Hy guys!
I'm new here, and i'm in touch with you asking for some help!
I've to machine a lot of 1/4-20unc threads, and i'm having a lot of problems to.
I'm using a 5,2mm solid carbide to do the hole, and using a 1/4-20unc HSS-E tap to do the thread, with 9 Meters per Minute speed, floating tapper. But the tap is enlarging the hole and recutting the thread. I've made a lot of tests, but I couldn't discover why it's happening. Can somebody help me??
Thanks a lot!