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wrote:

A fair bit back, Jim Rozen described a drill press for Printed Circuit
Boards that sounded like a good design. A microscope with a cross hair
to align the board, and a drill that comes up from the other side to
drill the hole.

Dust? Drilling PCBs makes lots of abrasive dust that will get into your
bottom motor spindle bearings. If the board is already etched, you don't
need a microscope or cross hairs to align the drill bit in the center of
the pads. The lack of copper in the middle of the pad will center the
bit automatically if the operator can get it reasonably close. And if
you need better accuracy than that, then CNC is the way to go (it
doesn't need the microscope or cross hairs either).

[...]

So now I more or less have a collet. I will have to buy a slitting saw
to put a slit in it, but the hole is tight enough to hold a PCB drill
now. Can't see any run out. I think that part will work.

Dan

Aren't there 1/8" collets in most Dremel-type motors? Making a collet
from scratch sounds like reinventing the wheel. Carbide PCB drills #60
and below like to run at 25K RPM -- your home brew collet had better be
pretty accurate in run out if you expect the bits to last longer than
about three holes.