Over the years I have accumulated a number of "sets" as well as some more esoteric sizes that were specific to instrument jobs, some fractional, some metric. They
all are "HSS, high speed steel", I learned early on that carbon steel doesn't hold up well in heavy duty, repetitive use.
Some are (old) name brand U S made, some are chinese. They all work well enough for the
occasional uses I have now. I couldn't comment on modern steel or chineseum used in repetitive use. Most of my work these days is on my models and contraptions. Brass or aluminium mostly, not much steel.
The only thing I can say for sure is to stay away from carbon steel sets if you are working anything tougher than brass. Take a chunk of 2X4 and drill a row of holes on the edge. Whenever possible, spend the money for good quality, U S made HSS individual taps as they are needed. It will pay off in the long run. Cost more, a lot more, but it's spread out over time so it isn't
that painful. Taps are not too bad, it's the dies that cause my gut to clench up. And yes, the
adjustable dies are worth the extra cost.
Further, I would look at smaller sizes, Nrs 12 ,10, 8, 6, as well. And/or metric equivs. Nr 6-32 and 8-32 are very common in electrical fittings. I have down to Nr 3/0, 000-120, but those are specific to my models and have very little real world use beyond optics. There is little use for stuff larger than 1/2", rare except for pipe sizes. 3/8, 1/2, and 3/4 pipe sizes are quite handy for electrical and plumbing.
One last shot: The world is going metric, fast. So, unless you are working on something old or specificly fractional (like old cars or fence fittings) I would try to build a set of metric sizes first.
Bill Hudson
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Keep your eyes open on the lower listings .