On Sun, 06 Apr 2008 20:17:26 +0700, Bruce in Bangkok
wrote:


Is anyone doing metal polishing (I'm interested in Stainless) and
could give me some advice.

Fortunately I don't do this anymore - it's tedious, dirty work - but I
built SS marine hardware for a living back in the early 80s. This is
the general procedure I used.

1. A 50 or 60 grit fiber back disc and/or a belt sander with rubber
contact wheel to remove pits on pickled hot rolled stock and to radius
welds and sharp edges. The "blue-grit" lubricated discs and belts seem
to be worth the extra cost. You can skip this step if you're dealing
with cold finished bars or sheet.

2. A sequence of 80, 120, 180, 240 cloth backed 5 inch PSA discs on a
DA pad adapted to a disc grinder. A relatively low speed, less than
5000 RPM, grinder is best. You could probably get away with higher
RPMs, but disc life will be short. They really aren't meant for even
5000 RPM. The adapter is just a piece of round stock tapped on one end
for the grinder and the other for the pad.

3. Scotch-Brite or Beartex fine SiC light deburring wheel, e.g.,
8S-fine. 8 x 1 inch is a convenient size for a small buffer.

4. The hardest buff you can get and SS buffing compound. I used to get
buffs made to order from treated cotton with 1/4 inch spiral sewing.
The treatment made them stiffer; not so important when stacked up on
the buffer, more so when buffing offhand with just one section. Use
lots of pressure and rake the wheel when it gets glazed. Again, 8"
wheels are probably the right size for a 3/4 HP buffer.

While not necessary, a bigger buffer can speed things up. 3 HP is none
too large; I had a 10 HP and could hear it slow down when working on
large pieces.

--
Ned Simmons