F. George McDuffee wrote:
snip

Looks like I need to source some 1.375 round stock in leaded
steel. What alloy do I need to specify? This is a quick-change gear, so
doesn't need to be high-strength. I suspect a brass gear would do the job.

It will be a major project to machine a steel gear. Because of
the low speeds/loading on the change gears we have found that
aluminium work fine [we sued some 6061 T6 we happened to have]
also the mechanical grade of micarta or formica makes good gears.
This was a common timing gear material.

That's good to know. I have some 6061 It would make it much easier,
plus this gear would make a better "fuse" if it were AL.

Drimel tool or 1/8 air grinder will be very helpful in hand
grinding the involute profile into a single point cutter. Unless
you like grinding use the smallest piece of tool steel you can.
3/16 is plenty for 1.0 module. You will need to grind the top of
the tool down to center of the holder or grind in hook to avoid
negative rake.

I have some 3/16 cobalt steel stock which I'll probably use.


Thanks for the input