On 2008-09-30, Jim Wilkins wrote:

Drill bits are probably good to a thousandth. Dowel pins are cheap and
very accurate.

Agreed.

The better Jacobs chucks are worth it on a milling machine, probably
not on a cheap drill press. Twist drills are flexible anyway and
center themselves on the punch mark, so runout in the chuck doesn't
matter all that much.

Well ... that depends. Yes, a typical half-inch Jacobs chuck
can't *directly* hold a drill bit much below 1/16th of an inch, and
0.007" runout is probably tolerable with a 1/16" drill bit. However, if
you are using one of the sensitive drill adaptors, and a #70 or #80
drill bit, your runout is going to be on the order of the drill
diameter, and that is likely to break the drill bit once it gets deep
enough into the workpiece. Even more so if you are using solid carbide
bits for drilling printed circuit boards. They are very brittle when
exposed to side loads.

The one Enco keyless chuck I have is pretty good, too, although it's
on the tailstock of my lathe where I can't quickly measure the runout.
For small holes they are handier than keyed chucks, for larger ones
they have a problem with slipping.

Hmm ... a real Albrecht is good at self tightening, so it tends
not so slip.

A good chuck isn't really wasted on the drill press, you can move it
to a better machine later.

Agreed -- and if the drill press and the lathe tailstock have
the same Morse taper (or the lathe tailstock is larger so you can use
an adaptor sleeve), you can move the same chuck back and forth at need.
(Granted, it is nicer to have them each have its own good chuck. My
lathe currently has a Polish clone of the Albrecht in the 5/8" size, my
drill press has a Jacobs (close of the Albrecht, though looks a little
different), and my little Compact-5/CNC lathe has three chucks -- a 1/8"
Albrecht, a 1/4" Albrecht, and a 3/8" Rohm, which is a good clone of the
Albrecht.

A worn Albrecht with a large bit can self-tighten to the point
where you need a strap wrench to loosen it.

Enjoy,
DoN.

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