Precisionworks you say you use mostly thread forming taps, while I understand most of what they offer and the premise behind how they work vs cutting taps, I'm curious what applications would make a forming tap a better option than a standard tap? Also what kind of force and alignment is required? Do you need some type of drill/mill press or can they be hand started and hand turned?
I realize the results are cleaner and chip free, but what normal work would require that?
Well, in large production quantities, tapping a cross-hole through the wall of a tube, there's actually substantial cost savings from simply not having to clear tap chips from the inside of the tube. But the main benefits there were speed (2-3x the spindle speed of a cut tap) and tap life (rather longer, even at the higher speeds).
They're
really good for blind holes -- particularly when there's a tight limit on the depth (to avoid breaking through, or maintain a minimum thickness for strength) and the threads must be more than 2 diameters or so deep (which makes spiral-flute taps more challenging to use).
Also, the threads they leave are stronger than cut threads, so there's some application where short threads are necessary, but not strong enough, such as thin-wall tubing or sheet-metal. You can get good threads down to 2 threads thickness, at least.
The material matters, of course; they work great in aluminum, soft steel (even
really low-carbon steels like 1005 that can be unpleasantly gummy with cut taps), and can be ok in brass. You wouldn't want to try them on cast iron.
WRT forces, they usually need about twice the torque of a cut tap, IIRC. They can be used by hand, but the higher forces translate into higher risk of breaking the tap without an alignment jig of some sort. They'll pick up their own lateral alignment like a cut tap, but (also like a cut tap) they'll easily start angularly misaligned if you're not using a fixture of some sort, and they are likely to break if you go very deep with an angular misalignment.
