Thread Question

[mcrump28210]

I have a bore that measures 0.870 and I am going to thread 20 TPI. I have to machine a matching shaft and will fit as I go. My question is, what does the OD of the shaft need to be turned to prior to threading. Thanks!

 

[Conrad Hoffman]

I'm thinkin' a 0.922" x 20 thread is what you want. So shaft 0.922" or a tad under. But I've been wrong before- just ask my wife. Check with another thread program to be sure. BTW, inventing new thread sizes is to be avoided when possible.

 

[Kyle Smith]

I'm thinkin' a 0.922" x 20 thread is what you want. So shaft 0.922" or a tad under. But I've been wrong before- just ask my wife. Check with another thread program to be sure. BTW, inventing new thread sizes is to be avoided when possible.

That sounds good to me. Ø0.870" + 1/20 = Ø0.920", closest fraction is 59/64 = 0.922".

If you can open the bore to Ø0.888" you can make the male 15/16"-20 UNEF, slightly more common. Bore Ø for class 2B is 0.883"-0.895".

 

[mcrump28210]

That sounds good to me. Ø0.870" + 1/20 = Ø0.920", closest fraction is 59/64 = 0.922".

If you can open the bore to Ø0.888" you can make the male 15/16"-20 UNEF, slightly more common. Bore Ø for class 2B is 0.883"-0.895".

Thanks guys. Custom firearms stuff so it's a bastard size.