Confusion Of Style Of Taps To Purchase

That kind of like the roughing and finishing taps of an Acme, Bill?

I've done a hack job of hand grinding a UN tap when doing tough materials like Inconel or Monel in such a way that the peaks of the form are truncated, but still have a back relief. If I get about 50% of the thread height, then a factory grind has a much easier time of it. Plus it's a use for dull taps.
 
I know about those for Acme Tony. The ones "Joe in Oz" spoke of cannot be found here for some odd reason. I PM'd him to get the manufacturers name. These taps would make Inconel or Stellite much easier to handle.

"Billy G"
 
I've never seen them sold here either. Sure would be nice with some materials.
 
QUESTION --- How the heck can something like this exist in other countries and we here in the US can't get them? It makes no sense.

"Billy G"
 
I have ground off the point on taps since it was for the sharpening new taps. That gave me a little more thread depth. I have heard of plug taps but for pipe threads. Never used one for production. I usually would grab a SHCS that was as long as the hole was to be threaded to test the actual depth. I would use a depth micrometer or dial caliper to check the length the screw's thread.
 
Those look about like the ones I was hand grinding. Never knew they were factory anywhere. I wonder if they are available in UN.

Bill, I think we're talking about two things. You're talking about length of usable thread (or depth in a hole) and we are talking about the thread height, the difference between major and minor diameters. If you grind the OD of a tap, you aren't cutting to full height and the load is much less, plus the tap is a lot stronger because the "tips" are wider and not sharp points, or minimal flats.
 
I bet someone with tool grinder could alter a set of taps to do that.
 
I am talking about the same thing. Not wording it correctly. As you see from the link those tape are progressive in diameter or thread height.

"Billy G"
 
Bill has it right, they are a 3 pass system. Adom Booth showed using a set a while ago on YouTube. One makes a roughing pass, the next cleans out more material, and the final one takes a light finishing cut.
 
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