"KEYBOTRAY" wrote in message
...

I got myself a 'keyboard arm' (http://tinyurl.com/chtfdey) for my
desk
and instead of paying $100 for their 'molded ABS tray'
(http://tinyurl.com/9hecxvz) I thought I'd make an aluminum one.

I want it to be 12" deep by 32" wide. The mounting surface on the
arm is
5 3/4" x 5 1/2" and it would mount in the center back of the tray.

I'd like it to be reasonably rigid, but I'm not going to be leaning
on
it with my upper body weight. I'd like to put a 1/4" - 3/8" bend in
the
back to stop the keyboard/mouse from sliding off so that should help
give it some structure.

I'm not crazy about putting any other bracing on the bottom, as I
want
the top surface to be as close to my legs as possible.


- What grade+thickness of al? I'd like to keep it at max 1/8" if
possible.
- I was thinking of getting it anodized for a finish, but I'm not
set
on that.
- I'd like to tap holes (they can go the whole way through) and
mount
from underneath to have a flat surface, but countersunk bolts would
work.
KEYBOTRAY

1/16" 6061 should be fine, but making a 32" long bend in it without
warping it will be very difficult without expensive tools or
experience. I would bend 1" or larger aluminum angle into a U frame
and screw or rivet a flat sheet to it. Then the metal's strength and
stiffness will continue around the corners. If you bend up flanges the
discontinuous corners will flex.

Practice notching and bending the angle with short pieces to see how
big a gap and radius you need to keep it from cracking.

The pan will be substantially stiffer if you put shallow diagonal
creases across it. Look at large panels in a commercial air ducting
system.
http://www.cadalyst.com/files/cadaly...CrossBrake.jpg

jsw