jim rozen wrote:
In article .com,
says...

I used to manufacture an aluminum valve that had a polished
bore. I mounted a small permanently-lubricated ball-bearing assembly
(sealed both sides) on a stiff rod and clamped that in the lathe
turret, and clamped the valve body in the chuck. Spun the body and
fed the bearing slowly into the bore using power feed and some
pressure, and got a usable surface. I got the best finish when I had
ground the bearing's outer race to a barrel shape, and polished that.

How much undersized from the bearing OD did you leave the
bore to start?

Jim

On a related subject I was making a cross slide stop for my Southbend lathe
http://www.rupert.net/~solar/SOUTHBEND13.html.
The materials at hand where a salvaged chunk of cast iron (broken Record
vice) and some string trimmer shafting.
BTW - string trimmer shafting is high quality, precision machined carbon
steel more or less equal to drill rod - NEVER THROW IT OUT and if you come
accross some - grab it.
I wanted a hole (actually two) drilled in the cast iron that would give a
sliding, no shake fit for the shafting.
I forget which number drill gave the loose fit but the next smaller size was
a somewhat too tight fit - light press?
I drilled the smaller size and then used a length of the shafting in this
manner.
I chucked it in the lathe and applied a vibrating engraver to the rotating
shaft.
Then I chucked the (now modified with vibrator warts) shaft in my drill
press and jammed that through the undersized hole in the cast iron - rerady
for disaster that never came.
The result was a *perfect fit*. Pushing the shaft through the hole felt like
pushing against a well tuned dashpot (and still does after several years of
use).

A buddy, and my maching guru came by later that day for a rum and coke
session.
I dragged him down to the shop to show off my latest triumph.
As soon as I said "no shake" he got that "total BS" look in his eye and
grabbed the protuding shaft.
Try as he might he could not detect *any* play!
This guy had forgotten more about machining than I will *ever* learn.
Essentially, I guess, I sort of 'burnished' that hole.

Regards.
Ken.