CHAMFERING FORM THREADS

[LancoUSA]

We just started to use form taps here on aluminum and steel parts. I am having a hard time getting a good chamfer. Is there a Trick to getting a good chamfer on the thread after it is tapped with out going back over them all with a spot or countersink? We spot with a 90 degree heavy, then drill then tap.

 

Thanks

[jeff]

Why chamfer after it's tapped?

You're making more work for yourself.

If your tap is kicking up that big of a burr to where it's altering the chamfer, then either you have too small of a tapdrill size,or the tap is dull... most likely.

[chris m]

Drill, countersink, tap; run a 65% tap drill and you should have minimal problems. As you said, always csink heavy with a form tap to prevent bulging.

 

C

[LancoUSA]

Thanks guys. I have adjusted my countersinks a bit heavier. It is helping.

[Tim Johnson]

I drill, countersink Ø.030 larger than the tap dia with a center drill, tap. The 60° chamfer works better with the displaced material.