I'm in the market for a specialty tap size, for threading bicycle bottom brackets, like this expensive tool:
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Is there any technical reason this thing should cost $500, or is it just a case of a small market?
Since I have a lathe, mill, and rotary table, it got me to wondering whether I could make one of my own and after machining, heat treat it for hardness. Do I have a prayer of getting a working tool by going that route, or does this type of thing require grinding with specialized equipment (that I don't have)?
They have a good picture of the cutting surfaces in these pictures:
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more pictures are on this page:
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This looks different than the smaller taps I'm familiar with. I've never tried making a tap, but I get the idea from this cutting surface profile that each cutting tooth advances just a bit, sort of like moving in the compound feed on a lathe when cutting threads. In that case I guess it would be tapered, even beyond the initial starting taper. This would be one of the more complicated parts I have tried making. I have never cut tapered threads for example.
Thanks,
Dave