WEEK 10
Arms + Battery + RaptorX Integration
Upgrade arms to welded steel structure with bus servos. Bigger battery. RaptorX onboard providing 3D spatial awareness.
Est. Hours
35h
Est. Spend
$700
Tools Required
MIG welderwelding tableRaptorX scannersoldering ironhand tools
CAD FILES
arm_frame_welded_steel.sldasmbattery_bay_enlarged.dxf
PRINT FILES
finger_assemblies_v2.stl
Goal
Upgrade the arms and battery while integrating the scanner as an onboard sensor. You’ve been using the arms for 2+ weeks and know exactly where they’re weak.
Day-by-Day Tasks
| Day | Task | Method | Notes |
|---|---|---|---|
| 1 | Order ASME-MDB bus servos x4 | AliExpress/eBay ~$250 | Replace MG996R at wrist/grip positions. Bus protocol = daisy-chain wiring. |
| 1 | Order 24V 50Ah LiFePO4 | Amazon ~$400 | Replace 30Ah. List 30Ah on eBay (-$120 resale). Net: ~$280. |
| 1 | Order JLCPCB custom power distribution PCB | JLCPCB ~$40 | Design in KiCad. Order 5 copies. 1-2 week lead time. |
| 1-2 | Weld steel arm structure (replace aluminum tube cores) | MIG welder, mild steel tube | Weld arm frames from steel tube + flat bar. Grind smooth. Most precise welding work — do it with arms OFF the robot, on a flat welding table. |
| 2-3 | RaptorX: Scan welded arm frames | RaptorX | Verify straightness, joint alignment. Compare to CAD. Fix any warping before installing servos. |
| 3-4 | Transfer servos to new arm structure | Unbolt from aluminum, rebolt to steel | ASME-04B shoulder/elbow/forearm servos stay. MG996R at wrist/grip get swapped to ASME-MDB bus servos. |
| 4-5 | Upgrade finger mechanism | Per-finger micro servos (replace 2-per-hand SG90) | 3D print new finger assemblies. More dexterous grip — each finger independently controlled. |
| 5 | Reinstall arms on torso | Bolts through shoulder plates | Welded steel arms are heavier — verify shoulder servo torque is adequate. |
| 5-6 | Install 50Ah battery (when it arrives) | Swap in battery bay | May need to enlarge battery bay walls (laser cut new steel, weld in place). |
| 6-7 | Mount RaptorX on J5 | Quick-release dovetail mount (from Week 9) | Head mount: scanner aims where J5 looks. Connect via WiFi 6 to Pi 5. |
| 7 | Configure RaptorX perception software | Open3D, ROS2 node, Python | Scan room. Build 3D mesh. Publish as PointCloud2 topic. Nav2 consumes for path planning. |
| 7 | Test 3D perception | Walk J5 into a room, scan, navigate | ”J5, what’s in this room?” → J5 scans, identifies objects, plans path around obstacles. |
Skills Practiced
Precision welding (arm frames), bus servo wiring (daisy-chain), 3D perception software (Open3D + ROS2), KiCad PCB design.
Print Queue
New finger assemblies + replacement parts as needed