I tend to use spiral flute taps these days, they push it up out the hole

No problem on steel, it comes out much like you get when drilling

For through holes you can use a spiral point tap as they will push the swarf ahead of them.

In both cases you don’t wind the tap backwards to break the swarf, just keep turning.

25psi air line?

I know forming taps need bigger holes than cutting taps, but do they not also need more torque?

Having to exert more torque than necessary when tapping is an evil for the hobby machinist, which is why I’m increasingly keen on serial taps for threads M10 or above.

Thread forming taps can readily work well in malleable materials like aluminium, less easy in harder or prone to work hardening metals. The potential problem is that there is nowhere for excess material to go, and so achieving an exact hole size for threading may be critical to full thread form without the risk of tap breakage. On the other hand, threading a boss, or near the edge allows external deformation to adjust the thread to be the correct size.

In practice in commercial manufacture with hard materials, it is usual to find there is a double thread peak on the inner diameter (due to an intentional oversize hole), and in fact this is perfectly satisfactory even if the thread profile is thereby out of tolerance.

As a final step you can drop a little “worm” of plasticine down the hole and run in a second or bottoming tap.

plpus one for that set up John and the magic 25psi