Lotsa good info here. One of my own- I use a drawbar on the tailstock from the carriage. set the feed speed to whatever pitch thread i'm doing. gun taps in tailstock chuck, low speed, lotsa sulphured oil cut 20% I use a old chuch that is well worn. Save my good one for closer stuff
Some good advice here and even I learned a couple things here. Don't know if it's mentioned here but always remember to oil the ways of the lathe to help glide the tailstock towards the headstock during powertapping. I would also not use a plug (or bottoming) tap for the initial powertapping. Use a 4-flute taper end tap (or spiral) for the initial threads and if they are not deep enough, then finish off the threads with a bottoming tap in a vice or something. I've always liked to be pulling back on the tailstocks' chuck when backing out the tapped hole with my hand to ***ist pulling that tap away from the hole and messing up the first lead thread.
Brand name does matter. I will not buy a tap unless it is from OSG, Greenfield, Balax, Guhring, Hertel, or Kennametal. Those brands aren't a lot more expensive than the off brand or no-name stuff, but their products are head and shoulders more durable and closer to spec. Pictures Thread cutting spiral flute tap (1/2"-20): http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2009117&PMT4NO=0 Thread forming tap (#10-32): http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=7760578&PMT4NO=0 Notice that the last one has no flutes? No chips are made, so no flutes are needed to evacuate them.
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