Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Things I've learned from doing many now - what works for me.

Lathe 400rpm
Use lots of WD40 and a toothbrush to keep clearing away the chips
Very critical is to have the tap centered perfectly in the middle (spend some time eyeballing this) if there's any chatter whatsoever the tap is either trying ride up or down
Don't put too much pressure on the tap, its not needed and just keep going in a couple of thou at a time. When you're at the depth you want, let the piece rotate at least another 4x for a really clean cut