i agree with g taco, most threadless steerers are not thick enough to cut threads into. also if you have a 1 1/8" steerer you could have a dilemma since every quill stem i have seen is for 1 in steerers. if you do have a one inch steerer, it would be much better to just buy a threaded fork and headset. tap and die sets aren't cheap, they are easy to use if you know what you are doing, but to find one with a one inch die would cost you.