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


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