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Blending external threads

Question asked by robert dattilo on Nov 23, 2015


     I have a 3/4 -32 RH 3B thread with 5.76 revolutions. This is not a cosmetic thread but we'll actually be molding this into a part

I'm wondering for those who do alot of threads, what portion of a revolution is typical to blend the internal thread out to come back out to the tap drill dia. At present I'm trying leaving the full pitch diameter upthrough the 5.0 revolutions. Then I wind down to the tap drill with the last .76 revolution. Is that

reasonable or or should it go quicker, like start the wind down at 5.5 instead of 5.0. Because it's functional & not cosmetic I'd like it to be more typical.


Thanks in advance for any input.

Rob_D SW 2015_Sp4.Thread example.jpg