On Sep 2, 5:46 pm, "Terry Coombs" wrote:
....
I plan on turning multi-tooth cutters (think shaped rings with teeth cut
into them) for the two DP's used on my lathe . The centered cutter cuts to
depth with straight sides , the cutters to either side of it shape the
flanks of the adjacent teeth .

Think "hob". I never made one because Boston Gear sells gears I could
bore out to fix my South Bend lathe. Hint: don't jam a screwdriver
into the gear train to lock it if the chuck is too tight. @#$%^ trade-
school kids.

A straight hob such as you described can cut perfect gears if you roll
the gear across it, the problem is to synchronize them.

I think the easier method uses a spiral tooth hob, like a worm gear,
but the blank is tilted so the hob cuts straight across it. The hob
turns the blank and automatically cuts the proper involute curve on
the teeth as they roll through the cutting edges. Descriptions of
hobbing on a horizontal milling machine suggest gearing the hob
spindle to the rotary index if possible. Rough the spaces out first.

The gotcha is threading the hob at the correct circular pitch to match
the existing gear.

I like the idea of
using an existing gear as an index , but am concerned about my ability to do
it accurately.

Me too. Before finding the 52 tooth gear the plan was to make a 13
hole ring for the rotary table.

I have made a flycutter , 12 deg angle at the bottom (back side of the bit
on CL , using AL4 brazed 1/4 by1/4 cutters) that works well , and my first
attempt at indexable end mills works , but I believe really needs
coolant/lube to work really well .

Lube yes, coolant no. I use it if the machine has it but at home just
brush on a little cutting or pipe threading oil. Speed is 80 - 100
FPM, less with home-made cutters that could break or fly off.

Jim Wilkins