Mill / Buff / Polish / Protect Aluminum?

The aluminum sheets I received today had some noticeable scratches in them (at least .3mm deep). Any advice on how to deal with them? I want my work to be flat-- I’m worried about weaknesses and rusting, as well as my own personal aesthetic dissatisfaction.

Aluminum doesn’t rust.
I use a wire wheel on a bench grinder to finish off edges after I mill aluminum. Don’t have a good solution yet for large surface finishing - I have been spray painting mine and they have turned out well.

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Aluminium is usually coloured and protected by anodising. A search will produce many links on doing this.

I use 80 grit sand paper on my aluminum sheets to remove the scratches. Then 220, then 400. I use a palm sander. They come out perfectly. After milling, then, you can tumble small pieces OR, hit it again with your 400 grit, then 800, and then, if necessary, 2000 grit. After that, its the buffing wheel. A short cut would be hit it again with your 400 grit and then rub it all in one direction with 000 steel wool. THat leaves a nice finish as well. To sand off tabs, I use my bench belt sander.

Easy peasy.

Depending on the accuracy level you’re after, you can just face-mill it and break the edges… or for ultra-high accuracy, you can have it surface ground…

As far as protecting it… aluminum with do that itself, it will form an almost invisible, very thin layer of oxide, once that happens, it won’t oxidize any further… However, keep caustic / acidic chemicals away from it… vinigar, soda, etc will pit the surface, and ruin any finish…

Hope that helps :slight_smile: