From Team 449 Wiki
80/20 is a modular prototyping and framing system centered around aluminum pieces with slots in them. These pieces are assembled using brackets, bolts, and special nuts that slide into the slots. Since the nuts are held in place only by pressure from the bolt, pieces can be easily moved around. This, along with the fact that holes don't have to be drilled, makes 80/20 very useful for working out geometry and building early-stage prototypes.
|Bolt||Screws into nuts to hold things together.||Just a socket-head 1/4-20 bolt.||tk|
|Nut||Moves freely in slots when loosened. This is useful for adjusting geometry.||-||tk|
|80/20 stock||The mainstay of 80/20. You bolt these together to build things. Made of 6105 aluminum.||Should not be used structurally on the robot; use aluminum tube instead. It's much stronger.||tk|
|Bracket||Used to hold pieces together. Stronger than gusset plates. The 2x2 triangle ones (see picture) are the strongest.||Protip: Put bolts and loose sliders on first, then silde the brackets onto 80/20 stock so you can tighten the bolts. You can use these on aluminum tube as well.||tk|
|Gusset plate||Used to hold things together when a bracket won't do (usually, at a non-right angle).||Put gusset plates on both sides of the joint if you can.||tk|