I need to cut a 30tpi thread for an Enfield receiver.
What gear train do I need to set up on my chinese 12x36 in. lathe?
Present set up has a 40 tooth drive gear, 80 tooth idler driving a 40 tooth gear on the lead screw. This set up lets me cut 28 tpi at the C-8 position and 32 tpi at D-1.
I used to be able to do this but my old 80 year old mind has failed me today.
jclayton

quote:

Originally posted by jclayton:
I need to cut a 30tpi thread for an Enfield receiver.

What Enfield action uses 30TPI?

quote:

Originally posted by malm:

quote:

Originally posted by jclayton:
I need to cut a 30tpi thread for an Enfield receiver.

What Enfield action uses 30TPI?

The action (trigger guard screws) on Enfield’s are 1.4â€x 30tpi.

I don't have a metric pitch guage, but, by measuring an Enfield screw, I came up with a .83mm pitch.

Well, the lathe chart shows a setup for .8mm and .875mm pitch.

Both use a 46 tooth drive gear, any idler, and 60 tooth bottom gear.

Then, C6 will get you a .8 mm pitch and C5 will get you a .875 mm pitch

I hope this helps, Rojelio

It’s probably a little cheaper and quicker to just buy some new screws.You can buy used or brand new Enfield guard screws from several different suppliers.

quote:

Originally posted by Rick 0311:

quote:

Originally posted by malm:

quote:

Originally posted by jclayton:
I need to cut a 30tpi thread for an Enfield receiver.

What Enfield action uses 30TPI?

The action (trigger guard screws) on Enfield’s are 1.4â€x 30tpi.

Yeah, that makes sense. I wasn't thinking trigger guard screws... Thanks Rick!

Thanks for the help!! I should have been able to do this conversion. .875mm should be close to perfect.
Yes, it would be easier to order screws, but here in the Canadian boondocks life is not that simple.Postage and customs fees are about $20 on any shipment from the USA.
And I would rather build my own.
Thanks again.
jclayton