The BST Mini Tapper

When I embarked on the Miser Sterling engine project I came to the sudden realization that there would be a lot of tapping and drilling for 0-80 hardware.  After obtaining some of the taps, one look had me saying, "I'm gonna bust a bunch of those bastards"

I have a hand tapper, the ubiquitous Asian import, but this is so large there will be no "feel" on a tiny tap.

Enter the Mini Tapper:

The head of the frame has been bushed with a brass liner, the shaft is a ground SS rod.  The base has a matrix of 5/16 threaded holes for fixture or clamping of the part.

I powder coated the frame in my standard shop color, Columbia Coatings Teal.  Of all the powders I have used in my powder coating work, Columbia seems to be the best.  My #2 favorite is Caswell Plating's Super Wet Black, it looks like "black glass".

I used an ER11 Collet adapter as the "chuck".  A few people in the Valley Metal group questioned the holding power but I routinely use this on 10-32 threading operations all the time and the tap turns without run out and has never slipped.

Knob Upgrade

2/28/2026

I have a Snap-On hex bit driver that I like to use for hand tapping.  I had made a drive adapter for the Mini Tapper so I could have powered tapping.  The adapter is a 9/16 hex socket adapter with a 1/2-13 nut epoxied into place.  This threads in place of the knob.  Using this required changing the knob for the adapter with turns out is a PITA.  I designed and 3D printed a knob that presses over the adapter.  I pressed this in place and now can turn by hand or powered without having to mess around changing parts.