# Mechanism
## Bill of Materials
### Servo - MG92B
Servo is the key component. I use TowerPro [MG92B ](http://www.towerpro.com.tw/product/mg92b/ ). It has metal gear (important!).
An hexapod requires 18 of them.
> The dimension of 3d printed part is highly depended on servo's dimension.<br>
> Modification is required if you want to use other alternative servo.
> TowerPro MG92B can be found on Ebay seller [servohorns959](https://www.ebay.com/usr/servohorns959), which is listed on TowerPro official website ([Link] (http://www.towerpro.com.tw/about-us-2/)). <br>I also got mime servo from him.
### 3D-Printed Parts
#### Body x 1
| Filename | Thumbnail | Required |
| -------------- | ------------------------------------------- | -------- |
| body_top |  | 1 |
| body_bottom |  | 1 |
| body_center |  | 1 |
| body_side_wall |  | 2 |
| body_back_wall |  | 1 |
#### Leg x 6
| Filename | Thumbnail | Required |
| ------------ | --------------------------------------- | -------- |
| thigh_top |  | 1 (x6) |
| thigh_bottom |  | 1 (x6) |
| joint_cross |  | 1 (x6) |
| joint_top |  | 2 (x6) |
| joint_bottom |  | 2 (x6) |
| leg_top |  | 1 (x6) |
| let_bottom |  | 1 (x6) |
| foot_top |  | 1 (x6) |
| foot_bottom |  | 1 (x6) |
| foot_ground |  | 1 (x6) |
| foot_tip |  | 1 (x6) |
### Others
| Name | Spec | Thumbnail | Required | Note |
| --------- | ------- | ---------------------------- | -------- | ------------------------------------------------- |
| Screw | M2 6mm |  | 54 | Servo Arm: 1 x 18< br > Joint: 4 x 6< br > Thigh: 2 x 6 |
| Screw | M2 10mm |  | 24 | Thigh: 1 x 6< br > Pin lock: 1 x 18 |
| Screw | M2 30mm |  | 36 | Servo: 2 x 18 |
| Nuts | M2 |  | 36 | Servo: 2 x 18 |
| Pin (304) | M4 6mm |  | 18 | Servo: 1 x 18 |
### Leg Assemble
#### Leg Assemble Instruction
Leg assembly instruction video https://youtu.be/oaAE5fC09KQ is also available.
< a href = 'https://youtu.be/oaAE5fC09KQ' > < img src = 'http://img.youtube.com/vi/oaAE5fC09KQ/mqdefault.jpg' / > < / a >
##### Preparation
For one leg, you will need 3 MG92B servo and below printed parts
| Filename | Thumbnail | Required |
| ------------ | --------------------------------------- | -------- |
| thigh_top |  | 1 |
| thigh_bottom |  | 1 |
| joint_cross |  | 1 |
| joint_top |  | 2 |
| joint_bottom |  | 2 |
| leg_top |  | 1 |
| let_bottom |  | 1 |
| foot_top |  | 1 |
| foot_bottom |  | 1 |
| foot_ground |  | 1 |
| foot_tip |  | 1 |
##### Step 1
Combine `thigh_top` , `MG92B` and `thigh_bottom` , use M2x30mm screw and nut to secure them together.
##### Step 2
Grab one `joint_cross` , `joint_top` and `joint_bottom` and combine them
##### 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
##### Step 4
Grab `foot_top` , `foot_bottom` and `foot_ground` (and `foot_top` ) and assemble them.
##### Finish!
Great, you got 1 leg done, 5 more to go :)
Leg assembly instruction video https://youtu.be/oaAE5fC09KQ is also available.
< a href = 'https://youtu.be/oaAE5fC09KQ' > < img src = 'http://img.youtube.com/vi/oaAE5fC09KQ/mqdefault.jpg' / > < / a >
> Note. Total 6 Legs are required.
