I recently bought a used Tapmatic 30X on Ebay, and I finally got it rigged up on my mill-drill this evening. Holy crap is this great! I can tap a 4-40 hole in about 3 seconds. Perfect, no fuss-no muss-no bother. The alignment of the tap to the hole doesn't even have to be exact, the Tapmatic self aligns. It used to take several minutes per hole, and I always feared breaking a tap. Hand taps are a thing of the past for me!