Quote:
Originally Posted by Jon Stratis
Last year, I saw team with a bunch of 80/20 on their robot come in 30+ lbs over the weight limit at a pre-ship scrimmage... I believe they made the limit just by replacing that with simple 1" square stock.
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Regarding the weight issue, be careful how you replace 80/20. The common (and lightest) 1" square profile (
1010), is .5097lb/ft. Compare to different 6061-T6 Al profiles.
lb/ft............Extrusion Profile..............................Length req. for -30lbs
0.513.........1" (1/8") square tube......................N/A
0.5097......80/20 1010 Profile.......................N/A
0.410.........1" (1/8") channel.............................301ft
0.285.........1" (1/16") square tube....................134ft
0.280.........1" (1/8") angle......................,.........131ft
Values vary slightly, primarily depending on the exact extrusion spec (AA, AS, etc).
Depending on your application, you'll likely be able to get away with lighter-weight extrusions in many situations (U-channel is usually* a reasonable structural substitute), but it's not as big a difference as many think.
*As in not always.