C.I.C.D.

C.I.C.D. follows the abandonment of the MK2 drum (judged not efficient enough). The thesis shifts from horizontal brute-force drum to a vertical spinner for vertical bite and self-righting potential, while keeping the reliable 4WD brushless drive that MK2 proved out. The real bot is a carbon-fibre-plate chassis (waterjet/laser CF, the cf_cuts tab) with 3D-printed hubs/mounts and the 8 mm Hardox weapon — not an all-printed robot.

The real build

Assembled C.I.C.D. — carbon-fibre twill chassis plates; the machined Hardox Snaggletooth blade on its belt pulley (toothed synchronous belt visible); the two Hardox front forks with ground edges; 4× knobby wheels; socket-head bolt assembly. More in the photo album.

Weapon — Vertical Spinner (single Snaggletooth blade)

Final design is a single blade, not the earlier twin-disc — the 1500 g budget doesn’t allow two. In the Onshape Weapon part studio the weapon is built from parts blade + bar on a hub (19 features; Revolve + circular-pattern teeth), selected in the assembly via the Forks configuration.

• Form factor: single Snaggletooth toothed blade/bar on the central hub/pulley.
• Blade design: the open-source Just’Cuz Robotics “Snaggletooth” (reference; CAD on their GrabCAD). Stock is 6″ / 0.25″ AR500 — we used the design but had it machined locally in 8 mm Hardox (not purchased from the store).
• Material: 8 mm Hardox (abrasion-resistant steel) — for both the blade and the front forks. Density ≈ 7.85 g/cm³ (matches the measured mass/volume).
• Blade mass: 277 g (0.277 kg — from Onshape mass properties, part blade; volume 35,270 mm³, density ≈ 7.85 g/cm³ confirms Hardox).
• Spin-axis inertia: Lxx = 374.4 kg·mm² → I ≈ 3.744×10⁻⁴ kg·m² (largest principal MoI = spin axis for a flat bar; Lyy 104.6, Lzz 272.8). Verify axis against the motor-shaft mate connector.
• Hub/pulley radius: 30 mm. Tooth-tip radius: TBD (measure tip-to-center).
• Drive: D2830 1000 kv, single belt 1:1 → weapon RPM = motor RPM. Weapon 50A ESC.

Computed performance (4S, 1:1)

• Weapon RPM: ~11,800 (1000 kv × 14.8 V × ~0.8 load) → ω ≈ 1236 rad/s
• Stored energy: ~286 J (E = ½·I·ω² with I = 3.744×10⁻⁴, ω = 1236).
• Tip speed: ~43–56 m/s (v = ω·r; firm up once tooth-tip radius is measured)

• Self-righting: vertical spinners often need it — TBD

To finalize (CAD)

• Confirm the spin axis (assumed Lxx = 374.4) against the motor-shaft mate connector → locks stored energy.
• Measure tooth-tip-to-center radius → locks exact tip speed.
• Belt ratio: ~1:1 (~286 J) now looks right; only revisit a step-up if impacts are weak.

Drive

• 4WD, 2× 2322 brushless + 25:1 planetary gearbox (one per side)
• Each motor mounts on the rear wheel and drives the front wheel via a single belt, 1:1 (no reduction) — changed from the MK2-style mid-mounted / dual-belt layout.
• Wheel pulley 22 mm; 56×28 RZ Lego tyres

Electronics & Power (per CAD)

• Drive ESCs: 2× 40A (one per side).
• Weapon ESC: 50A.
• Power distribution: XT30 distribution board (XT30_DIST_BOARD_LC).
• Battery: 4S 650mAh Tattu is the primary in the assembly; a 3S 850mAh MiniStar (carried from Lucille) also appears in the model — confirm which is the flight pack vs a leftover instance.

Control (inherited from Lucille MK2 / MK1)

• RadioMaster ER6 ExpressLRS 2.4 GHz PWM receiver
• EdgeTX radio — new model slot: CICD

Onshape Reference

Document: C.I.C.D. (Main workspace) on Onshape

Configurations (front-end variants): Clean (bare chassis), Forks (single-blade spinner — the competition build), Wedge.

Assembly instances (Forks config, 17): Body · drive motors · 4s650-tattu (battery) · 50A (weapon ESC) · 2× 40A (drive ESCs) · 3s850-MiniStar (battery) · 2× 56x28rz assembly (wheels: tire_56_x_28 + 56x28rz_sprocket + 625-zz bearing) · WeaponMountAssembly + Mirror 1 · XT30_DIST_BOARD_LC · Jackei-fork (weapon) · Assembly 1 · armor · M5×0.8×35 hex socket cap screw + M5 prevailing-torque thin nut (weapon shaft). 10 fastened mates.

Tabs: Assembly · Body · WeaponMountAssembly · WeaponMount · Weapon (parts: blade, bar, +2) · armor · old · cf_cuts (+ Sketch 1.dxf) · drive motors.

Renders (from Onshape, Forks config)

Captured 2026-07-14. Per the warning above, Onshape “Front” = robot rear — the fork/weapon side is the true combat front.

Isometric — full robot: 4WD chassis with “CICD” embossed, blue weapon-mount towers, drive belts, electronics tray, fork weapon at the front.

Front three-quarter — the two Hardox front forks extending forward, weapon blade behind them; drivetrain, PCB and weapon-mount exposed.

Weapon part studio — Hardox blade/fork plate (grey) + belt pulley & toothed hub (blue). Parts: blade, bar, +2.

Onshape Back = robot FRONT — the Snaggletooth blade + pulley centered, flanked by the blue weapon towers and drive wheels. The money shot.

Onshape Front = robot rear — “CICD” barrel, wheels, weapon towers behind.

Onshape Right = robot’s LEFT side — fork prongs, raised weapon arm, wheelbase.

Open design questions

Tip-speed target, weapon belt ratio (1:1 vs 2:1 step-up), armor spec, self-righting scheme, which battery is the flight pack, first event target. (Resolved from CAD: single-blade weapon, drive/weapon ESCs, power board, CAD document link.)