Ken Sterling (Ken Sterling) wrote in message
...
Something doesn't sound right....how thick is the plate? Won't the pilot
be
unguided on the other side of the plate? Make a guide block and clamp on
or
tack weld it. Or even a nut.

Tom,
This is just a hypothetical situation ... I was wondering if such a
thing existed as a piloted tap - just to get a tap started "dead on"
at the beginning of the process (by hand) where the pilot part of the
tap would keep you lined up until you were cutting the thread straight
and the pilot would indeed "work through the plate" but then you
wouldn't actually need it after the tap was started straight. I have
never seen such a tap, and didn't know if anyone had ever tried it or
not - my feeble grey matter just seemed to think it may be a good idea
in certain situations.
Ken.

In my estimation, it wouldn't be a good idea. One of the problems with
tapping holes is the discharge of the chips. A pilot would, for the most
part, minimize, if not eliminate, the area needed for chip accumulation and
cutting geometry. Even worse would be when the hole was not sized
properly, nor drilled straight. A tapping block would most likely serve
far better.

Harold