Hello Ethan, Internal splines, which is basically what that extrusion die would be are much harder to do than cutting gear teeth on the OD of a gear blank. The internal splines would have to be done on a slotter ( or possibly a shaper with the right set up, i.e. some cutting machine with a linear reciprocating cutting motion ) or cut into the die with EDM or wire EDM processes. Much more difficult, and therefore more expensive manufacturing processes. Original gears probably were shot in a plastic injection mold, but the mold making is very expensive too, and not something to do for very small production runs. Too bad you couldn't find someone with a broach, because broaching internal splines might not be as expensive a manufacturing process as long as you found someone with the broach already made up. To have a tool and die maker have to make a broach would also be expensive. Also extrusion die blank material would have too not be too hard to broach. But then you have to have the extrusion process set up and run. All in all, if you can't find them already made up, milling the teeth into blanks or slotting on a lathe are probably going to be your only really feasible options. Best Regards At 08:13 AM 4/22/03 -0700, you wrote:

There are 3 ways that instantly spring to mind for making this gear, using the sort of tools you'd find in a good amateur workshop (i.e. no CNC tools). 1) Mill it a tooth at a time on a dividing head. The disadvantage is that this is slow. The advantage is that the equipment needed is not too exotic. The pitch sounds simmilar to small watch or clock pinions, so a tooth cutter for those might be able to be used (but be warned such cutters are _very_ expensive). 2) Cut it on a hobbing machine. Once set up, it'll just cut the gear -- you don't have to index the blank round and feed it past the cutter by hand. The problem is that hobbing machines are not common (although not impossible to make either). Where you get a suitable fine pitch hob is another matter... 3) Injection mould it. David Gingery has written a book about making a small injection moulding machine which I think would be suitable for making these gears 1 or 2 at a time. The problem is making the mould. The obvious way to make something of that size would be by EDM. The electrode could be made by one of first 2 methods (you'd only ever have to make one of them :-)). EDM is not impossible in the home workshop, or so I am told... Methods (1) and (2) have the advantage you could make the gear in brass, which would easily outlast the owner of the plotter :-) -tony