"Bob La Londe" wrote in message
...
I need to put a smooth finish on the inside of some aluminum tube. 1"
ID smallest - 2" ID biggest. Same application different sizes. If it
was steel or cast iron I would just run a brake hone or cylinder hone
down it, but I think the stones would just pack up with aluminum if I
tried that with this. It doesn't need to be precise, just smooth. I
want to round off the weld seam (not to bad to begin with) and make it
fairly shiny inside. Flap wheels? Buffing wheel with a "course"
substitute for rouge? Other?



I have actually tried this on the inside of a half cylinder of aluminum for
optical purposes. With aluminum, smooth and shiny are not the same thing.
Aluminum has a very hard outer oxide surface layer. As you sand, you break
through parts of that and then gouge the soft metal underneath while the
remaining oxide protects other areas. Even fine grits will give a gray
pitted surface, although maybe thats shiny enough for what you want. The
easiest way to get moderately shiny, but not so smooth surface is careful
machining with kerosene.

If you want smooth and mirror shiny, I used a gradual progression of silicon
carbide paper down to 3000 grit with kerosene which supposedly prevents
forming new oxide. I then used red rouge on a soft buff for final polish,
but that is because that is what I had.

If you look on youtube, people have posted all sorts of particular methods
of polishing aluminum with all sorts of compounds, but they are all
tedious.