[Anodizer]

All extrusions are made for the 6000 series aluminum. We use 6061 and 6063.
I anodizes real well. I should know, I am the one that does it!
The problem is the piece has no rigidity because it is so thin. You need to support the piece to mill it. Also, a mill drill bit does not have enough slope for milling aluminum. Aluminum bits have a very slow ramp. You should use on for aluminum and a two cutter style. Use a lubricant as aluminum will weld itself to a bit because of its softness.
You piece is probably Type II anodized, the most common. If, by chance it is Type III, you will have problems as its surface has the hardness of sapphire.
To do anything with Type III you usually have to grind the anodize off of the area.
I makes me feel miserable when I do an A+ anodizing job and a professor made a mistake in his drawing. See the anodize being machined just does me in.

Fred Mahone