On Oct 1, 7:29*pm, "Michael Koblic" wrote:
"DoN. Nichols" wrote in message
On 2008-10-01, Michael Koblic wrote:
big snip

But you probably don't really need to do this. *Just learn to
live with your 3-jaw chuck, or get a 4-jaw and learn to set it properly
when (and only when) you need the accuracy.

Thank you Don and Jim.

In my case it is more about understanding the concepts than about immediate
practical application. I am getting a better grasp.

One final question: Grinding - does it damage a chuck or is it mainly the
ways and the bed you have to be careful about? I was thinking it was almost
inevitable for the grinding dust to get inside the chuck and causing
mischief there. *I am talking about grinding things clamped in the chuck
rather than doing the chuck itself as Don suggested.
Michael Koblic,

Opinions vary on lathe grinding. The dealer I bought mine from warned
never to grind on it because it has hardened ways. I haven't need to
anyway because I bought new chucks for it and have another small lathe
that is easily disassembled for thorough cleaning, plus a surface
grinder with a tool grinding swivel table. The small lathe and the
surface grinder each cost less than a new chuck.

Ground shafting is easy to find cheap or surplus if you can adapt to
whatever diameter you find. Old dot-matrix printers have some and you
can salvage it from hydraulic cylinders or car shock absorbers. In my
experience hydraulic cylinder rods are good steel that turns and
threads well once the chrome has been removed with a carbide bit.

If you need to improve on a lathe-turned finish you can lap it with
fine loose abrasive like Clover compound in a home-made cast lead lap.
This doesn't spread abrasive grit all over like dry grinding with a
high speed wheel.

I've been able to finish bearing surfaces to a few ten-thousandths and
a near mirror polish with fine single-cut files and black SiC
sandpaper, using the tool marks as a guide to file evenly.

Jim Wilkins