Power Tapping

[Toolmaker51]

I like normal tapping heads for drill presses, as few have reversing spindle, or too much inertia for a 'smooth' deceleration and reverse. The little Hardinge TT [including all the similar de-clutch drivers] don't need a torque arm [tommy bar] and are 1/3 or 1/4 overall length of ETTCO, Tapmatic etc. Can tap blind using depth stop by adding the .100 for the body to disengage pin driven collet holder. Cascao, homeengineer, Paul Jones..., can't recall who, made one DIY. A threaded body compresses a decent valve or die spring, threaded body adjusts the drive torque. [Excellent student project!] Also productive on lathes...engine, chuckers, turrets.
They all disengage while tap is down hole and feed lever is lifted. While body spins, tap is static. Can wait all day to reverse spindle.
Only 'drawback' is when many holes are encountered, via normal tapping head, increase RPM to back out tap. Serious time saving, easier on taps also, with proper coolant in play.