# Step 1: Mount the Shoulder Actuator

> Mount actuator ID 18 in part 300_04B and secure it with threadlocked M4x8 Flat bolts.

- Page: https://docs.menlo.ai/asimov/1/build/assembly-steps/right-arm-module/shoulder-joint-assembly/step-1
- Section: Asimov › Asimov 1 › Assemble Asimov 1 › Assemble › Right Arm Module › Shoulder Joint Assembly
- Previous: [Step 14: Left Arm Verification](https://docs.menlo.ai/asimov/1/build/assembly-steps/left-arm-module/final-assembly/step-14.md)
- Next: [Step 2: Attach the Shoulder Base and Route the Cable](https://docs.menlo.ai/asimov/1/build/assembly-steps/right-arm-module/shoulder-joint-assembly/step-2.md)

> [!IMPORTANT]
> **Assign actuator IDs before assembly**
>
> Assign and verify all 25 actuator IDs before assembling the robot. The robot will not work correctly with missing or incorrect IDs. IDs must be assigned one actuator at a time on the bench; you may need to disassemble the robot if you skip this step. See [Assign Actuator IDs](https://docs.menlo.ai/asimov/1/build/assembly-preparations/assign-actuator-ids.md).

## Parts needed

| Part | Count |
| - | -: |
| EC-A5013-H17-100 actuator (part `300_17X`) (ID 18) | 1 |
| `300_04B` | 1 |
| M4x8 Flat bolt | 12 |
| Threadlocker | As needed |

## Instructions

1. Put the EC-A5013-H17-100 actuator (ID 18) on a flat surface, the port should be at the bottom, and the actuator shaft should be upward toward the ceiling.

2. Take Part `300_04B` and put the actuator through the center of the part, and align the holes on the actuator with the holes around the circumference of the Part `300_04B`.

3. Using **12 of** M4x8 Flat bolts, tighten each of them lightly into the holes, to keep the actuator and Part `300_04B` aligned first.

4. After the parts are aligned:

   > [!NOTE]
   >
   > **Not ready to apply threadlocker?**
   >
   > You can assemble without threadlocker while you check the fit, alignment, and orientation. When you are confident, disassemble as needed, apply threadlocker to the bolts, and reassemble them following these instructions.

   - remove **12 of** M4x8 Flat bolts one at a time in a star formation,
   - apply threadlocker,
   - then tighten them back to secure Part `300_04B` and the actuator together.