I'm pretty sure one of the usual suspects like Leigh Valley, Woodcraft, Rockler, etc. supplies a grinder component kit for folks who want to turn, carve, etc. the body for it. Can probably locate one of these kits and download the instructions for it which probably contain a good exploded diagram. Might even order one kit so you can practice the art of cloning.
I have a hand coffee grinder that is pretty simple in design, but the main frame is a heavy casting. If you think it might be helpful I could take some pictures and maybe a few measurements.
The whole thing is maybe 12 inches tall and about 5 inches across. The millings drop into a ceramic cup that is around
2 inches tall, 3 inches across and sits in the base. If you are familiar with the Cup-at-a-Time coffee brewers it is about the same overall size.
I can't find an exact picture on the web. It is similar in operation and size to this one though:
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The main frame is cast iron and open though. No nifty sliding door on top either. I cut a hole in a plastic lid for the crank and laid it over the top to keep the beans from jumping out. The degree of grind is controlled by adjusting a nut/screw above the crank. Really crude, but it seemed to work okay.
Here are a few links to some patent drawings that may give you some ideas too:
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If you follow the following link/search, you can better decide yourself just which ones would be feasible. Some of these are pretty complicated and would be hard to make from scratch.
Depending on if he wants to make the innards or the outer casing, I bet someone like Rocklers or Woodcraft sells a peppermill kit for woodturners. Not much of a stretch to change the material.
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