Here is another piece to the puzzle. I made a spring loaded tap guide for the mill. I started with a length of 3/8" 0.028 wall tubing and a spring that seemed right from the local home supply store. I pressed a 0.7" length of brass into one end of the tube and reamed a 1/4" hole though. The plunger was machined from drill rod (silver steel) because it was handy. The parts are below:

The cap was supposed to press on to capture the spring but I had to resort to Loctite though as it was a little loose.

It has about 1" of travel. To use it is placed in a tool holder and put on the spindle. A tap wrench is held between the hole to be tapped and the guide. The spring puts slight pressure on the tap but mainly keeps the tap straight to the hole.

It works well, especially for a mill with CNC Z axis.