cnc tapping Re: General Tool Life Question

--- In CAD_CAM_EDM_DRO@y..., "ballendo" <ballendo@y...> wrote:

> --- In CAD_CAM_EDM_DRO@y..., Fitch R. Williams <frwillia@m...>

wrote:

> Fitch,
>
> There are three ways to "automatically" tap in a machine.
>


> 2)Floating holders, interpolated motion

I actually class a 4th style. that is the Floating holder ,... with
release. A floating holder can tolerat both tension and compression
so that if your spindle is too slow or too fast, neither condition
will break a tap. Think of a lathe with change gears and no
synchronization between the spindle speed and the CNC controls on X
and Z axes.

If you have a programmable reverse on the spindle, you ***might***
be able to reverse it in time to prevent breakage with a floating
holder. However the speed at which you could tap would be limited by
the ability to stop the spindle and make a reversal. In order to
compensate for this many Turret lathes had a floating holder that
would release when pulled out say 1/4 inch from the holder. This
would happen when the tailstock was fed to a stop and the spindle
continued to turn. Once the tap holder was released(thus starting
the tap a-spinning), the spindle was reversed and the tap backed out
with no breakage. Since the demise of the turret lathe, there are
thousands of these floating holders with release "floating" around.
They are often too large, but I see a smaller on once in a while that
could probably be adapted to a benchtop mill. Somebody could
probably design one for a sherline(cnc or not) and make a fortune. ;-)

Best Regards,

Fred Smith
IMService