06-01-2014, 08:15 AM
That's kinda funny - I was just thinking someone read it wrong, really wanted a 4-40 thread... Years ago I made a larger tap with square corners in the flutes. Worked fine but dulled fast, heat treated with a propane torch. Final sharpening with the corner of a grinding wheel may have helped.
I seem to recall saying to myself, "the next time put the taper on after the threading". Probably something to do with my tired old lathe and the pitch varying slightly under the increasing load caused by the taper. Might have been my imagination, the quest for perfection and all that. I put the flutes on after threading, the leadscrew backlash left no question in my mind about it..
I seem to recall saying to myself, "the next time put the taper on after the threading". Probably something to do with my tired old lathe and the pitch varying slightly under the increasing load caused by the taper. Might have been my imagination, the quest for perfection and all that. I put the flutes on after threading, the leadscrew backlash left no question in my mind about it..