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Stephen B.[_4_]

wrote:
On Monday, March 20, 2017 at 3:44:35 PM UTC-4, Bob La Londe wrote:
"Bob Engelhardt" wrote in message
news
I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were. Now,
the question is: where are they better used than cutting taps? Since they
are more particular about the hole size, I won't use them unless they have
some advantage.

Thanks,
Bob

I wonder how forming taps would work in punched holes to maximize the amount
of thread created.

In interviews with many tap manufacturers, I've always heard them emphasize the importance of hole accuracy for thread-forming taps. It sounds unlikely that punching holes would be a reliable way to do it.

We have progressive dies at work that use them. The main advantage there
are no chips to deal with.
The punches are sized per tap requirements. This means we get less
engagement at the bottom (in the punch blowout). The bolts are not under
high stress so we are not worried about striping out.

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