Paul in OKC
Member
Well, with all the talk of the triple start thread buy lately I decided it was time to play. Having more time than money, and access to my work machines, I made a three start tap and die. 'Tap' is from a piece of drill rod, die is from some heat treated 4140 scrap. Both heated red hot and dropped in oil. Size is 1/2" by 8 tpi, triple lead basically 24 threads per inch. Advances 1/8" per full rotation. Practice material is basic plastic for the die threads piece, and what I believe is hard rubber from one of my bowling ball experiments. This the second attempt. First one the tap worked well, the die was split and as it was tight I expanded it and snapped it in two. No question about hardness! Anyway a fun experiment. Now to get after the pen! I took a gamble on my sizing and did not split this one, although I drilled and tapped it and will use a small cut off wheel if I need to. But first shot is a good fit.
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