On Fri, Dec 16, 2011 at 8:48 AM, Brooke Clarke <bro...@pacific.net> wrote: > Hi Don: > > Sure converting lengths is easy and I have metric, English and weird taps > and dies, but how do you turn metric threads?
How would you cut 40 tpi or 24 tpi? You put in the "correct" gears to drive the lead screw so the tool moves at the desired rate To cut metric threads they use a gear with the correct ratio to drive the lead screw. Yes if the lead screw is 1/8 inch the drive gears will have some odd ratio but it works. The reason it works is because back in 1959 they re-defined the inch to be an EXACTLY 25.4mm. From then on gears with integer number of teeth will do the metric/imperial conversion perfectly. I think I said a while back that any machine shop that can't figure this out has likely already gone out of business. Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.