As the hole is tapped, the tap has to move forward into the hole. If the work is held in the lathe chuck, and the tap is held rigidly in a chuck in the tail stock, what's gonna move?
They make a nice tap-holder (see MSC) that's got a hole in the backside that slides on a 1/4-inch rod. Chuck the rod in the tail-stock chuck, rest an arm of the tap-holder on the tool rest, and urn on the lathe REAL SLOW. Dave Golber
The TS slides on the ways. I don't cinch it down.
Peter
Do you mean that as the tap advances, it pulls the TS along?
In that case, it could be part of the problem. The combination of that tension and the tapping torque might release the arbor. Try feeding it very gently with the TS hand wheel. A little pressure instead of tension might make a difference.
Bob
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