Hello Jon;

Yes, I'm familiar with that technique; I use the paper on a glass plate
to lap the surfaces of woodworking plane irons and chisels, etc.

In the case of these aluminum parts, I'm trying to find some way to
power the process and speed it up significantly. These are custom
hardware parts for guitars and basses, so it's not a high tolerance
flatness issue, they just need to look good under plating. Right now,
almost 2/3 of the labor of making the part is in polishing the flat
surfaces. There's got to be a better way tucked away in pro polishing
shops!

I'm wondering whether it's better to do the sanding in a linear form,
as in a belt sander, or in a random-orbit disk form? Maybe either would
work as long as the paper is kept cool and lubricated enough to keep
from loading up. I've thought of, for example, building a small
tabletop version of a woodworking stroke sander, using some standard 2"
wide belts and a coolant flood system. Maybe the finer grits would be a
leather belt and buffing compound?

Another alternative might be building some kind of rotating or
recipricating head into a small drill press, using the quill to apply a
gentle downward pressure.

I'm just surprised that I haven't seen any machine or components
available for doing this operation. It's got to be a fairly common
problem.

Thanks for your ideas!

Bruce Johnson
Johnson's Extremely Strange Musical Instrument Co.
Burbank, CA