306 SS threading

I'm making some shifter and brake pegs for a friend's bike , and have run into a small problem . I suspect I have work hardened the SS when I drilled it , because I've never had this much trouble cutting threads . I have units made and drilled 3/16" diameter and about 1 1/2" deep , but need some advice . The threads are to be 3/8-16 , and only need to be about

1 inch deep . The first one I drilled like 2 inches deep , in 2 steps (after a 3/16" pilot hole). The piece was quite warm when I finished . Should I take these out to the tap drill diameter in 1 step ? Should I use coolant , and if so what kind ? The pegs are slotted 1/8" slots spaced 1/8" apart (done with a parting tool) , and got very warm during this machining , could that have hardened the SS some ?
Reply to
Snag
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Take the work hardened skin off with carbide tooling at a very low speed (for something around 3/8 diameter 200 RPM) . Drill your holes at slow speed and make big chips ( aggressive feed) use plenty of cooling/cutting oil, don't let the work heat up.

cheers T.Alan

Reply to
T.Alan Kraus

Get a NEW tap to tap the holes. 300 series SS can be a pig to tap with "pre-enjoyed" threading taps of dubious ancestry and questionable history! :-)

Wolfgang

Reply to
wfhabicher

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