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 assist 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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