So, for my day job I'm working on a circuit board design to replace something which features a heatsink made from aluminum angle. It's 1" x1" x 1/4", with nice square corners everywhere (radius < 0.02").
Up to now I've been blithely assuming that this is an off-the-shelf item that I can get anywhere -- but it looks like it may be harder to get than that. Worse, I'd really like to extend the heat sink another 1/2" or even 1" under the board, while keeping the outside leg at 1".
So I want to specify something that won't have their mechanical engineers muttering under their breath _too_ much about @#$% EEs with time on their hands...
McMaster carries aluminum angle, but it describes the inside corner and the inside ends of the legs as "rounded", without saying what the radius is. I can handle a radius on the inside corner, but that radius on the leg takes away from area that I want touching my board. Furthermore, McMaster only carries angle with even-length sides.
So my questions are:
Is there any commonly-available aluminum angle that has corners that one wouldn't describe as "rounded"? From who?
If I must go with rounded corners, can I expect that there is a standard? What is it? Is there a place I might find it on the web? (Machinery's Handbook doesn't seem to list anything like that).
Is there any commonly-available aluminum angle with uneven leg lengths? I'm specifically looking for 1" x 1.5" x 1/4", or 1" x 2" x 1/4". From who?
Any notion of how much it might cost to have a machine shop take a larger angle and whack it down? These need machining anyway: they have to be cut to length, then drilled on both webs and tapped on one -- so it would be a case of "while it's in the machine anyway, make one or two additional cuts". Precision is nearly nonexistent: +/- 0.05" would be fine, and finish wouldn't be a huge issue: as long as the edges are deburred and the cut side isn't so rough that it draws blood when handled things would be fine; I would expect that a decent shop with even a minimal sense of pride would insist on a much better finish than necessary to get the job done.