> spec’d full electronics stack — esp32-wroom-32e, 2x pca9685 expanders on shared i2c (0x40 / 0x41), 13x mg996r flexors, 5x corona ds843mg abductors
> split-load power: two 12v→6v bucks, one per pca9685, sidesteps paralleling tolerance issues without losing per-board current headroom
> sized tendon spools from joint travel back to servo rotation. flexor needs 7mm pull, mg996r usable rotation ~135°, lands at ~20-25mm spool. abductors 6-8mm, wrist 14mm for 16.5mm travel per side
routed tendons through forearm with ptfe / printed rigid channels in high-load zones, pvc sleeve only through joint flex sections. convergence routing ≤15-20° per clip, tight clip spacing through bend zones

> forearm interior, 2-column x 6-row mg996r packing. electronics dorsal-mount behind access panel. petg shell, m3 heat-set inserts
> outer shell design over structural forearm. contributed to finger and palm mechanical design

> fully assembled, mechanically complete
electrical stack bench-validated. 18-channel i2c control, both pca9685s addressable, servo rails stable under load
> firmware and position feedback still in progress