ABTOMAT said:
I would never, ever buy a cheap no-name tap set. You're just asking for one to break or dull out in the middle of a job on Saturday night. The metal that goes into those things is like McDonalds secret sauce.
That is the absolute truth!
Take it from someone who taps LOTS of small holes in tough material: if you want taps that are prone to breakage and difficult to use, buy one of their sets. If you don't, buy them separately so that you can choose the right characteristics.
What do I recommend? First, buy only HSS (high speed steel) taps - not "carbon steel", which are much more brittle and prone to breaking in a hole (this is a bad thing.) Carbon taps also wear rapidly; when I'm tapping steel, I can feel a carbon tap start to dull within just a few uses. As the tap dulls, the amount of force necessary to cut threads increases dramatically, which means that the risk of breakage skyrockets.
Second: Buy 2-flute taps, which are much stronger than the typical 4-flute variety, especially in the smaller sizes.
Third: if you are going to tap through holes (in other words, a hole that goes clear through a piece, as opposed to a blind hole that ends inside the item) buy spiral point taps. (These are NOT the same as spiral flute taps!) The spiral point taps shoot the chips out in front of the tap, making the typical "half turn forward, quarter turn back" routine to clear chips unnecessary. With a spiral point tap, cutting threads is about as fast and easy as screwing in lightbulb.
Fifth: Buy quality taps, but you don't have to overspend. I've found that Cleveland, Greenfield, and OSG are all good quality products; of them, Greenfield is my favorite. You can often find some or all of these on sale at the better tooling suppliers (Enco, J&L, Rutland, MSC.) J&L, in particular, runs a 25% or 35% off all taps promotion every couple of months, always on a Thursday or Friday.
Finally, make sure you have quality tap wrenches that hold the tap securely and squarely. As in many things, Starrett is the "gold standard", though the tap makers usually make top-quality wrenches as well.
Oh, and one last thing: a good cutting oil is a must!
Hope this helps!
-=[ Grant ]=-