Harold,

Collets shouldn't be used much beyond a thou or two past nominal for
starters, and many of the tap drill sizes are not fractional----so you'd
find not many of the sizes you'd desire can be so held.

Thanks for the heads up on that one. A crazy idea: turn the shanks so
they fit? I do not have a lathe, but will probably eventually get a
small one.


The other problem,
albeit it a minor one, is that drill shanks are often quite badly badgered
from slipping---which could complicate getting them in a collet.

Unless it happens routinely in/from the collets, I could always buy
replacements for any pose a problem.


I
highly recommend a good hand tightening drill chuck (something like an
Albrecht), half inch capacity. They're fast and precise. If you think
you'd want to change drills on the fly, you could even entertain buying a
Wahlstrom. Big bucks, and sort of dangerous in the half inch size, though.
The 3/8" capacity Wahlstrom is a sweet dream.

I have a 1/2 in Jacobs that seems excellent to me. I'm confident that I
will use it many times, but since it adds roughly 4 inches to the
spindle, it would be nice to be able to avoid it when feasible; again,
the enemies are the difference in bit/mill position, and the clearance
for a change. I do not expect to eliminate head movement and
registration problems, but I am willing to throw a little money at
things that will help make them rare events.

Bill