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Old 03-03-2010, 09:08 PM   #3060 (permalink)
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Originally Posted by MPaulHolmes View Post
Don't tell that to Oprah...

OK, McMaster Carr sells 2"x1"x12" pieces. That's a little longer than I would want, and it wouldn't be drilled yet, so I'm a little worried about that. I read that there are a few materials that can remove the coating over the areas where I'd have to drill it. Like Lye (which doesn't get along with Aluminum at all) and some other weird name like TPE or something. I don't know! man!
You mean removing hardcoat anodizing?
Don't do it with chemicals! Very, very nasty. Actually, I'm amazed it can be done that way.

Just use a center punch to mark the hole and penetrate the anodizing and then drill your holes. Use high-quality hardened bits (not HSS!) and have a few of them laying around as they'll dull quickly if you have a lot of holes to drill.

I'm slightly worried about using McMaster's anodized aluminum as they don't mention the surface thickness of the anodizing. If it's 2mils+, as is often done for just hardening a surface, the thermal resistance will be much higher than the 0.5mil surface (0.5mil penetration) thickness recommended for heat sink use.

But, a few tests can easily determine the thermal resistance of their anodized aluminum vs a raw Al bar.
John M.
CamLight Systems
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