Jim Wilkins wrote:
On Sep 2, 9:10 am, woodworker88 wrote:

What you need to do is run the rotary table in vertical mode with the
tailstock, with the gear on an arbor in between centers.

Be sure the cutter forces the gear toward the larger end of the arbor.
If you use a live center and driving dog remove *all* play from the
dog.

Depending on
the tool, you'll be running either a commercial multi-tooth form tool
in a slitting saw arbor, or a single point tool in a flycutter/boring
bar holder (which you'll probably have to make yourself).

You can make the holder from a large bolt. Center-drill both ends,
turn the shank to fit a collet, then cut a slot across the head for
the bit and add clamping setscrews. A larger, fine-thread tap like
10-32 or 1/4-28 is less likely to break. Try to put the bit's cutting
edge radial so it will be easier to shape and regrind. The Grade 5
bolts I've used turned easily to a very good finish.

Set the cutter on centerline vertically,

Center it on the tailstock point, for instance.

set your depth of cut with your y-
axis dial, and use your x (longitudinal) feed to cut each tooth.
You'll probably need to take more than one pass, going all the way
around the gear each time.

You can cut one tooth slot almost to full depth for a short distance
to mark the tooth outline, then rough all the teeth out almost to that
outline with a Woodruff cutter. You have to feed a one-tooth gear
cutter slowly, especially on the finish pass to avoid rotation marks.

I needed a splined shaft to press into a motorcycle sprocket, with 13
teeth which my rotary table can't do, so I took a 52 tooth change gear
for the AA lathe, made an indexing stop to fit between the teeth, and
put it on the same shaft as the gear blank. I cut the slots slightly
undersized and pressed the sprocket on, and the thin chips the
sprocket shaved off looked even all around.

If you have a similar gear to copy, make a fixture that fits the
gear's center hole and guides the bit radially into a tooth groove.
Use it to fit the bit so no light shows between the bit and a tooth.
The one I made was an aluminum bar with a hole for the shaft on one
end and a 1/4" slot for the HSS bit on the other, milled at the same
table Y position to make the slot radial. The bit slides in the slot
with minimal side play.

You could soot the bit in a candle flame to find the contact spots you
need to grind down. I couldn't get bluing to work well enough on
smooth HSS. Mark the center of the bit so you can align it with the
tailstock point.

I used the unfinished bit for roughing the slots, alternately taking a
pass around the blank and grinding the bit to fit a little better.
That way it was always sharp. It was hard to grind both the tooth
curve and the back relief properly with a Dremel, so I gave it
excessive relief and it dulled quickly.

This description is a mix of two jobs, trapezoidal splines for the
motorcycle sprocket and involute splines for a hydraulic gear pump.
Both were press fits that carried several horsepower.

Jim Wilkins

That's what I love about this place . Creative minds willing to share
their ideas . My appreciation to both of you , both have given me more food
for thought .
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 . To do this I will need the table vertical ,
the gear blank on an arbor , supported by a tailstock . I like the idea of
using an existing gear as an index , but am concerned about my ability to do
it accurately . I will be using an arbor that has a 3/4 shank and a 1" dia
with a key slot on the cutter end .
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 .
--
Snag
'90 Ultra "Strider"
'39 WLDD "Popcycle"
Buncha cars and a truck