Thread Engagement Smile
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Posted by: jswinder

04/27/2005, 16:40:16

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I need some info on thread engagement. When tapping a hole the thread engagemnet is based on the tap drill size. I need to understand where the engagement is taking place. Can any body help. Thanks,






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Re: Thread Engagement
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Posted by: kelly_bramble

11/28/2005, 16:50:09

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Your question is a little confusing. When designing for a minimum thread engagement, the general industry practice is 1.5 diameters of threads to engage on assembly.

When tapping a hole, there are standard pre-tapped hole sizes which are drilled to accommodate the tapping tool.







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Re: Thread Engagement
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Posted by: jswinder

11/28/2005, 16:38:40

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Thanks Jack






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Re: Thread Engagement Yell
Re: Thread Engagement -- jswinder Post Reply Top of thread Forum
Posted by: Jack Anderson

11/28/2005, 16:32:56

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Dear Threader,
I was told in school, that you need at least the diameter of tap, in length of thread engagement. Example: If you were taping a 3/8-16 thread hole. You would need at least 3/8 of an inch in threads minumin. 3/8= .375 .375 * 16 = 6 Minumin of 6 thread. Engagement: one revolution = one thread engagement

(*) = Times sign X







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Re: Thread Engagement Smile
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Posted by: B.Hughes

05/04/2005, 10:48:40

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Some general Thread information...The larger the tap drill size, the smaller the percentage of thread engagement. The Machinery's Handbook can help with thread engagement questions.

Two thread strength dependents are (1) percentage of thread engagement, and (2) length of thread engagement.

Rule of thumb engineering designs use 75% thread engagement, and a length of engagement of 1.5 times the diameter of the screw.

Quite often in high speed machining facilities, the progammer or operator will use the largest tap drill allowed which will result in the threads meeting the specification (Machinery's Handbook and/or in-house drawing). This is done to help reduce tap breakage and to increase production.

According to the Machinery's Handbook, there is minimal decrease in thread strength when utilizing 65% thread engagement versus 75% thread engagement.

I would suggest reviewing the Machinery's Handbook regarding this subject, as well as discussing with a tap manufacturer, and of course, discussing with those who will be performing the work.

I hope that this information proves helpful for you. Good luck.







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Re: Thread Engagement
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Posted by: randykimball
Barney
04/27/2005, 19:33:30

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It SHOULD engage at the pitch diameter. + according to the quality and style of the thread.

-randy-




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Re: Thread Engagement Smile
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Posted by: jswinder

04/28/2005, 08:11:28

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Thanks for your help.






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Re: Thread Engagement Smile
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Posted by: jswinder

05/04/2005, 10:51:59

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Thanks B Hughes for the Help.






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