# Step 13: Join the Ankle Assemblies

> Join the leg assembly from Step 10 and the foot assembly from Step 12 with two M4x25 Socket bolts, then connect the ankle linkages with rod ends, steel bars, two M3 steel washers, and two M3x6 Socket bolts.

- Page: https://docs.menlo.ai/asimov/1/build/assembly-steps/left-leg-module/ankle-assembly/step-13
- Section: Asimov › Asimov 1 › Assemble Asimov 1 › Assemble › Left Leg Module › Ankle Assembly
- Previous: [Step 12: Assemble the Foot Pivot](https://docs.menlo.ai/asimov/1/build/assembly-steps/left-leg-module/foot-assembly/step-12.md)
- Next: [Step 14: Left Leg Verification](https://docs.menlo.ai/asimov/1/build/assembly-steps/left-leg-module/complete-left-leg-review/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 |
| - | -: |
| Leg assembly from Step 10 | 1 |
| Foot assembly from Step 12 | 1 |
| M4 nylon-insert nuts | 2 |
| M4x25 Socket bolt | 2 |
| Ball Joint Rod End (part `600_21X`) | 2 |
| 194 mm Stainless Steel Bar (part `600_23A`) | 1 |
| 124 mm Stainless Steel Bar (part `600_24A`) | 1 |
| M3x6 Socket bolt | 2 |
| M3 steel washer | 2 |

## Instructions

1. Take the leg assembly from Step 10 and put it on the surface such that the back side of the knee is facing upward towards the ceiling and the ankle is facing toward you.

2. Take **2 of** M4 nylon-insert nuts and slot them into the 2 holes at the ankle part, Make sure that the white nylon part is facing each other toward the center.

3. Take the foot assembly from Step 12 and slot part `600_25A` to fit into the ankle portion on part `600_10C`. Make sure that the holes are aligned with the locknuts.

4. Take **1 of** M4x25 Socket bolt and insert it into the hole on part `600_25A` from the heel direction and tighten it all the way to secure the part to Part `600_10C`.

5. Turn the current assembly 180 degrees so that the knee is now facing upward toward the ceiling.

6. Take **1 of** M4x25 Socket bolt and insert it into the hole on part `600_25A` from the toe direction and tighten it all the way to secure the part to Part `600_10C`.

7. Take the 194 mm Stainless Steel Bar and the 124 mm Stainless Steel Bar and thread each one onto its Ball Joint Rod End (part `600_19X`) on the foot assembly, as shown in the visualization below. You have to keep threading until you don't see any of the thread on the Ball Joint Rod Ends exposed anymore.

   > [!WARNING]
   >
   > **It is very important to do this right**
   >
   > Please watch the attached video to know how to do this as it has significant impact to the performance of the locomotion policy of the robot.

   Video: [Ankle bar installation](https://static.asimov.inc/manual/v1/videos/ankle-bar-installation.mp4)

8. Take **2 of** Ball Joint Rod Ends and thread each one into the top of one of the 2 bars above. Then, insert them onto part `600_17B` and part `600_18B`. Do the same thing as above to ensure you cannot see any thread left exposed on the Ball Joint Rod End.

9. Take **2 of** M3x6 Socket bolts and **2 of** M3 steel washers. Place each washer on each bolt separately and tighten it onto part `600_17B` and part `600_18B` to secure the 2 Ball Joint Rod Ends.