cavelamb wrote:
wrote:



WIth pencils, the issue is the graphite. There is a similar problem
if steel wool is used on aluminum.

A lot of sandpapers use Aluminum Oxide (Alundum) grit. That is
the same oxide that forms naturally on aluminum so that should not
be a problem. But most of the wet/dry papers use silicon carbide,
(carborundum) which may be a problem.


You don't sandpaper the edges - you file them...

The trick to good looking parts is finishing the edges.

Are they smooth, flat, free of nicks and scratches?

Sandpaper alone won't do that...


I agree that file would be better. Consider 'draw filing', which
is done by holding the file like drawknife which reduces the
angle of attack of the teeth and produces a finer finish.
Do you load a file with soap or something to keep soft
metals like aluminum from sticking in the teeth?

Sandpaper on a rigid sanding block would work too. I
personally _hate_ sanding so would much rather use
files, scrapers, stones, or burnishing tools.

Would you ever use sandpaper to prepare Aluminum for
epoxy, or rely entirely on chemical pre-treatment?

--

FF