John has decided that Chalupy acres has a tutelary god. That's the good news. The bad news is that his name is Sisyphus. He was the one that kept rolling the stone up the hill, only to have it roll over him before he got to the top. In this matter of gear-cutting old Si has been right up to scratch. OK, so far we have made a dividing plate. We even have a blank gear at hand. The big moment has arrived. We must make a cutter to the correct profile.
Now the subject of gear profiles is somewhat controversial and quite mathematical. But I propose to avoid this as much as possible, although the practical details are really not that complicated. I am trying to cut clock gears. These are "cycloidal" profile gears but you can ignore that. Thing is you have to do is shape a cutter to the correct profile. You can work out that profile. The tip of the tooth is curved. And so I went through a bunch of calculations and came up with a radius of curvature for which I happened to have a diamond tool. And behold, Sisyphus came in for a visit. I proposed to cut the cuttter with the same setup used to cut the gear; i.e my DSO (Dremel-Shaped Object) in the vertical slide on the lathe. My carefully chosen cutter would'nt stay put in the DSO! The shank was defective. The shanks are 6.3 mm which I suppose is some fraction of an inch in RGU, but the shank was 5.95 mm and the DSO collet wouldn't grab. Curses!
Now, Houston, we have a cutter. Next step is to set up the divider. We must make sure the teeth of the gear are uniformly spaced. So the divider plate comes into action.
Next we use our previously made arbor (read "axle") and bolt our gear blank into it.
I am very pleased. The whole lashup -- the DSO held to the vertical slide, the homemade divider plate, the primitive index pin -- it all worked. The cutter was all wrong for reasons given. But all the things I was worried about -- wobble, for instance -- did not materialize. Maybe brass would have failed, but since I am planning on plastic gears, this will not matter.