06 Feb, 2011
Cutting the Gear Cutter!
Posted by: Raynerd In: Webster Engine
I`ve made a start on the gears. I`m using John Stevensons informative article on spur gear cutting, using his calculations along with Ivan Laws book – Gears and Gear Cutting from the workshop practice series. I`ve made the buttons and holder hardened them.
With this made I cut a piece of large silver steel to turn into the gear cutter blank.
Here is the intended blank of silver steel to made into the cutter:
I then parted off the 0.125″ wide cutter I needed after centre drilling for fitting onto the arbour. Yes, you hear correctly – [u][b]I parted!![/b][/u] – look at the new tool! Although delighted with it, more comments will come later in the week.
Now I often hear people say, “a mill is just a lathe on its side” – obviously in a loose sense. Since I have a DRO on my mill I didn`t and still don`t see why I couldn`t place the cutter form tool in my vice and hold the blank in the er32 collect chuck. That way I can use the DRO on my vice to feed the profiling tool 0.092″ into the cutter blank as required. All looked to be going well, the cutter tool the edge of the silver steel blank:
Then it seemed to stop cutting, yet it was still moving into the profiling tool. I had to stop and see what was wrong and then I found that the silver steel cutter blank was cutting the buttons!!
Fine – I made a wrong call and clearly the buttons were not silver steel as I presumed they were (they had gone hard, a file slid off them). So today I managed to get some 0.275″ silver steel from my engineering pal down the road which is as near to damn it the 0.274″ button dia I need. I heated them cherry red and quenched. I decided to move over to the lathe so it was easy to centre and it wasn`t likely to run too fast so I put it on fairly slow speed. I re-ground my cutters and made sure they were sharp. It cut very well, although one side cut better than the other which was a bit annoying, but it did cut. I ended up with this:
I`m going off from John Stevensons gear cutter plans now a little and I`m just using a single point cutter. It is unlikely I`ll use it again and to be honest, I`m cutting ally so it shouldn`t take too much of a bashing. I`m making ally gears, I know that it really is not suited but consider this will run a few times each year at maximum when it is built, I can`t foresee too many problems.
So I cut the disk in half and bored it square to the face, hardened and tempered. Needs a final grind now and sharepen but that is as far as I got:
Now this picture concerns me a little – I think it is the angle that I`ve presented it to the camera but the cutter looks a little bent. It doesn`t look like this in real life so I`m hoping it is an optical illusion. I`m posting the picture anyway, it shows a rough profile of the cutter:
So next job is to finally cut a gear!