3/4"-5 ACME Thread

3/4"-5 ACME Thread
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Posted by: schase ^®

09/22/2005, 20:22:59

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I have been surching for information on the thread profile of 3/4"-5 ACME Thread and I can not find it I looked in the machineries handbook and on the web, and I could not find it. I only found 3/4"-6 and on manufactures websites they give some information but not all. I found nominal Diameter, root diameter pitch and the included angle but I can not find the dimension of the width of the crest or the root. I would appreciate any help I am sure this should not be that hard of a problem.

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Re: 3/4"-5 ACME Thread

Re: 3/4"-5 ACME Thread -- schase Post Reply Top of thread Forum

Posted by: lbmakem ^®

09/24/2005, 12:51:33

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hope the following will help:
pitch= 1/tpi
Major dia=nominal dia
pitch dia= major - (pitch*.5)
minor dia= major - pitch
addendum= pitch*.25
tooth thickness= pitch*.5
lead= pitch*number of starts
depth= pitch*.5
helix= pitch dia*3.14159/lead (this is the cotangent of the angle)
to calculate the width of the crest or root you need the pcd & minor dia allowances for the required fit.
The minor dia tolerance's are:
For 10 threads per inch and coarser (minus .020")
For finer threads per inch (minus .010")
The pcd allowances are as follows where 'A' =sqrt of the nominal dia:
2G fit= A*.008
3G fit= A*.006
4G fit= A*.004
5G fit= no allowance
The width of the flat at the root of the thread=
(.3707*pitch)- (.259*(minor allowance-pcd allowance))
The flat at the crest of the thread=
.3707*pitch-(.259*pcd allowance)

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Re: 3/4"-5 ACME Thread

Re: 3/4"-5 ACME Thread -- schase Post Reply Top of thread Forum

Posted by: randykimball ^®
Barney
09/22/2005, 23:16:54

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Try any 5 pitch ACME thread for the width of and thread profile. All sizes will be the same. Then compare any 5 pitch ACME to the nominal size and do the same for the 3/4"-5 as the one you find at some other diameter, except change it proportionally to the new one. For example: On a 1"-5 ACME the pitch diameter is .9 and the minor diameter is .8... so, on your 3/4" thread (external) your pitch diameter is .65 and your minor diameter is .55..... major diameter is .75",... pitch is (of coarse) .200.
When I was younger I cut many an ACME 3/4"-5 on an old #5 WS with a Landis Die-Head... you have brought back many memories.
Mine were on valve spade stems.
-randy-

The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.

Modified by randykimball at Thu, Sep 22, 2005, 23:18:22

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