Acme or not?

[Stephen FollowsParticipant @stephenfollows82099]

I’m restoring an old vice. The screw looks like an Acme in all respects. Problem is I can’t find it in tables. It’s 7tpi x 0.54 inch diameter.

Tables go from 6 tpi to 8 tpi, no 7.

I need to make a new spindle and have no idea what change gears to use on the lathe. Anyone come across this thread before? It’s Swiss made BTW.

[Stephen FollowsParticipant @stephenfollows82099]

Odd thhread

[not done it yetParticipant @notdoneityet]

Are you sure it is not metric? Swiss made, so likely?

[JasonBModerator @jasonb]

Diameter falls within TR14 max/min but pitch is between the usual 3 or 4 mm

[DC31kParticipant @dc31k]

If it is Swiss, is there a possiblity it could be metric, trapezoidal form? The dimensions are not so far off 14 x 3.5mm pitch.

How are you measuring the pitch? If you measure over 21 threads, do you get exactly 3 inches?

You would have to tell us what lathe it is in order for us to advise on gears.

[not done it yetParticipant @notdoneityet]

Posted by JasonB on 26/04/2022 19:02:53:

Diameter falls within TR14 max/min but pitch is between the usual 3 or 4 mm

Yes, 3.5mm near as dammit isto swearing.🙂

[Michael GilliganParticipant @michaelgilligan61133]

Rumour [or at least a discussion on hobby-machinist] has it that the Kurt D60 screw is 7tpi stub ACME

**LINK**

https://www.hobby-machinist.com/threads/harden-kurt-vise-screw-threads.24385/

MichaelG.

[Author]

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