# Mechanism

## Bill of Materials

### Servos

18 TowerPro [MG92B](http://www.towerpro.com.tw/product/mg92b/) are required.

> The dimension of 3d printed part is highly dependent on the servo's size. Modification is required if you want to use alternative servos.

### 3D-Printed Parts

#### Body x 1

| Filename       | Thumbnail                                                          | Required |
| -------------- | ------------------------------------------------------------------ | -------- |
| body_top       | <img src="./imgs/body_top.jpg" alt="body_top" width="300"/>       | 1        |
| body_bottom    | <img src="./imgs/body_bottom.jpg" alt="body_bottom" width="300"/>    | 1        |
| body_side_wall | <img src="./imgs/body_side_wall.jpg" alt="body_side_wall" width="300"/> | 2        |
| body_back_wall | <img src="./imgs/body_back_wall.jpg" alt="body_back_wall" width="300"/> | 1        |

#### Leg x 6

| Filename        | Thumbnail                                                                 | Required |
| --------------- | ------------------------------------------------------------------------- | -------- |
| thigh_top       | <img src="./imgs/thigh_top.jpg" alt="thigh_top" width="300"/>             | 1 (x6)   |
| thigh_bottom    | <img src="./imgs/thigh_bottom.jpg" alt="thigh_bottom" width="300"/>       | 1 (x6)   |
| joint_cross     | <img src="./imgs/joint_cross.jpg" alt="joint_cross" width="300"/>         | 1 (x6)   |
| joint_top       | <img src="./imgs/joint_top.jpg" alt="joint_top" width="300"/>             | 2 (x6)   |
| joint_bottom    | <img src="./imgs/joint_bottom.jpg" alt="joint_bottom" width="300"/>       | 2 (x6)   |
| leg_top         | <img src="./imgs/leg_top.jpg" alt="leg_top" width="300"/>                 | 1 (x6)   |
| let_bottom      | <img src="./imgs/leg_bottom.jpg" alt="leg_bottom" width="300"/>           | 1 (x6)   |
| foot_top        | <img src="./imgs/foot_top.jpg" alt="foot_top" width="300"/>               | 1 (x6)   |
| foot_bottom     | <img src="./imgs/foot_bottom.jpg" alt="foot_bottom" width="300"/>         | 1 (x6)   |
| foot_ground     | <img src="./imgs/foot_ground.jpg" alt="foot_ground" width="300"/>         | 1 (x6)   |
| foot_tip        | <img src="./imgs/foot_tip.jpg" alt="foot_tip" width="300"/>               | 1 (x6)   |
| servo_horn_j1j2 | <img src="./imgs/servo_horn_j1j2.jpg" alt="servo_horn_j1j2" width="300"/> | 2 (x6)   |
| servo_horn_j3   | <img src="./imgs/servo_horn_j3.jpg" alt="servo_horn_j3" width="300"/>     | 1 (x6)   |

### Others

| Name      | Spec    | Thumbnail                    | Required | Note                                              |
| --------- | ------- | ---------------------------- | -------- | ------------------------------------------------- |
| Screw     | M2 6mm  | ![6mm](imgs/M2_6mm.JPG)     | 54       | Servo Arm: 1 x 18<br>Joint: 4 x 6<br>Thigh: 2 x 6 |
| Screw     | M2 10mm | ![10mm](imgs/M2_10mm.JPG)   | 24       | Thigh: 1 x 6<br>Pin lock: 1 x 18                  |
| Screw     | M2 30mm | ![30mm](imgs/M2_30mm.JPG)   | 36       | Servo: 2 x 18                                     |
| Nuts      | M2      | ![6mm](imgs/M2_nut.JPG)     | 36       | Servo: 2 x 18                                     |
| Pin (304) | M4 6mm  | ![pin](imgs/pin_M4_6mm.JPG) | 18       | Servo: 1 x 18                                     |

## Leg Assemble

### Assembly video

<a href='https://youtu.be/oaAE5fC09KQ'><img src='http://img.youtube.com/vi/oaAE5fC09KQ/mqdefault.jpg'/></a>

### Exploded view

<img src="./imgs/mech_leg_exploded.jpg" alt="LegAssemble" width="500"/>

### Detailed steps

- **Step 1** - Combine `thigh_top`, `MG92B` and `thigh_bottom`, use M2x30mm screw and nut to secure them together.

<img src="./imgs/mech_leg_1.jpg" alt="LegAssemble1" width="500"/>

- **Step 2** - Grab one `joint_cross`, `joint_top` and `joint_bottom` and combine them

<img src="./imgs/mech_leg_2.jpg" alt="LegAssemble2" width="500"/>

- **Step 3** - First put 2 x `MG92B`, `leg_top` and `leg_bottom` together with M2x30mm screw and nut. Then attach `joint_top` and `joint_bottom` altogether

<img src="./imgs/mech_leg_3.jpg" alt="LegAssemble3" width="500"/>

- **Step 4** - Grab `foot_top`, `foot_bottom` and `foot_ground` (and `foot_top`) and assemble them.

<img src="./imgs/mech_leg_4.jpg" alt="LegAssemble4" width="500"/>

- **Finish** - Great, you got 1 leg done, 5 more to go :)

<img src="./imgs/mech_leg_5.jpg" alt="LegAssemble5" width="500"/>