Ok, I guess UPS must have come back and made a second delivery on Friday. I
found the Foredom 25 hand piece sitting in the drop box in front of my
office on Saturday evening. Not sure why I unlocked it and checked...

Now I need to make some mounts for it. The HF hand pieces are about .85
diameter. The 44T is about .95, and the 25 is about 1.026 I could just
mill out the HF clamps, but I may want to use the HF handpieces again some
time, so I guess its time to design a clamp for the Foredom 25 and see how
it performs. I want to make some improvements to my clamp design anyway.

For a baseline or comparison, the one HF handpiece has about 100 hours of
run time on it. The last 40 hours was almost continuous nonstop. It is
just now starting to develop some noticeable side play. By grabbing a bit
chucked up in it I can wiggle it slightly and feel it. I'm guessing its
under .01 according to my calibrated finger, but I can feel it. I stopped
the mill at 7.5 hours into the job to check clearance and that no steps were
being lost. Then it ran 32 hours straight. I stopped it very briefly
because the snap in connection was rattling. All I did was snap it back in
and it was good. That was probably my own fault. I had backed off the
amount of protrusion of the drive shaft to match the Foredom tool spec, and
when I went back to the HF hand piece I had not put it back the way it came.
I had just assumed the Foredom spec was generically correct for all hand
pieces.

I have to say that the HF tool is really not bad. I bought two of them as
some of you might know. I had a brush carbon up and quit working right at
about 30 hours on one motor. I swapped it for one of the new brushes that
came with the tool and all was good. The other has over 100 hours of
runtime at maximum speed continuous duty and its still working fine. The
hand piece with 100 + hours is starting to show some slop or side play. For
a very occasional user who takes care of their tools they might last their
lifetime. Very likely if they only use it as a foot pedal controlled hand
held tool. For a commercial shop I suspect downtime for service would
override cost savings, but I have not run a Foredom hand piece or motor that
hard yet. Even a jewelry shop would probably take months to put that much
hard use on their motors.