[Rickertsen2]

I once had a job assembling 8020 structures for a distributor and have used it since then on many other projects. We also built a robot out of it back in 2002 so i feel i speak from experience.

8020 Pros:
You can very quickly prototype things and move them around. It doesn't need welding which is a huge plus if you don't have good access to a TIG welder. This and the fact that we got it for free were the reasons we used ut. If you want to be able to move things around then use brackets or anchor fastners. Keep in mind the weight of brackets. If you want something thats strong and don't plan on moving it use end fasteners. Even if your not making a frame out of 8020 they make some very nice parts that come in handy. For a FIRST robot frame i would reccomend 10 series if you are designing in inches or 25 series if you are metric. 15 series or 40 series is overkill. 8020 is a great material and certianly makes for flexibility. In a fast paced design challenge like FIRST this is useful.

8020 Cons:
An 8020 Structure will be both heavier and more expensive than an equivilant welded structure from square or round. You have less freedom with wall thicknesses and there is a lot of mass concentrated in the center of the profile which does little for stiffness. It is particularly week in torsion. Keep in mind the weight the fasteners add.

Drop in T-nuts are your friend. get plenty of these. If you plan on using end fastners , get the jig so that you can drill the clearance holes painlessly. Thre is a fixture for milling the holes for anchor fasners but you don't really need it. Make sure you have a few ball allen wrenches in the appropriate size.

Also there are some older threads about this topic if you dig em up with the search