3D Printed Parts
B.O.M (Bill of Materials)
Electronics
Assembly
Yertle can be 3D printed with PLA or ABS. You will need a printer with a build plate 150x150cm. It took me roughly 2 weeks (5-10 hours a day) to print all the parts on my Ender 3 Pro. Most of the parts are compatible with the original SpotMicro parts.
| Item | Quantity | Link | Notes |
|---|---|---|---|
| Top Shell | 1 | link | print in secondary colour |
| Bottom Shell | 1 | link | print in secondary colour |
| Front Shell | 1 | link | print in secondary colour |
| Back Shell | 1 | link | print in secondary colour |
| Item | Quantity | Link | Notes |
|---|---|---|---|
| Inner Shoulder Frame | 2 | link | no supports |
| Outer Shoulder Frame | 2 | link | no supports |
| Upper Shoulder Frame | 2 | link | no supports |
| Lower Shoulder Frame | 2 | link | no supports |
| Left Servo Mount | 2 | link | no supports |
| Right Servo Mount | 2 | link | no supports |
| Servo Mount Top Bracket | 4 | link | no supports |
| Side Body beam | 2 | link | no supports |
| Electronics Mounting Plate | 1 | link | no supports |
| Item | Quantity | Link | Notes |
|---|---|---|---|
| Inner Tibia | 4 | link | |
| Outer Tibia | 4 | link | |
| Femur | 4 | link | |
| Femur Servo Connector | 4 | link | high infill |
| Left Shoulder | 2 | link | print in secondary colour |
| Right Shoulder | 2 | link | print in secondary colour |
| Short Link | 4 | link | |
| Long Link | 4 | link |
| Item | Quantity | Cost | Link | Notes |
|---|---|---|---|---|
| PLA | 1Kg | £19 | -- | This can be ABS of PEG. |
| SPT Servo SPT5435LV-180W 35KG | 12 | £162.36 | link | They need to be >= 15Kg/cm. |
| M3 Screws, Nuts and washers | x100 | £10 | link | |
| MPU9250 | 1 | £5 | link | optional, you can use a different IMU if needed |
| ESP32s | 1 | £5 | link | |
| (Raspberry Pi 4B) | 1 | £50 | link | This is optional, The robot can uses remote device. |
| PCA9685 Servo Driver | 1 | £4 | link | |
| 7.4V 2S 5000mAh 50C LiPo Battery | 1 | £30 | link | this can be smaller if you want less weight/cost |
| SBEC 6V 20A | 1 | £20 | link | |
| Miniature Ball Bearings 5x16x5mm | 4 | £3 | link | |
| Deep Groove Ball Bearings 25x37x7mm | 4 | £9 | link | |
| RS PRO Miniature Ball Bearing 3x13X5mm | 8 | £9 | link | |
| 25T Metal Servo Circular Horn | 4 | £5 | link | |
| 25T Metal Servo Arm Horn | 4 | £5 | link | |
| Sleeve Bearing 3mm Bore x 5mm OD x 5mm | 32 | £15 | link |
Yertle is controlled by an ESP-32s microcontroller and a Raspberry Pi 4 Single board computer. The robot can operate with just the ESP but will require a computer or phone with WiFi capable of running python3. The flow diagram shows the general electronic connections and wiring. The current and voltage sensors are optional.
Connect and wire electronics to the mounting plate. You can use cable ties to hold the SBEC and battery. I normally connect the esp on top of the pi by soldering a custom Pi hat board that also mounts the IMU.
Construct the frame with inner servos and electronics.
Construct the legs.
Connect electronics and zero the servos (before connecting legs).
Connect legs and Shell.
