# Step 7: Connect and Join the Shoulder Assemblies

> Connect the XT30 (2+2) connector to actuator ID 14, solder the corresponding cable conductors from actuators ID 13 and ID 14, and join the shoulder and upper arm assemblies with plates 400_03A and 400_01A and threadlocked flat bolts.

- Page: https://docs.menlo.ai/asimov/1/build/assembly-steps/left-arm-module/shoulder-and-upper-arm-connection/step-7
- Section: Asimov › Asimov 1 › Assemble Asimov 1 › Assemble › Left Arm Module › Shoulder + Upper Arm Connection
- Previous: [Step 6: Close the Shoulder Actuator Housing](https://docs.menlo.ai/asimov/1/build/assembly-steps/left-arm-module/upper-arm-assembly/step-6.md)
- Next: [Step 8: Attach the Shoulder Yaw Joint Plate and Shaft Mount](https://docs.menlo.ai/asimov/1/build/assembly-steps/left-arm-module/shoulder-and-upper-arm-connection/step-8.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 |
| - | -: |
| Shoulder assembly from Step 2 | 1 |
| Upper arm assembly from Step 6 | 1 |
| 100 mm single-ended XT30 (2+2) cable | 1 |
| `400_03A` | 1 |
| `400_01A` | 1 |
| M4x12 Flat bolt | 8 |
| M3x16 Flat bolt | 6 |
| Threadlocker | As needed |
| Approved soldering and insulation supplies | As needed |

## Instructions

1. Connect the XT30 (2+2) connector of the 100 mm single-ended XT30 (2+2) cable to the port on the shoulder roll EC-A4315-P2-36 actuator (part `400_18X`) (ID 14) in the upper arm assembly.

2. Solder each corresponding conductor from the cable leads routed from the EC-A5013-H17-100 actuator (part `400_17X`) (ID 13) to the cable leads connected to actuator (ID 14), following the released pinout.

   > [!WARNING]
   >
   > **Follow the video below for the soldering process**
   >
   > Follow the video below for the soldering process to make sure that the connection is made correctly else it can cause signal infidelity in the system.

   Video: [How to solder two wires together](https://www.youtube.com/watch?v=NSqPHQ1zQco)

3. Lay the upper arm assembly on its side such that the part with the bearing faces upward.
   Lay the shoulder assembly on its side such that the holes on part `400_02A` face upward. This part is symmetrical so any side is fine.

4. Align the protruded portion of part `400_03A` with the bearing, then align the 4 holes arranged in a moon shape with part `400_02A` from the shoulder assembly.

5. Take **4 of** M4x12 Flat bolts and lightly tighten into the 4 holes on part `400_03A` to align the part with part `400_02A`

6. 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 **4 of** M4x12 Flat bolts one at a time,
   - apply threadlocker,
   - then tighten them back to secure Part `400_03A` and part `400_02A` together.

7. Now flip the entire assembly to the opposite side, with the actuator shaft on the upper arm assembly facing upward.

8. Align the 6 circular holes on part `400_01A` with the 6 threaded holes on the actuator shaft, then align the 4 moon-shaped holes with the 4 threaded holes on part `400_02A`.

9. Take **6 of** M3x16 Flat bolts and then lightly tighten them in the 6 holes arrange in a circle on Part `400_01A` to the actuator shaft.

10. 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 **6 of** M3x16 Flat bolts one at a time in a star formation,
    - apply threadlocker,
    - then tighten them back to secure Part `400_01A` and the actuator together.

11. Take **4 of** M4x12 Flat bolts and lightly tighten into the 4 holes arrange in a moon shape on part `400_01A` to align with part `400_02A`.

12. 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 **4 of** M4x12 Flat bolts one at a time,
    - apply threadlocker,
    - then tighten them back to secure Part `400_01A` and part `400_02A` together.