Carl Boyd wrote:
"Michael Gray" wrote in message
news
I have a Cummins 7x12 minilathe and a nicely hand-ground Acme profile tool
I made. Right, so I have to cut a worm at 6.4 tpi. the change gears
with my 16 tpi leadscrew will be:

(30/50) x (40/60)

Can SKS tell me how to set this up so the gears actually mesh? Do I have
to somehow interpose an idler in there somewhere?

Help!
Mike in BC


Generally speaking you need to couple the 50 and the 40 together so they
rotate in unison. Not sure how you do that on a mini lathe. A 24 and a 60 in
the gear train give you the same ratio ( but I see from the grizzly web page
that that the 7x12 does/may not have a 24 tooth gear).

Carl Boyd


If the gears do not have keys to lock them together with, degrease
them and stick a couple drops of superglue between them and press them
together. It'll pop apart with some persuasion from a sharp edge driven
between them, and acetone will clean the residue off.

Or you can just shoot a hole through them with a drill and tap it, and
drop a screw through, if you don't want to trust the superglue to hold up.

If you have to resort to idlers, use 2. First idler will change the
direction of feed, second to get it back into the direction it needs to
go. If there is not a leadscrew reverse on the lathe.

Cheers
Trevor Jones