Fasteners & Rivets

Open with a real photo of an FRC drivetrain corner. Point out the rivets in the sheet-metal gussets and the bolts in the gearbox. Tell them: every place two parts touch, something holds them. In CAD we model that hardware so we can check clearance, weight, and that the bolt is long enough to actually grab the nut. Common student mistake: leaving holes empty and assuming 'it'll work in real life.'

If students came from the Onshape frcdesign curriculum, set expectations: there is no one-click rivet button in Fusion. The Fusion workflow is insert a hardware body, position it, and joint it. It is two more clicks but you get the exact same outcome and you can use ANY vendor's CAD. Reassure them this is normal and arguably more flexible.

Demo live: go to mcmaster.com, search a 1/4-20 socket head cap screw, scroll to the CAD download, pick STEP. Tell them McMaster part numbers are like magic words — write them in your BOM. STEP is the universal format Fusion reads. Mention REV Robotics, WestCoast Products (WCP), and AndyMark also publish STEP/F3D files for their gussets, gearboxes, and the MAXSwerve module.

Big tip: Fusion has a built-in McMaster-Carr browser under the Insert menu — you can search and place hardware without leaving Fusion. Demo it. When the part lands it is a loose component, sitting wherever it dropped, fully unconstrained. That is expected. The next step is to lock it down with a joint. Watch out: inserting many fasteners as full components can slow big assemblies — more on that later.

This is the core skill. Press J. Fusion uses 'joint origins' — selecting a circular edge gives you a snap point at the circle's center. Pick the bolt head's bottom edge, then the hole edge. Use a RIGID joint for fasteners — they don't move. Common mistakes: picking a flat face instead of a circular edge (no center snap), or flipping the bolt so it points out of the plate (use the Flip button). Revolute/slider joints are for moving mechanisms, NOT bolts.

Real robots have dozens of identical bolts. Teach them not to insert the STEP file 16 times — insert once, then copy/paste the component (paste keeps it as the same definition, so it's lightweight). Name your hardware clearly so the BOM reads well. For performance: you can suppress or hide fastener components when modeling structure, then turn them back on for renders and clearance checks.

Ground it in their robot. Frame corners: rivet gussets onto 2x1 1/16in wall tube. Gearbox to tube and swerve module mounting: 1/4-20 bolts into tapped holes or with nuts. NEO/Kraken motors bolt to the gearbox face plate with #10-32. When tube is too thin to tap, teams use rivet nuts (rivnuts) to get threads. Mention that bumpers are usually 1/4-20 bolts so they come off fast between matches.