snip
BTW, in watchmaking/clockmaking we make fly cutters in the lathe out of
round stock. Since we use hand gravers (ala wood turning), we turn the end
of the rod to a profile that is an exact fit between two good teeth of the
wheel we are replacing. File the profile to the center line, harden and
temper. Grind relief on the tip and polish. Takes about 30 minutes.
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Sounds like a good idea. Cutter will automatically be centered
and both sides will be symmetrical. Does the tool have enough
strength for anything beyond sheet brass? What is the working
radius of the tool? Do you just have a flat on the tool to
orient in the holder or is there some special technique?

Do you use soft drill rod / silver steel and harden or grind
round hard tool steel? We are limited to a propane torch and a
bucket of water for hardening (but if the old timers could do it
… )

GmcD