3.4 Implementation
Manufacturing and Assembly
Fabrication of our components took various forms. The base plates of the structure were laser cut clear acrylic. The legs for the 4 bar structure were also made of laser cut acrylic pieces. The motor mount and L brackets to connect the base plates were 3D printed with PETG. The gears were also 3D printed PETG. The tolerances for all manufacturing parts were tight to reduce gear slop and increase the ease of control of the legs.
The bearings, hex shafts, fasteners, and washers were outsourced. We used M4 screws and low friction washers to allow for ease of movement between the legs.
The assembly involved assembling the base structure first and assembling the legs separately. Then the legs were mounted onto the base in a specific order to create constant movement by having enough legs on the floor at all times to be balanced and generate forward motion.
The scope of this project was just to create forward motion, so electronics involved a simple switch, motor, and battery circuit sufficed.
Bill of Materials
Part | Dimensions / Specification | Purpose | Quantity | Price | Source |
|---|---|---|---|---|---|
Ball Bearings | 608-2RS | Low-friction joints | 24 | $6.00 | PGN 608-2RS Bearings Pack |
PETG Filament | 1.75mm diameter | Structural links, mounts | 1 | $0 | TIW |
TPU Filament | 1.75mm diameter | Foot pads (traction/compliance) | 1 | $0 | TIW |
DC Gear Motor | 12V, 100 RPM, ≥10 kg·cm torque, 6mm D-shaft | Drives crank linkages | 2 | $7.00 | In Bins or Amazon |
Motor Driver | L298N dual H-bridge, 5–35V input | Controls motors | 1 | $7.00 | In Bins or Amazon |
Battery Pack | 12V | Power supply | 1 | $0 | In Bins |
Acrylic Sheet (Chassis) | 300mm × 200mm × 5mm thickness | Main frame | 1 | $0 | TIW |
M4 Bolts | M4 × 20mm length | Fastening | 40 | $0 | M4 Assorted Bolt Kit |
M4 Nuts | M4 standard hex | Fastening | 40 | $0 | Same kit |
M4 Washers | 4mm ID × 9mm OD | Fastening | 40 | $0 | Same kit |
Shaft Coupler | 6mm to 8mm coupler | Motor → crank linkage | 2 | $7.00 | Amazon |
Steel Shaft (Crank) | 8mm diameter × 100mm length | Rotating crank axis | 2 | $7.00 | Amazon |
Wiring | 22 AWG stranded, ~2m total | Electrical connections | 1 set | $5.00 | Amazon |
Toggle Switch | 12V, ≥5A rated | Power control | 1 | $5.00 | Amazon |
Part | Dimensions / Specification | Quantity | Material | Fabrication | Purpose |
|---|---|---|---|---|---|
Link Bars (4-bar sets) | 120–180mm length, 10mm width, 6mm thickness | 16 | PETG | 3D printed | Main linkage system |
Foot Arms | 120mm length × 10mm width | 4 | PETG | 3D printed | Extend foot to ground |
Foot Pads | 40mm diameter × 5mm thickness | 4 | TPU | 3D printed | Grip + shock absorption |
Bearing Housings | 22mm OD press-fit, 8mm ID | 24 | PETG | 3D printed | Mount bearings |
Motor Mounts | Sized to motor (≈60×60×5mm) | 2 | PETG | 3D printed | Secure motors |
Chassis Mount Plate | 300×200×5mm (laser cut holes for mounting) | 1 | Acrylic | Laser cut | Structural base |