01-25-2015, 07:41 PM
(01-25-2015, 05:34 PM)PixMan Wrote: We have a winner!
Yup, I went with a Ø 0.332" (Letter Q) drill. I did have a GH3 class tap to use, though not my preference in style as it was a high quality HSS 4-flute hand tap.
I used to beat on engineers for putting tap drill size on a print at all. Just give the thread you want and let the machinist determine the right tools to do it with. I sent an e-mail back to the engineer who sent me the print, pointing out that if you actually use the drill specified, your resulting thread does NOT meet the spec for a Class 3 thread with the minor diameter being too large.
I guess I'm just a sloppy machinist but 7 thou oversize tap drill for a 3/8-24 thread wouldn't make a lick of difference for any application I might have.
I must agree however that "engineer's" specs need to be scrutinized.
Steve
Busy Bee 12-36 lathe, Busy Bee Mill drill, Busy Bee 4x6 bandsaw, Homemade 9x17 bandsaw, Ad infinitum.