The Frame thread

[artdutra04]

Originally Posted by Grim Tuesday

We do have sheet metal capabilities, so I would be interested if any of the team IFI teams could show us how they do their frames, or just any sheet-metal teams.

We have two sheet metal machine shop sponsors, and have used sheet metal for our base chassis/drivetrain in 2007, 2009, 2010, and 2011. 2007 and 2011 were 6WD, 2009 was 4WD, and 2010 was independent swerve. Here's some photos of our 2011 drive train:







This drive train was an absolute tank. Everything shown in the top CAD model (chassis, gearboxes, wheels, chain, etc) came out to 37.4 lbs. Each of our 2-speed gearboxes (custom ones made from a la carte AndyMark gears) weighed less than a stock ToughBox, and were geared for speeds of 6 ft/sec and 16 ft/sec at nominal load. The center shaft is direct-driven from the gearbox output, with the end two wheels being powered by 25p roller chain. All shafts are 1/2" 12L14 steel hex, with all shafts being live axle (it's the simplest way to power Colson wheels). Except for the custom sheet metal and COTS AndyMark parts, all other fabricated parts could be made on a manual lathe.

Even without a belly pan, this chassis was extremely rigid and had no noticeable flex. Once assembled during the build season and run through its initial break in period, we haven't touched it. Nothing broke, nothing needed adjusting, nothing needed replacement.

Edit: If you're interested, I've posted the CAD model of our entire 2011 robot to CD-Media.

PROTIP: If you can't get powder-coating, use enamel spray paint. If you properly clean all parts ahead of time (e.g. use acetone) and let the paint cure for at least 24 hours, it's nearly as durable as powder-coating and much cheaper.