k.pearson wrote:

On Wed, 21 Dec 2005 12:05:17 -0800, Eric R Snow
wrote:



On Wed, 21 Dec 2005 12:37:13 -0500, k.pearson
wrote:



On Wed, 21 Dec 2005 16:02:55 GMT, "Dick" wrote:


snip


Greetings Karl,
The D mount chuck should contact both the taper AND the back face.
Often times the chuck, faceplate, etc. will have been bored oversize
so that only the back face of the chuck contacts the back face of the
spindle. The chuck should fit such that it requires a little tap to
jar it loose. On the spindle of the lathe there should be two lines at
90 degrees to each other extending radially from the cam tightening
hole. When the camlock is tightened there is a line on the cam that
should fall between the two lines on the spindle. Everything else you
have said about chips, dents, bumps, etc. is absolutely true.
ERS




Thanks Eric. I knew someone would set me straight. I hadn't heard of
anyone boring a chuck (!) Ugh - bad vibes there. And I'd forgotten
about the lines for the cams - been a few years since I've retired and
I am working from memory.


You may want to use some Hi-Spot dye to find out where the chuck is
touching the spindle face. If it is in two spots roughly 180 degrees apart,
the chuck is pretty clearly warped. Assuming it is a 2-part chuck, you
may be able to face it carefully, after removing the pins, or just
replace the
backing plate with a brand new one. You can also use the dye to check
contact between the spindle taper and backplate taper. Many collet chucks
have adjusting screws similar to the Buck Adjust-Tru scheme on 3-jaw
chucks. The backplate mounts to the spindle, the chuck mounts with some
slop to the backplate, and the screws position it radially to dial it in to
perfect center. If you have such a chuck, mount the backplate by it self,
make sure you can mount it repeatably, ignore whether it is perfectly
aligned, and then face the part of the backplate the chuck mounts to.
Then, align the chuck for perfect radial alignment.

Jon