According to Allen :
wrote:
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.
Minimum bore size will be limited by the bearing OD, of
course, and for smaller holes there are proper roller-burnishing tools
available. They cost plenty, and only fit given sizes.

Dan

Thanks for the tip

I can visualize you forcing the bearings into the hole and the outer race of the
bearings picking up the same RPM from the hole as the two meet. So the relative
positions of the bearing race and the hole remain constant throughout the push
and withdrawal. Now, if my understanding of what you are doing is correct,
then is there any particular advantage drawn from having the chuck rotating?
The operation appears not unlike swaging a barrel.

The impression that I got was that the OD of the bearing was
smaller than the ID of the bore, so it rolled around the bore as the
workpiece rotated. (The "some pressure" would be pressure of the roller
against the side wall of the bore, not axial pressure. Thus, it became
a form of roller burnishing tool. Not as stiff as one with three
rollers pressing into the bore at 120 degree spacing, but for a soft
workpiece material, it should suffice.

Enjoy,
DoN.

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