# Step 13: Connect the Shoulder and Elbow Assemblies

> Connect the leads from actuators ID 15 and ID 16 with four WAGO connectors, join parts 400_15C and 400_06B with six threadlocked M4x12 Socket bolts, and stage twelve M4x30 Socket bolts for torso installation.

- Page: https://docs.menlo.ai/asimov/1/build/assembly-steps/left-arm-module/upper-arm-and-forearm-connection/step-13
- Section: Asimov › Asimov 1 › Assemble Asimov 1 › Assemble › Left Arm Module › Upper Arm + Forearm Connection
- Previous: [Step 12: Install and Connect the Wrist Actuator](https://docs.menlo.ai/asimov/1/build/assembly-steps/left-arm-module/forearm-assembly/step-12.md)
- Next: [Step 14: Left Arm Verification](https://docs.menlo.ai/asimov/1/build/assembly-steps/left-arm-module/final-assembly/step-14.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 and upper arm assembly from Step 8 | 1 |
| Forearm assembly from Step 12 | 1 |
| WAGO connector | 4 |
| M4x12 Socket bolt | 6 |
| M4x30 Socket bolt | 12 |
| Threadlocker | As needed |

## Instructions

1. Position the shoulder and upper arm assembly and the forearm assembly so the color-coded cable leads from the EC-A3814-H14-107 actuator (part `400_20X`) (ID 15) and the EC-A4310-P2-36 actuator (part `400_22X`) (ID 16) are accessible. Insert each corresponding conductor pair into four WAGO connectors according to the released pinout, inspect each connection, and place the joined cable leads inside part `400_15C`.

   > [!WARNING]
   >
   > **Follow the video below to use a WAGO connector**
   >
   > If you have never worked with a WAGO connector before, follow the video below to strip, insert, and check each wire before continuing.

   ![The shoulder and upper arm assembly and the forearm assembly laid end to end, with their cable leads joined by WAGO connectors between them](https://docs.menlo.ai/manual/v1/images/arm-module/wago-connect-two-components.webp)

   ![Close-up of the red, white and black leads clamped in orange WAGO 221 lever connectors](https://docs.menlo.ai/manual/v1/images/arm-module/wago-connection.webp)

   ![The joined WAGO connectors tucked inside the hollow of the arm housing before the two assemblies are fitted together](https://docs.menlo.ai/manual/v1/images/arm-module/wago-insert-inside.webp)

   Video: [How to use a WAGO connector](https://www.youtube.com/watch?v=29xBbLo0ORY) (watch 0:26 to 1:30)

2. The shoulder and upper arm assembly and the forearm assembly should be connected to each other as follows. The actuator elbow part should be on the same side as part `400_03A`. The orientation of the forearm assembly is very important as it will dictate the rotation limit of the arm, so make sure you oriented it exactly as shown below.

3. Fit the forearm assembly onto the shoulder and upper arm assembly such that the 6 holes on circumference of part `400_15C` is aligned with the 6 holes on circumference of part `400_06B`.

4. Take **6 of** M4x12 Socket bolts and lightly tighten into the 6 holes on the circumference of part `400_15C` to align with part `400_06B`

5. 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** M4x12 Socket bolts one at a time in a star formation,
   - apply threadlocker,
   - then tighten them back to secure Part `400_15C` and part `400_06B` together.

6. Take **12 of** M4x30 Socket bolts and insert it into the 12 holes on part `400_04B`. This will be used later to install the left arm module to the torso module. If the shoulder part is blocking you from insert the bolt, use a bit of force to rotate the actuator around so you can slot the bolt in.