On 2011-01-31, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Ignoramus4844 fired this volley in
:

It was not exactly straight, as I expected. But then I put the
toolholder into the spindle, spun it, and trued it as it was mounted,
which, not surprisingly, gave an excellent result.


OK... I'm with you on most of it, but I must assume it was a backing
plate-mounted chuck; no? yes?

Yes, backplate mounted.


Tell me about the truing process. I have only ever mounted one backing
plate chuck (on a lathe, not a flippy little spindle adaptor), and it
took me most of a day to get it within a half-thou.

And I still don't understand how one would take up mere tenths of conical
variance when shims and such aren't available thinner than about 0.001".

In my case (the usual, I assume), I trued the plate to the lathe first,
assuming the chuck would bottom-out conically at least as true as the
spindle run-out. Then I only trued to center, not conical alignment.

I guess I could true the "boss" on the mill the same way, but I'm
wondering how you went about it. And, how to ensure the bolting-down
doesn't creep with excessive loading.

I did the boss on the mill to, the whole works, taking off only a
minute amount of material.

i