# Step 1: Install the Waist Yaw Actuator

> Mount the waist yaw actuator in the pelvis housing.

- Page: https://docs.menlo.ai/asimov/1/build/assembly-steps/pelvis-module/pelvis/step-1
- Section: Asimov › Asimov 1 › Assemble Asimov 1 › Assemble › Pelvis Module › Pelvis
- Previous: [Step 14: Right Leg Verification](https://docs.menlo.ai/asimov/1/build/assembly-steps/right-leg-module/complete-right-leg-review/step-14.md)
- Next: [Step 2: Install the Left Hip Pitch Actuator](https://docs.menlo.ai/asimov/1/build/assembly-steps/pelvis-module/pelvis/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 |
| - | -: |
| Paper tape | As needed |
| EC-A6416-P2-25 actuator (part `200_10X`) (ID 23) | 1 |
| `200_16A` | 1 |
| M4x10 Flat bolt | 8 |
| `200_01C` | 1 |
| M4 square nuts | 8 |
| M4x18 Socket bolt | 8 |
| Threadlocker | As needed |

## Instructions

1. Take EC-A6416-P2-25 actuator (ID 23) and lay it flat on a surface such that the actuator shaft is facing upward toward the ceiling, the port should be nearer to the bottom.

2. Take part `200_16A` and align the 8 holes in the inner circumference of it with the 8 threaded holes on the actuator casing. Make sure that the port cut out on part `200_16A` is 45 degree away to the right of one of the cable ports at the bottom.

3. Take **8 of** M4x10 Flat bolts, lightly tighten into the 8 inner holes of part `200_16A` to align the part with the actuator.

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 **8 of** M4x10 Flat bolts one at a time in a star formation,
   - apply threadlocker,
   - then tighten them back to secure Part `200_16A` and the actuator together.

5. Take part `200_01C` and put it on the surface such that the hollow part points upward towards the ceiling and the two side round holes for the hip pitch actuator are pointing to the left and right sides and not facing down. Make sure the solid part faces towards you and the rectangular hole faces away from you.

6. Take **8 of** M4 square nuts and put them into the 8 slots around the holes in the inner circumference of Part `200_01C`. You can use paper tape to help you secure the nuts for ease of moving.

7. Align part `200_16A` and the actuator such that the port cut out and the port on the actuator is pointing out toward the rectangular cut out. Make sure that the 8 outer holes are aligned with the holes on the surface of Part `200_01C`.

8. Take **8 of** M4x18 Socket bolts, lightly tighten into the 8 outer holes of part `200_16A` to align the part with part `200_01C`. Once the part is aligned, tighten each of the **8 bolts** to secure the part together.