Jon Elson wrote:
Bill Schwab wrote:

This should help:

http://www.practicalmachinist.com/vb...d.php?p=856062


It did! When they refer to indicating "the cone," is that inside the
chuck "below" the jaws? Correct me if I am wrong, but that seems to
be overkill with a 3-jaw chuck??

I'm not an expert on D1-anything, but I do have a Sheldon lathe with
D1-6 and several chucks, backplates, etc. for it. The chuck (or back
plate) has both a face and a taper that are BOTH supposed to seat to
the spindle face. The taper of the chuck is a "female" taper that
seats on a very short male taper on the spindle. You need the tapers
to mate closely to get repeatable mounting of the chuck. You might
check these with blue spotting dye. You probably don't need to
actually lock the cams to get an impression on the tapers. I'd put
the dye on the chuck, because the male taper of the spindle will be
easier to inspect.
Of course, you should get even transfer of the dye all around the
spindle. You can also apply dye to the face of the chuck and see how
well that seats against the spindle face. Again, it should fit
relatively well, rather than at just a few points.

You said something about indicating the rough surface of the chuck
ID. If thre is no ground taper on the back ID of the chuck or
backplate, then I really don't think it can be called a D1 mount. It
fits the machine's spindle, but it can't be mounted repeatably. I
can't imagine using such a contraption.

I bought a cheap D1-4 mount and it had a turned taper instead of ground,
for what I was using it for it was fine as great accuracy was not
required. I will be wary of that supplier in future though and have
bought more expensive, not by a great amount, D1-4 mounts which have
ground location taper and face, I would buy those for anything accurate.
The cheap one also had one of the camlock pin locking screw holes
mis-drilled, re-drilled, and a thread insert to correct it.

My Phase-II knockoff of the Buck Adjust-Tru chuck will grip any size
round with less than .001" runout. (Yes, I bought it new, on sale,
and it was a fine investment!) I took the backplate off a wrecked
real Buck chuck that came with the lathe.

D1 mounts usually have an orientation mark, where one pin is marked to
line up with one of the cams. usually there is an extra straight line
by that one cam.

If the external taper on the spindle is not true, then you really have
a problem. If it is true, and the dye indicates the backplate is
fitting well to the face and taper, than mount the backplatew without
the chuck and face it until it completely cleans up the front of the
backplate. Then try remounting the chuck and see if it is better.

As for camlock torque, I just use the usual chuck wrench and make it
snug. I tighen them all up a little at a time, maybe going around the
spindle 3 times.

Jon