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Unread 09-11-2007, 01:02
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Tristan Lall Tristan Lall is offline
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FRC #0188 (Woburn Robotics)
 
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Re: Cool Frame Ideas?

Quote:
Originally Posted by Binome View Post
Bosch Extrusion
Its really nice, and reusable between years.
You probably don't want to hear this, but I'll bring it up anyway....

Based upon past years' rules, and the ways that they've typically been interpreted, only the most trivially modified extrusions are actually reusable under the rules. Basically, for a part to be reusable from year to year, it needs to be COTS and unmodified. In the case of extrusions, while the different kinds of custom cuts that are possible make interpretation of the rule a little fuzzy, things like milled slots or bolt patterns are almost certainly going to be ruled as non-COTS, and therefore not legal for next year's robot. So be careful what you reuse!

Quote:
Originally Posted by dtengineering
If you can't TIG or MIG in-house, then keep in mind that somewhere in your community there is someone who wants to weld your robot for you. People who like welding tend to like welding cool things, and competitive robots are generally regarded as a pretty cool thing. Perhaps a local community college or trade school can help you out.
That's exactly what 188 tried one year (2006). We ended up with a very unconventional welded sheet metal frame. We also had a few too many crazy robot issues happening simultaneously, and nothing on that robot really got fine-tuned very well. Despite that, I'd like to see more of that sort of semi-monocoque aluminum frame—not because it's necessarily the most effective, but because it's an interesting engineering challenge. In the case of the 2006 robot, 188 recruited the services of a local engineering and fabrication company, but the community college suggestion is an excellent one. (As a matter of fact, for teams in Southwestern Ontario, there's a nice welding lab at Conestoga College in Guelph that might be worth talking to—I can supply contact details if anyone's interested.)

One last thing about welding aluminum: by virtue of the way aluminum heat-treatment works, fusion welding (i.e. when metal melts) almost invariably results in a weld that is weaker than the base metal. So even though you might be welding 6061-T6 extrusions, you might have to use a welding rod that deposits 4043-O filler metal* (which is far weaker). There's one thing that would be even more impressive than trying the fully-welded chassis: building a frame jig which would hold the entire frame rigidly while you heat-treated it in a large oven, back to a high-strength T6 condition.

*More precisely, it's actually -F with properties equivalent to -O, because it wasn't deliberately annealed, rather it just came out that way.