Problem- Roll threading 2-56 look issue

[nfs7713]

We are thread rolling an alum extrusion 2-56 (kinda gummy characteristics) 6063 maybe not real sure.

Question 1: Does any one have any info on how the threads are supposed to look?

The recomended size is .078-.080. we went with .0765 roughly. the threads still look like they have 2 crests, top and bottom.


Question 2: Is this typical for thread roller taps?



Any info on this matter would be greatly appreciated. nfs

[Delw]

The threads will look like threads with out burrs.
I get a reccomended drill size of 5/64 or .0781, your .0015 smaller and in all honestly that may make a difference in a 2-56. but I doubt it.

Its not typical as what you describe.

does the hole your drilling have a nice finish? if the finish looks bad in the drilled hole then so will the thread on the minor.
are you sure you have the proper lead programmed in (feed rate) if your off on a small thread like this it will make a huge difference.

Delw


sticky material on small threads make sure you use good strong coolant

[little bubba]

The 2 crests would indicate an oversize hole and the thread isn't completely forming.

Double check your hole size, the actual size of the hole made, not the drill.

[nfs7713]

Thanks for the help, this mat'l is real gummy, we went with a .075 drill and the threads look better now. thanks for the help. we also slowed the feed down on the drill from 10. ipm to 5 ipm seemed to help stabilize the hole size.(side note: tried .074 drill in 6061 then tap and tap broke immediately