Aluminum

[maclaren]

We try to use 7075 plate whenever we have to machine things out on the mill.

We use 6061 or 6063 when ever we have to weld things together because 7075 is difficult to weld.

As for axles we have actually used 5/8" aluminum tube dead axles on our 2004 bot and never had any issues with the axles or wheels. The wheels never had any slop and ran smoothly the whole time. I think that the wall was .090" thick. We had the axle mounts directly butted up to our flanged plain bearings that were pressed into our wheel hubs so there was practically no unsupport length and next to no torsional load (only the friction from the bearings).

We typically get most of our aluminum from either our local steel supplier or scrap metal yard or order it from mcmaster-carr. Hopefully this year we can talk to a local aluminum mill thats about 1 hour away about donating so aluminum.

[Gary Dillard]

Keep in mind that welded 6xxx aluminum loses 75% of its yield strength (9ksi versus 35ksi) in the heat effected zone. Be sure and overdesign the joints.