Bellypan Pocketing

Anchor it physically: pass around a real bellypan or point at last year's robot. Stress that the bellypan does double duty — it's a mounting surface AND a structural shear panel tying the frame together. A solid 1/8in plate across a 28x28 frame can weigh 3-4 lb; on a 125 lb budget that matters. Today we make it lighter without making it floppy.

Core idea: stiffness comes mostly from the material at the edges and around hole bosses, not the middle of a span. So we can remove the center material with little stiffness loss. Use Modify > Physical Properties to show mass before and after live — a good pocket pattern often cuts 30-40% of plate weight. Warn: lightening is the LAST step, after holes and mounts are placed.

Use the Hole feature (not extrude-cut) so the holes are parametric and tagged as holes for the shop. Project actual mounting patterns from the gearboxes (MAXSwerve, MAXPlanetary, NEO/Kraken bolt circles) rather than typing coordinates — this guarantees alignment. Teach the clearance vs tap distinction: bellypans get clearance holes, the part above gets the threads. Leave a ring of solid material around every hole; pockets must respect that.

Triangulated or hex pockets keep shear stiffness far better than a few huge rectangular holes — same reason bridges use triangles. Hard rule for manufacturing: NO sharp internal corners. A router/end mill can't cut a zero-radius inside corner, so every internal corner needs a radius at least equal to the tool (1/4in end mill = 0.125in radius min; use 0.25in to be safe). Ribs thinner than ~0.18in get flimsy and hard to cut. Set rib width and pocket size as User Parameters via Modify > Change Parameters so the whole grid retunes from two numbers.

Demo Create > Pattern > Rectangular on the pocket cut feature. Set quantity and spacing, then use the pattern's suppression to delete instances that would cut into a mounting boss or run off the edge. Leave a continuous solid band (~0.5in) around the entire perimeter where the pan bolts to the frame — that border carries most of the load. Watch the live preview for ribs that get pinched thin between a pocket and a hole; fix by suppressing or shifting.

Tie design back to your actual shop. If you route on a Shapeoko/Onsrud, internal radii must match the bit. If you waterjet (or send to SendCutSend), corners can be tighter but you still avoid knife-edges. Mention that thin floating ribs can vibrate or break during cutting — keep them stout. Check the overall footprint fits a standard 24x24 or 24x48 sheet. The takeaway: a beautiful pocket pattern that can't be cut is worthless.

Always assign the real material (Modify > Physical Material > Aluminum 6061) or the mass readout is meaningless. Record before/after weight so the team sees the payoff. Then sanity-check: do battery, RoboRIO, PDH, and motor bolts still clear the pockets? Did any patterned instance eat into a hole's material ring? Fusion's parametric timeline makes fixes cheap — just edit the master sketch and the pattern updates.