The anvils for the English Wheel are done!
It wasn’t quite as quick as I’d hoped but it wasn’t that hard.
In contrast, the EN8 steel is quite hard. The first couple of cutting tips and turning speeds simply resulted in blunt tips. Cutting through the EN8 stock on my band-saw took a new saw blade every 4 cuts. The saw blades didn’t snap, but when they got slightly blunt, in this hard steel, the cut slowed right down and had a tendency to wander, pulling the blade off its runners every 2 seconds. Cutting it by hand would be a few hours hard work, per anvil.
The cutting speed I ended up at, seemed way to slow to me (85rpm) but what do I know? I write code for a living! It worked, so who cares? I didn’t use a carbide steel cutting tip – just plain ole’ tool steel. For sanding and polishing I used 1500rpm. For filing I used 60rpm, any faster and the file shuddered or ‘kind of’ bounced on the work-piece. Starting the filing got easier as the piece got smoother. When you first touch the file onto the piece, can be when the deep scratches appear. I found an old chart that said the sfm for EN8 (1040) should be between 55 and 175. I think?!? it actually turned out to be about 70. I used a feed that looked around 0.5 inches per minute (IPM).
Turning Speed and Feed Calculator
The easy anvil was the flat one. Obvious really. But the hard part was actually the radius. Ideally, you want the radius of all your wheels on the flat section to be the same. This is so when you change from one anvil / wheel radius to another; particularly if you have a quick release on the lower wheel tension; that the pressure on the work-piece is kept the same. I don’t have a quick release on my design, but it would be fairly nice having the adjusting wheel in roughly the same place across all wheel. After all – there must be some reason why the really old cast iron ones had a vernier on the tension wheel.
When you turn / cut the wheels, it leaves tiny grooves in the surface. Normally when you put a vernier across the wheel, it is the high points or ridges that you and measuring, but in this case it is the valleys that you are concerned with. I found these valleys could be deep and with the surface polished you could loose 0.15mm or more. The closer you get to removing the unwanted grooves, the harder and slower it becomes the remove metal. So, getting all the wheels the same diameter was somewhat slower than I’d hoped it would be.
There was another issue, when I turned the steel down to get the radius, I was left with a series of steps. These steps needed to be removed with a file before sanding. The filing process, although generally really good at removing these steps, could also leave grooves of it’s own. I found the files’ teeth regularly blocked and it was this blocking that caused the extra unwanted grooves.
When I filed the anvils down (in the lathe) and indeed sanding to a lesser extent; the all important flat section became merged into one single radius from one side of the anvil to the other. This was particularly true where the flat section was only a couple millimeters wide.
I’d used paper templates initially to check the radius. These were the same size as the anvils and apart from the fact they quickly disintegrated as soon as they got near my oily lathe. There was the issue that when shuffled, it was hard to tell them apart. The biggest problem seemed to be the resolution I could print them at. There always seemed to be steps in the printed line, which made it tricky to guess where to cut to with the scissors.
The first thing I did was cut large holes out of aluminium using an old radially scribing hole saw (probably has a better name). With the large holes, the edges were a lot cleaner and it was instantly visible which one was which. I then marked the up and cut a small section of the hole out. I could use this small section (about 10 degs) as a quick template while the anvil was in the lathe and the circular piece as a better template.
On the wheels with the tight radius, I turned them oversized and smoothed and polished the radius from one side of the anvil to the other. Only then did I cut the flat central flat. I then matched the radius between all of the wheels. If the central flat ended 0.5mm wider than intended, I figured that was better than not having a flat at all.
I made sure the cutting tip was as sharp as possible for the final cuts, and when it came to the filing stage, I went really gently, with a new 36tpi file. For sanding, I found it was better to use a wooden block to wrap the sandpaper around, as the rubber bodywork block I was using at first, was ok until the paper tore. The rubber left heavy rubber skid marks on the surface that were hard to get off without scratching the surface.
I have a DTI that I use for measurement. Sometimes to check for run-out, I place the lathe in neutral and spin the chuck with my hand. This normally has the affect of amplifying the run-out error by about 4. Even doing this, the run-out was still less than 1 thou. In other words I was as ‘chuffed’.
I’m not going to post images of me filing something in a lathe as it really isn’t something I’m proud of, or indeed would do again.
Run-out and surface in-perfections are an issue. An off-centre anvil would leave a dent in the surface every time it rotates. Therefore, getting the roller bearings on the centre-line is very important. I used a MT3 morse tapered 12mm reamer, for the central hole and a milling cutter for the bearing.
For a couple of the wheels I had to put them back into the lathe once they had been polished. The 3 jaw chuck left marks on the surface. They were far from horrendous, but I still didn’t want them. To get rid of them, took just a few seconds with 1200 grit paper and a quick buff on the polishing wheel. I don’t know if it was the right wax for the job (just what I had) but I used a cheap 500g white coloured, buffing compound, soap bar. It left the anvils incredibly shiny. Almost like chrome. The only difference being was that if you leave these, within 24 hours the shine would be almost gone. My workshop (an old cow shed) is damp, the roof leaks and there are puddles when it gets really stormy. Therefore I plan to store these anvils in absorbent towel in an old vacuum tight cake box. I am going to save those silicon crystals packets you get in the bottom of electronics boxes.
The above shot shows they are still quite shiny 2 weeks after finishing them, but the chrome like finish has long gone. You can just see that there are still some very minor scratch lines left, but the photo makes these look 100 times worse than they actually are and you definitely wouldn’t be able to feel them.
As to whether they are any good, I have a few stages to get through before I can comment. Firstly, I need to build the rest of the English Wheel, secondly I need to learn how to use it and finally I’ll need to use someone else’s to compare mine with.
With a little hindsight, it would have been better if I’d seen this guys forum entry….http://www.pirate4x4.com/forum/shop-tools/482425-show-your-hand-made-tools-8.html#post11882780
That would have made the whole thing tons and tons easier! – I’ve never seen one before and now I need one lots!
The next stage is to re-draw my English Wheel CAD drawings. I recently watched Ron Covell’s excellent tutorial video. He mentioned he is 5′ 7″ and he finds the ideal working height for him is 48″. We’re are the same height and with my current design my working height is about 6″ too low. Seeing as he is a so called ‘guru’, what he says goes. All you lofty people would find my CAD far to low and would have to mount it on blocks. Look out for the MK2 version soon.