On 12/9/2020 6:06 AM, Jim Wilkins wrote:
"Snag"Â* wrote in message ...

Â* On my bench-top mill , well it ain't busted no more ! Today I
replaced the speed control pot and reassembled it , installed it and
it's working fine now . Since I was on a roll , i decided to set up the
rotary table and engrave the dial for the X axis that I lost (original
wouldn't work with the PF) when I installed the power feed . This
machine uses 8 pitch leadscrews ... which means 125 divisions , which
requires a 25 (or multiple) hole index plate with my 90:1 worm ratio .
And I don't have one but I do have the time and material to make one !
Actually I'm making a 50 hole plate , got it machined to size and
mounted in the rotary table and almost ready to drill . I figger it's
best to bolt the RT down before I start ...

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How?

I've read of several possible ways to generate and test an index plate
or similar geometric pattern but I've only tried two, and found them
difficult without a DRO.

The messiest was graduating a crossfeed dial for an AA/Sears lathe with
a 5/16-24TPI LH thread. That's 41.67 lines per turn.

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That dial must have been a trip , how on earth did you resolve the
partial space ?

I used the rotary table to drill the 50 hole plate I needed to scribe
125 lines on the dial ... On my 90:1 RT , I moved 1 5/9 rotations per
hole - 1 full turn and 20 holes on a 36 hole plate IIRC . The dial was
36 holes on the 50 hole plate ... and what's cool is that now I know how
to do this , I can reproduce any hole pattern I need .
--
Snag
Illegitimi non
carborundum