What materials do you most commonly use on your robots?

[Oblarg]

Originally Posted by MichaelBick

I love using box tubing because we have the machining resources necessary to fabricate with it and it permits us to build extremely light robots, but 8020 can be just as good if you need to build quickly with little resources.

It is not true that you need significant machining resources to do tube framing; 449 has had a very easy time of knocking together gusset plate/tube constructions using pre-machined 80/20 gussets and match-drilling everything. This allows you to clamp everything in its correct configuration before drilling, and allows lots of slop with the actual drilling (if you're careful you can actually get away with doing pretty much the whole thing with a hand drill without any trouble, though a drill press is better).

I've found that the problem with 80/20, in addition to the absurd weight, is that it makes it very easy for people to get into the habit of making things which "sort of fit together" instead of things which actually fit together; the play inherent to the system allows you to nudge things around when you haven't really figured out where everything should be. This is very useful when you're prototyping, but it is the enemy of a good final product. You end up with things that gradually walk out of position and you get lots of silly, avoidable failure modes which shouldn't be there.

One can alleviate these issues to an extent with judicious use of locking hardware/loctite and through-drilling, but I find it more effective at that point, both practically and pedagogically, to simply manufacture the final product out of a better, lighter material. If you stick with 80/20 it takes a fair bit of wherewithal to ensure that all your important dimensions end up fixed and secured, whereas if you switch to manufacturing the final product you are essentially forced to do it right, else you can't construct the thing.

So, it's not really so much that 80/20 can't be used well on a final robot so much as there is a lot of potential for it not to be used well compared to other materials. Also, did I mention it's heavy?