Spiral point cut taps were our first tap choice.

There were M0's programmed so the operator could blow out coolant and apply oil to the counter sunk holes.

Spiral pointed taps, on the other hand, are not even closely related since they produce an effect quite the opposite from spiral flutes. Not long ago we had a large-ish 304 stainless job Using this same reasoning, you should rarely - if ever - use spiral flutes of any kind in materials with fine or powdery chips, i.e. You do not need a good cutting oil (sulfurized or fatty) to form tap successfully I've been waiting for years for a job that will let me load the cost of a set onto it. Beats the pants off hank bushes, rivet nuts and so on. One really impressive type for thickish sheet metal work doesn't even need a starter hole! Pop it in the drill press, run at a good speed, lean on the work whilst it goes red hot so the tap pushes the metal out to form a hollow boss on the back and follows through to form a thread. Some types need a pitch matched feed for best results, usually high speed beasts for CNC machines. You invariably need significant end force to get them moving and keep the thread forming so attempting hand use tends to be a bit dispiriting although there are some, usually smaller types, that will work by hand. Some are quite specific as to what materials they can be used with and what speeds they can be run at to work well.

There are differences between makes and types for good reason. Best to check with the guys who made them.

Form tap vs cut tap