Gearing a hand-operated knob that moves a valve will probably
work with aluminum gears, but the change gears in the lathe can
transmit considerable torque on coarse threads. If they don't
break off, they are going to wear really fast.

All the more reason to try it first with aluminum, then,
to get a feel for it before making a "real" set. I'm not
likely to make power feed cuts at the capacity of the
machine anytime soon, at least not knowingly. I'm hoping
that when nicer weather rolls around, I'll have found
"real" gears anyway, so I'm hoping this isn't a permanent
solution.

Someone else suggested 12L14, which also sounds eminently
sensible... maybe I can get it and the drill blank at the
same time.

--Glenn Lyford