Determining thread dimensions?

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sspbass
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Determining thread dimensions?

Post by sspbass » Thu Sep 18, 2014 11:52 pm

I've got one chance left to make the proper threads otherwise i need to buy another tube so I'm imploring your help.
I'm using an Bridgeport EZ-Path II CNC lathe and with its threading dialogue I basically just need to know the major and minor thread diameters and the thread pitch. I'm not a machinist and I'm not familiar with creating custom threads.
My only limiting factor is the tube is 1.5" OD 1.37" ID.

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RPM509
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Re: Determining thread dimensions?

Post by RPM509 » Fri Sep 19, 2014 8:07 am

I don't have one handy, but I am positive the answer you are looking for is in the Machinist Handbook.
It has all the threads, pitches, major and minors, angles etc for all of them.
"a butt tuba" - Palindrome

Historian
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Re: Determining thread dimensions?

Post by Historian » Fri Sep 19, 2014 9:40 am

RPM509 wrote:I don't have one handy, but I am positive the answer you are looking for is in the Machinist Handbook.
It has all the threads, pitches, major and minors, angles etc for all of them.

+1

A must have if for no other reason than to possess the cumulated knowledge
and metrics painstakingly gathered over the centuries for metal mastery. Plus
fun to randomly peruse.

wp6529
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Re: Determining thread dimensions?

Post by wp6529 » Fri Sep 19, 2014 9:41 am

Machinery's Handbook is the expensive but difinitive reference for damned near everything.

There are tons of references for thread charts on the 'net though such as:

http://en.wikipedia.org/wiki/Unified_Thread_Standard
or
http://www.engineersedge.com/screw_threads_chart.htm

It's nice to stick to a standard thread, i.e. UN, UNF, UNEF if you can find one suitable rather than doing a totally custom thread.

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curtistactical
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Re: Determining thread dimensions?

Post by curtistactical » Fri Sep 19, 2014 10:03 pm

I agree on the machinist handbook its a must have but here are a few tips. If take the major diameter minus the pitch it equals the minor diameter. If you are making both mating parts you can pretty much make the thread whatever you want. No matter what the diameter is the thread depth is the same for any given pitch, example would be a 1/4"-28 thread has the same thread depth as a 1"-28 because the pitch is the same. For your tube threads use somewhere between a 24 and 32 thread pitch. For your given tube size I would use a 1.437-28 thread. Hope this helped some.
Joseph Jones
Curtis Tactical
07/02

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