie, about 2200 years old. Experts believe that its makers were Greek.
It is currently housed in the Greek National Archeological Museum in Athens.
Look it up on Wikipedia..
According to the Wikipedia entry the gear teeth are too irregular to have been machine cut,
but watch the computer reconstruction. Could you make this machine without a lathe and gear cutters?
How much more technology did the ancients have that has not survived the ravages of time? A lathe for example.
I recently had a light globe switched on in my brain.
I was holidaying in Athens (the one in Greece), and was gobsmacked by the huge, fabulous collection of statues, mosaics, ceramics, gold jewellery and masks, bronze and iron weapons in the National Archeological Museum. I took many photos, and might post some in later blogs.
Three items sent shivers down my spine.
There was a display with many surgical instruments. These have been found at various archeological digs in Greece, and while not precisely dated (at least not labelled) they are mostly from 500-200 BCE.
My eye was immediately drawn to an instrument which looked very familiar. I was a gynaecologist in my previous life, and this could have come from my instruments. (except that the dark bronze surface might not have been acceptable to patients).
The instrument is labelled a vaginal dilator, but I am quite certain that it is a vaginal speculum. A speculum is used to inspect the vaginal walls and uterine cervix. (That might be too much information my metal working/ engine making/ machinery minded readers. If so, too bad.)
It is said to be made of bronze. The Ancient Greeks were highly skilled at metal casting, as evidenced by the many complex and beautiful bronze statues and weapons and implements on display.
It interested me for several reasons. Bear in mind that not many archeology museum visitors are gynaecologists who know about making threads in metal.
It looks quite functional, and if cleaned up, given a shiny surface and sterilized it could be used today.
The threaded section is very regular and smooth. I would loved to have taken some measurements of the thread with a micrometer, but had to be content with a prolonged inspection through the glass case. The thread appears to me to be so regular, that it could not have been hand filed. It must have been machine made. I have seen hand made threads on medieval machines, and they are crude compared with this one.
Either this is not an ancient Greek instrument but a more modern instrument accidentally included in the display (pretty unlikely, considering the professionalism of the people involved). (ps. If you Google Pompeii speculum, you will see that similar instruments have been unearthed at Pompeii… buried since 79ce.)
Or….. the ancient Greeks had screw cutting lathes.
Ridiculous you say?
Wait until my next post about the Antikythera machine. If if you just cannot wait, look it up. It is mind blowing.
Compressed air is very, very useful on the milling machine. The tool changer uses air for fast tightening and release. And I often use air to clear the field of swarf, and shavings (yes, I use my mill for wood too).
Recently, at the suggestion of Stuart L of stusshed.com fame, I installed 2 semipermanent nozzles on the mill, with adjustable direction and pressure adjustments. It has been a quantum leap improvement.
The pic shows the jets aimed during CNC end milling of wood. The wood shavings are blown away which makes it easier to see how the milling is progressing; blows them away from me which is safer and cleaner; and stops the chips being machined into the work, which leads to a cleaner cut. It also improves any video or photo of the progress. It must also cool the cutter, although not as effectively as a liquid coolant. I have not tried using the misting attachment, which would improve the cooling, but at the cost of dampening the area and the work.
I particularly like the improvement experienced when machining brass or steel. The swarf is removed from the advancing cutter, preventing it being re-machined and squashed into the workpiece. I am noticing better surface finishes. I also adjust the air direction to keep the swarf away from me; particularly valuable when brass needles otherwise would be flying at me.
When cutting pockets, the air keeps the pocket free of swarf, and when using tiny endmills at high speeds I am experiencing fewer tool breakages.
This gadget was inexpensive ($AUD12) from China. It does not work the compressor too hard when the volume is turned back as far as possible, but still adequate. Although there are 2 jets, I find that only one at a time is adequate.
As an afterthought. I rarely use coolant on my lathes, but an air stream on the cutter and workpiece would probably have similar advantages to those listed above. I particularly wonder if it would assist during deep parting… always a tense procedure. I suspect that the cutter becomes hotter and expands more than the workpiece parting slot if there is no coolant. I will mention the result of air cooling and chip clearing on the lathe in a later blog.
To continue the posts about making the seismic wave generator. See the previous post about water jet cutting the steel plates.
From what I am told, the generator is positioned, pinned to the ground, and hit on the ends with a sledge hammer. Instruments pick up and measure the seismic waves in order to analyse what is beneath.
Sound is not required. In fact sound is annoying and a disadvantage.
The operator stands on the generator while swinging the hammer.
So here is the finished item, ready to be delivered. It weighs 20kg.
It will be interesting to hear how it performs.
Click on the arrow in the screen link below to connect to the YouTube video of the making of the 1779 model cannon. Probably of interest only to machine aficionados, but it does feature some very pleasant music composed and played by Lis Viggers.
The labels appear too briefly, so use the pause button to read them.
The segment on boring the barrel is really boring. (really)
And a few editing errors appeared. I typed cascobels when it should have read astragals. Not prepared to delete, re-edit and re-upload given my very slow Internet connection.
And this is a link to another YouTube video with an excellent description of how these type of cannons were made originally. Definitely worth watching.
The 1779 model naval cannon is complete, finished!
Photos of finished project in next blog.
The last task was to make the bolts, hinge and keys which hold the barrel to the carriage.
These small items took 2 days to make, demonstrating that the size of parts has no relation to the the time taken to make, except in an inverse relationship. ie. the smaller the part, the harder and longer it takes to, make it.
The bolts which hold the barrel trunnion to the carriage have small rectangular holes which hold a key. The holes are 2.4mm wide and 3.6mm high. That is smaller than my smallest file. My smallest endmill is 2.38mm diameter, so that determined the size of the rectangular holes.
I drilled the holes with the endmill, then elongated the round hole to a rectangle by filing.
The problem was that my smallest file was a square file 3x3mm.
Solution! I ground the teeth off two surfaces of the file, leaving 2 faces 2.4mm apart, and 2 cutting faces 3mm apart. (using a surface grinder).
Then I had to make the keys. These are truly minute!
So I cheated. I CNC’d the shape on the end of a piece of brass rod, then parted off the keys in the lathe.
Another couple of long and very enjoyable workshop days, making various bits for the 1779 24 pounder model naval cannon.
As you can see, this cannon project is almost completed. A few more hours to make some bolts and fittings. I am considering adding some ropes and pulley blocks.
I am unsure whether the trunnions are the semi circular holes in the carriage, or the cylindrical bits of the metal barrel which support the barrel. I am going to assume that the trunnions are the part of the barrel. (I checked. The trunnions are the cylindrical parts of the barrel which support the barrel.)
So, today I made some trunnions and silver soldered them to the barrel. In the full size original version they would have been part of the barrel casting.
But before that, I polished the barrel with a Scotchbrite type pad, impregnated with some polishing compound. And it made the barrel sparkle!
Then I attached the knob at the breech end, M4 threaded rod attachment.
Today the exterior surface of the model 1779 naval cannon barrel was turned.
The piece of brass material weighed 5.1kg, was 300mm long and 50.8mm diameter.
I had used Loctite to glue a spigott in the bore, to provide a center and a driving diameter which the small CNC lathe would accept.
Although the lathe was nominally 300m between centres, the toolpost would move only about 200mm. So the turning had to be accomplished by turning the cannon mouth end first, and then reversing the workpiece to turn the breech end.
The CNC lathe, owned by Bob Julian, is about 30 years old, and it came out of a school. In the course of this job, it seemed to progressively free up, making us suspect that this is possibly the first time it has ever been seriously used.
The lathe electronics had been replaced by Stuart Tankard to use Mach3. The G codes were generated by Stuart’s program “Ezilathe”, which is available as a free download on “CNC Zone”. It is an excellent CNC lathe program, and I thoroughly recommend it.
I will eventually post some videos of the turning progress, but my Oz internet connection is so slow, that for the moment I will post photos only.
I started by turning a piece of rubbishy pine as a test.
The starting weight was 5.1kg. The end weight, including the spigott was 2.9kg. So at least 2kg of brass swarf, most of which I swept up and saved for possible future use.
Next to machine the trunions and some silver soldering.
I decided to buy another metal lathe. For a few years I have been using a Chinese heavy duty machine, a GBC, which was 1000mm between centres and a swing of 400mm. It is a heavy duty machine, weighs 2 tonnes, and does its job. For turning large objects, up to 400mm diameter, and taking off large amounts of swarf quickly, it is excellent. But I must admit to a lack of pride of ownership of this machine. Particularly after being exposed to British workmanship in my small Boxford.
So I had a look around, and settled on a Colchester Master 2500. It is less than half the weight, and physically smaller, although the work dimensions are similar to the GBC. I persuaded SWMBO that if I sold the GBC, the small Taiwanese lathe, and the 2 Smart & Brown lathes which I had restored (see earlier posts), I would just about break even, have more space in my workshop, and there would be less stuff for her to get rid of if I happen to cark it at some inconvenient time. Also, the Colchester should not be difficult to resell. It has an excellent, almost legendary, reputation, and as I discovered, commands high second hand prices.
This process was actually jogged by seeing a Colchester on ebay which was of interest. It was cheapish, no bids, and the photos were awful quality. So I rang the owner. He had bought the lathe 3 years earlier, but had never used it because he did not yet have 3 phase power. The owner before him had used it to make hinges or something similar, as a backyard industry, and before that it had been in a school. In my experience, school lathes tend to show little wear, but often show evidence of crashes. The owner sent me photos of the bed, which did show dings from crashes, but nothing terrible.
So, full of optimism, I hooked up the tandem trailer to the old Landcruiser and drove the 250km to the other side of the state. To cut the story short, the lathe looked OK, but when I removed the gearbox cover, first the oil was old, black, and thick, one gear had a tooth missing, and another was severely worn. I took the owner at his word that he did not know about this condition (possibly correct), thanked him for his time and went home. It had been a pleasant drive.
(note added 23 June 2015. The seller is still advertising his lathe, same price, no mention of the broken and worn gears. I am inclined to think less charitably about someone who would let a buyer drive 500km and not be honest about the item being sold.)
Next stop was a machinery second hand dealer. They had 7 Colchesters, from a University workroom closure. They were much more expensive, had been nicely cleaned up, had all of the chucks, steadies, tool holders, manuals etc. I did seriously consider one of these, which had a few dings on the bed, but otherwise looked good. I decided to sleep on the decision.
Next day, I visited two more ebay sellers with Colchesters. I have racked up about 800km looking at possibilities. The first was from a factory close down. It was dirty, old, and had only a 3 jaw chuck. Despite its industrial past, it showed little visible evidence of wear. But the reversing handle would not stay engaged. No big deal according the owner, just a spring to be replaced. Hmm….. The price was OK, but not negotiable. I would think about it. Quite tempted with that one.
Then a tollway trip to the other side of Melbourne. My last option. In case you were wondering, this plethora of Colchester lathes is very unusual. I have been looking for this model for about 2 years, but have never seen more than one Colchester Master 2500 advertised within striking distance at one time. So having 7 or 8 to examine has been fantastic and unusual. Maybe everyone is wanting CNC these days.
The last one was an ex Department of Defence machine. It was midway in the price range, but negotiable. I could not fault it. It was tight, no dings at all, had clean oil in the gearbox, gears all intact, and had a full range of chucks, faceplate, tool holders, steadies etc. No manual. Needs a repaint. Probably 25-30 years old. (note added 23/6.. more like 45 years old!) Being DOD, it would have been fastidiously maintained. So what was the catch? I could not find one. I negotiated a lower price, and shook hands.
Next to pick it up. Then to sell my existing lathes.
Watch this space.
Apart from contending with fauna in my workshop (a tiger snake) , I did actually make some progress today.
Today I assembled the base, columns and Jig, intending to mill a flat top to the whole assembly.
To my surprise and dismay, it was apparent that one of the columns was one mm out of position. Dont know how that happened. A typo in the CAD drawing or CNC program? It could not be a zeroing issue, because all 3 columns on that side would be out of position.
What to do?
I decided to turn the 2.5mm holes in the column base into slots 3.5mm long. The bolting position on the jig was exactly correct, so I used that to zero the position, found a 2.5mm end mill, and gingerly milled the slot. holding the column upside down in the milling vice.
Fortunately, that seems to have worked. The columns are now all correctly located. The tops of the columns are the crucial plane and position, and they seem good. I doubt that the slots will be an issue in the finished engine. They are invisible under the column feet. If necessary, I will make a couple of locating pins and drill them in position right through the base from underneath. I doubt that will be required.
After that, I did take a milling skim off the column tops, to create a dead flat plane, to which to bolt the cylinder bases, when I have made them.
Not tomorrow though. I am off to Ballarat Victoria to a swap meet on the aerodrome. In previous years there have been approximately a thousand stalls. Some are shed clean outs, some commercial vendors and dealers, and lots of ancient cars and machinery and parts. The best stalls are the ones selling used tools. I seem to come home after each meet with a heavy pack full of tools and materials, and a lighter wallet. But it is always interesting and fun.
Today I made the BA7 studs for the columns on the triple expansion steam engine. I decided to use 25mm bolts, then trim them to length after they were installed into the threaded holes. Why not use threaded rod or make my own studs on the CNC lathe I hear you asking? Well, I could have made my own studs. In fact I did make 2 studs, quite succesfully. But it was time consuming. Cutting up threaded rod would have worked, but it turned out to be less expensive to buy over length bolts which are threaded right down to the heads, and trim them to length, than to buy threaded rod. Plus, the trimmed bolts are now quite useable 12mm bolts. Also, it was easy to use the bolt hex head to screw them into the threaded holes.
I did manage to break off one stud and spent a half hour or so digging the stub out and renewing the stud. But no permanent damage.
This is the project which has kept me away from the engines and lathes lately.
SWMBO suggested that maybe I could put all of those expensive metalworking machines to some practical use by making some gates for her current project, which is a house renovation.
Recently retired, and therefore with no reasonable excuse for declining, I had to say “but of course”. The option was to get a professional to make and hang the gates, but I could not think quickly enough of an excuse that would be persuasive. Wanting to get back to the triple expansion engine and the TNC lathe just would not cut it. Cutting and welding steel in our Australian summer is usually a big No No, due to the risk of fire. But we are having a relatively cool summer so far, after a very dry spring, so there is very little fuel around my sheds making the fire risk not too huge.
The fence has 40mm galvanised iron posts, and the fencing material itself is welded galvanised mesh. It is only 900mm high, typical for the houses in the area. The original gates were rubbish, so I removed and scrapped them. The previous owner had removed a section of fence to allow access to the back yard, so 2 sets of double gates were required.
My architect wife decided that the original style of fence and gates should be retained. I think that the style is termed “industrial boring ugly”, and has no function except to mark the boundary, and maybe to keep a very small dog, and/or child, off the street. But mine is not to reason why…….
So I measured the openings, roughly guessed the fall over the openings at approx 50mm, and sketched an elevation. Not complicated. I allowed 25mm for the hinges and 25mm for the centre gap. Bought the galvanised steel pipe (4 lengths of 6.4m x 33mm) and ordered the mesh to match the existing fence mesh. The steel merchant obligingly cut the steel lengths in half so I could carry them on my roof racks. Also some cold gal paint, and pipe caps. Total cost … $A370. The mesh panels came only in 2.5 meter lengths so I could get only one gate from each length, with a meter of waste from each gate. But I guess that the waste will be used somewhere. It would make reasonable reinforcing mesh for concrete. Or maybe a personal entry gate.
Measuring, planning, and buying steel had comfortably occupied a couple of days (that’s when I managed to get some paint on the little lathe), but SWMBO was getting impatient for some real action, so I cut up the steel.
The verticals were easy, All 800mm. Cut one, and used it as a standard for the other 7 verticals. The biggest problem was manoevering the lengths of pipe in my now overcrowded workshop. The drop bandsaw quickly munched through the medium weight pipe.
The horizontals were a bit more complicated. There are 3 possible methods of joining pipe where the horizontal butts up to the vertical.
The first simply makes straight cuts and the horizontal ends are flattened to permit a weld to the vertical. This is the method most often used on the farm, but it is a bit “agricultural”.
The horizontals and verticals could be cut at 45 degrees and mitre welded together. Not quite the look desired.
So I cut the horizontals with a hole saw which is the same diameter as the pipe, resulting in a very neat fit to the vertical. I had not used this method before, but it looked feasible. The pipe was held in a milling vice and the bi-metal hole saw was attached to the drill press. Using a slow speed (200 rpm), cutting fluid, and a slow feed rate, all went well.
The verticals and bottom rail were welded together. I used a MIG welder, and chose to burn off the zinc galvanizing during the welding rather than grind it off. That is a bit quicker and messier than grinding. I cramped the pipes to be welded to a thick bit of plywood, to minimise distortion and keep the 90 degree angles, and also to keep the frame as flat as possible. A steel welding bench would be better. And yes I did need to put out a few small plywood fires.
The mesh was cut to size using bolt cutters. The top rail was welded into place, after feeding it through the mesh (see photo). The mesh was then welded to the frame.
The welds were then all wire brushed clean and sprayed with cold gal paint. (a zinc rich paint which looks similar to galvanising).
I forgot to mention that the pipe hinges were put onto their respective verticals before completing the welding of the frames. Actually I forgot the hinges on the first frame, so I had to cut a weld to place the hinges, then reweld. Stupid, but I made that mistake only once.
So, back to the site to weld the hinges to the posts. But by now it was 34 degrees (centigrade), and the sun was fierce. I could have proceeded, but my glasses were steaming up, I was tired, hot, and bothered, so I dumped the gates and decided to wait for cooler weather.
Today (2 days later) was a bit cooler, so Tony (my blacksmith friend) and I welded the gates into place. Vertical up welds are a bit beyond my expertise, so I was happy to enlist an expert. (Thanks Tony).
So, almost finished, rather boring, thanks for bearing with me. John. More on the triple expansion next blog, promise.
I CNC’d a new handle to replace the broken one on the little lathe, but the new one made the old ones look a bit shabby, so they will all be renewed. The new, deeply waisted handles are very nice to use.
The headstock shaft was 3/8″ and was a bit undersized due to wear, and I intend to use a collet chuck with a 10mm shaft, so I decided to increase the shaft size from 3/8 (9.525mm) to 10mm.
The headstock bearing housing is split, to permit some adjustment with wear. I used a reamer with spiral teeth to avoid the teeth snagging the split. And all seemed to go very well using the setup in the photo below.
…Until I finished and raised the milling machine head out of the work.
Due to my lack of familiarity with the CNC mill controls I activated the X axis rather than the Z axis. The side movement broke the reamer and partially gouged the newly reamed lowermost housing. Bugger. Bugger.
What to do. Throw the whole project into the scrap bin? (following a few others). Change the shaft to the next size (12mm) and enlarge the housing holes to 12mm? That would thin and weaken the housing. And would be tricky machining. Also, due to the damage in a lateral direction caused by the mishap, I was not sure that drilling and reaming, or boring and reaming, would not follow the same lateral path.
At least the uppermost housing was undamaged, so whatever tool was used would be held concentrically, as long as the cutting edge extended the distance between the 2 housings.
So I very slowly drilled 11.5mm (the 11.5mm drill did span the distance between the 2 housings) and re-reamed to 12mm, again as per the above photo. Despite my misgivings, this time it all went well. The 12mm shaft is rather tight, and the housings will need some lapping. The housings appear to have enough thickness remaining, but time will tell in that regard. The lateral direction of the shaft is not perfect, but in such a small lathe that is not a big consideration.
As a consolation, and to retore some self esteem after this muck up, I made a new chuck key.
The chuck is held onto the shaft with a 3/8″ x 24tpi thread. That thread was cut on the CNC lathe, and is probably fairly accurate. The oil cups are spare from the beam engine build.
I plan to lap the housings, install a thrust bearing behind the chuck, and make a drive pulley. I have a spare 12mm shaft ER 16 collet chuck, which will probably be used more often than the 4 jaw chuck. Then a new handle for the longitudinal feed, a paint job, a motor and belt…