Problems w/ cast aluminum

[sthomag]

I have a problem that is driving me crazy. I'm polishing a cast aluminum motorcycle clutch cover, for an old Ducati. There seems to be an irregularity in the structure of the metal itself: some small areas are harder than others. It's as if when it was cast, the alloy wasn't consistent. This is apparent even when sanding the metal: there's a pattern that shows up.

When polishing with a 3/4 hp buffer, 8" spiral wheel, and black compound, this results in smeary-looking ripples and other irregularities. This is only true in two places on the cover; the rest is polishing up nicely.

I have a Dynabrade hand-held belt sander, and I'm going to try using non-woven conditioning belts to try to even out the surface better. Any other hints or suggestions?

[mpierich]

Originally Posted by sthomag

I have a problem that is driving me crazy.

Hmmm that sounds familiar...the voices in my head say that all the time, lol...

Originally Posted by sthomag

there's a pattern that shows up.

Personally I don't think there's anything to be done for it. Looks sorta like wood grain, no? If it's totally unacceptable maybe you should have it powdered with fake chrome or something like that. At least you have it nice and smooth now...

[berndog]

did you try using a greaseless compound on a spiral sewn wheel?,this might make the difference