Hardware — salamander-v2 body

Bill of materials

• 1x RP2040 Pico W (controller)
• 6x SG90 metal gear 9g servos (legs + spine)
• 1x BNO055 IMU breakout
• 1x 2S 500mAh LiPo (power)
• PLA+ body (eSun matte black, 0.2mm layers, annealed)
• Silicone rod (spine, to be replaced with vertebrae)
• M2 screws, heat-set inserts

Print settings

Printed on Bambu X1 Carbon. 0.2mm layer height, 3 walls, 20% gyroid infill. Annealed at 70C for 8 hours in a food dehydrator. The annealing step is important — without it the leg sockets creep under repeated load.

Assembly notes

Leg sockets were tight out of the printer. Reamed with a 3mm drill bit. The fit is now snug but removable without tools. The servo horns are press-fit into the printed couplers — this is the weakest joint in the assembly and will need a redesign (probably a clamp collar).

Known issues

The spine joint is the biggest problem. The single silicone rod bows instead of articulating at discrete points. The next revision replaces it with rigid PLA discs on a tendon.