According to Norm Dresner :

[ ... ]

Don

I had to drill a hole yesterday and was using a #75 drill. Using my
7-diopter OptiVisor I could see no wiggling of the end of the drill which
should be an indication that the runout is pretty small. I've finally
gotten a dial indicator and magnetic base and I intend to measure the runout
as soon as I can get to it. Since the chuck does in fact close to (pretty
close to) zero and if the runout is as small as I think it is, I'd probably
be a fool to replace anything even though I'd love some more modern
conveniences.

That I find amazing. What brand of 1/2" drill chuck is it which
closes down to grip a #75 drill bit?.

Can you check whether it will grip a #80?

If it does not, you can go for the sensitive adaptor (either the
one in the eBay auction to which I pointed, or another similar one)
which will also give you more control and feel in feeding the drill bit.

I've done down to #70 in the tailstock of my small lathe -- an
Emco-Maier Compact-5/CNC, with a 0-1/8th Albrecht chuck on a #1 MT
arbor. And that worked well enough in 12L14 steel -- but I kept
worrying about the lack of feel that the leadscrew gave me with that
tiny a drill bit, so I was *very* careful.

Good Luck,
DoN.

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