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Custom ACME threads on an old Craven grinding machine???

assface421

Aluminum
Joined
May 18, 2016
Need to make a Nut for an acme thread on this old CRAVEN grinding machine we have in the shop. I went over to measure the thread, The major diameter is 1.900. I used an Acme pitch gauge and it fits a 29° 4N perfectly. So I went and looked up the thread on a chart and can not find it. The closest is 1.75 or 2.0 major diameters. What's going on? is this a weird thread or custom? Needed some advice on how to proceed.
 
sounds like a 2 incher to me since the major is 1.964....its worn maybe....see if there is a spot that looks newer and mic over that to see if its closer than the 1.9...also mic the nut at the runout end to see if they made it smaller on purpose way back in 1927...back then on the nut you turned a spot before threads to the major minor diameter so that when ya tool scraped that you was there and that was ya thread guage....LOL

PS....maybe the manual and specs are here
Craven Brothers - Graces Guide



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It's 1.900 the whole length of this 3 foot lead screw. the minor diameter is about 1.636 (measured with calipers to get a reference). That's what is leading me to believe it's a custom or non standard thread. If it were meant to be a 2 inch thread, the thread would be tall as shit. Measuring the nut wouldn't do any good, It is worn. I was tasked with making a new threaded sleeve for the nut.
 
So it's a 1.9'' dia thread - where's your problem, ......just because it's a ''non preferred diameter,'' doesn't mean much, .that's why we have machine shops.

Ignore the ''odd'' diameter and just work to the formula for that thread pitch, and everything will fall in to place.
 
It's 1.900 the whole length of this 3 foot lead screw. the minor diameter is about 1.636 (measured with calipers to get a reference). That's what is leading me to believe it's a custom or non standard thr wasead. If it were meant to be a 2 inch thread, the thread would be tall as shit. Measuring the nut wouldn't do any good, It is worn. I was tasked with making a new threaded sleeve for the nut.

When you look at the threads on the screw do they look short for a two inch acme thread? The reason I ask is there is a stub acme thread. Before I did my first post I looked up sub acme threads. In my cursory search I only found stub acme that had common dimensions. Doesn't mean there aren't others.
 








 
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