By Don Wiederhold
When you can’t get a full turn on your tap handle when tapping on the lathe, try this trick.
Put your lathe spindle in neutral, so it spins freely. Run your live center into the end of the tap and lock the tailstock in place. Then, position the apron so it supports the force of the tap handle.
Using a wrench, turn your lathe chuck while simultaneously feeding your live center inwards.
If depth of thread is a concern, set your tailstock reading at zero, and you will be able to see the exact distance you are tapping to.
Seen in the photo is my 3/4-16 tap. Remember to tighten your lathe chuck securely, as high forces are reached when tapping with a tap of this size.
In addition to setting the spindle to neutral, it’s a good idea to make sure the lathe is disconnected from power so there are no unpleasant surprises.