pic: Team 293's Robot

[Cyclotron]

We counterbore clearance holes for 1/4-20 socket head cap screws (17/64 body, 25/64 head) and screw them into the tapped ends of the extrusion. McMaster sells a step drill bit to do this in one operation (drill press only!) Where 2 or 3 bolts would conflict at a corner, we use 8020 "end fasteners' which require only a #7 clearance hole for the hex key to tighten. Occasionally we use 8020 "anchor fasteners" which require a 9/16 counterbore in one extrusion.

We have done 45 degree and other angled connections. These require a careful drilling setup because of the profile shape.

These connections remain tight without locktite, but we always check everything just in case.

All of the fabrication steps for an 8020 frame can be learned by new team members very quickly, and the results are precise and as strong as they need to be. An 8020 frame is easier to put together than the Kitbot, and it is stronger, stiffer, and straighter.