What is the most effective tap for threading stainless steel?

[sophiecentaur]

it is essential that you use a cutting fluid.

I have some really thick stuff which has been good to me so far.

And never turn the tap more than 1/2 turn without backing off at least 1/4 turn.

It's easy to go too far but I 'control myself' to use very small angles. OTOH, for the right material and the right tap (and the right drilling size) 'they' (manufacturers) seem to just tap in one go with continuous rotation. That can avoid the work hardening situation but you need to keep your nerve and have everything just right.

True, also I found a very easy way to get small broken taps out is by hole punching it about 20 times. It just flies right out.

A good technique and fine if you can get to the other end of the hole but the really awkward situations are often the ones that you can't get there and the hole is blind and you have to do by hand at a funny angle.
I don't have any coarse threads but that must be one way of approaching the problem.

 

[masterflo]

Let me share my little experience.
Never tapped #6x32 (M3.5x0.8 in metric system), but have used M3x0.5 in different stainless steels.

Main problem is not wear resistance, but toughness. Easy to break. Solutions:

Basic rule is great lubrication. Everybody knows, but have to remind anyway.

1. Spiral flute.
2. Interrupted thread.
3. Low friction coating.
4. HSS-PM (powder steel) - it has almost double toughness of regular high speed steel.
5. Set of taps.

I have always used HSS-PM taps. Sometimes sets (for titan), sometimes machine type with TICN coating.P.S. Removed links for example of taps, cause - OMG - I am automatically become a spammer