Thread Engagement
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Re: Thread Engagement
Re: Thread Engagement -- jswinder	Post Reply	Top of thread	Forum

Posted by: kelly_bramble ® 11/28/2005, 16:50:09 Author Profile Mail author Edit

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
Re: Thread Engagement -- jswinder	Post Reply	Top of thread	Forum

Posted by: jswinder ® 11/28/2005, 16:38:40 Author Profile Mail author Edit

Thanks Jack

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Re: Thread Engagement
Re: Thread Engagement -- jswinder	Post Reply	Top of thread	Forum

Posted by: Jack Anderson ® 11/28/2005, 16:32:56 Author Profile Mail author Edit

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
Re: Thread Engagement -- jswinder	Post Reply	Top of thread	Forum

Posted by: B.Hughes ® 05/04/2005, 10:48:40 Author Profile Mail author Edit

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
Re: Thread Engagement -- jswinder	Post Reply	Top of thread	Forum

Posted by: randykimball ® 04/27/2005, 19:33:30 Author Profile Mail author Edit

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

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Re: Thread Engagement
Re: Re: Thread Engagement -- randykimball	Post Reply	Top of thread	Forum

Posted by: jswinder ® 04/28/2005, 08:11:28 Author Profile Mail author Edit

Thanks for your help.

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Re: Thread Engagement
Re: Re: Thread Engagement -- jswinder	Post Reply	Top of thread	Forum

Posted by: jswinder ® 05/04/2005, 10:51:59 Author Profile Mail author Edit

Thanks B Hughes for the Help.

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