# CervicalBot Bill of Materials

This file lists the main purchased components required to assemble the CervicalBot robot.

> Note: links and availability may change. Verify compatibility, thread sizes, voltage ratings, and shipping availability before ordering.

## Components

| Qty | Item | Purpose | Link | Notes |
|---:|---|---|---|---|
| 6 | High-torque waterproof servo motors | Main Stewart platform actuation | [Open link](https://www.galaxus.ch/en/s5/product/powerhd-lw-15mg-rc-servos-17446309) | Use 6 identical servos for the platform. Check horn/spline compatibility with your servo lever design. |
| 1 | Raspberry Pi 5 Model B, 8 GB RAM | Main onboard controller / API host | [Open link](https://www.pi-shop.ch/raspberry-pi-5-8-gb) | Recommended for running the robot control interface, API, and optional higher-level scripts. |
| 1 | PWM 12-bit servo HAT / bonnet | Multi-channel PWM generation for the six servos | [Open link](https://www.pi-shop.ch/adafruit-16-channel-pwm-servo-bonnet-fuer-raspberry-pi) | 16-channel PWM board; only 6 channels are required for CervicalBot. |
| 1 | IMU unit | Motion feedback, orientation sensing, repeatability checks | [Open link](https://www.pi-shop.ch/adafruit-9-dof-absolute-orientation-imu-fusion-breakout-bno055) | Optional but recommended for logging orientation and improving motion validation. |
| 1 | Power supply, 12 V / 4 A / 48 W | Main DC input supply | [Open link](https://www.pi-shop.ch/ed-psu1204-dc-12v-4a-power-adapter-phoenix-style-terminal) | Feeds the DC-DC converters. Verify current headroom for the final servo load case. |
| 2 | DC-DC buck converters, 12 V input to 5 V output | Regulated 5 V rails for logic and servo power distribution | [Open link](https://www.galaxus.ch/en/s1/product/purecrea-xl4016-step-down-dc-dc-buck-converter-300w-power-component-electronics-modules-36169156) | Set and verify output voltage before connecting electronics. Consider separate rails for Raspberry Pi and servos. |
| 6 | Stainless steel 155 mm link rods | Six Stewart platform legs / linkage rods | [Open link](https://de.aliexpress.com/item/1005006294001522.html) | Confirm rod length and thread type before ordering. Length must match the CAD assembly. |
| 12 | M4 fisheye joints / rod-end bearings | Spherical joints at both ends of the six link rods | [Open link](https://de.aliexpress.com/item/1005006023528112.html) | Two joints per leg. Confirm M4 thread and compatibility with the rods. |
| TBD | Connecting screws, nuts, washers, and spacers | Mechanical assembly and mounting of rods, joints, servos, electronics, and printed parts | TBD | Define from the final CAD: likely M3/M4 socket-head screws, locknuts, washers, and spacers. Add exact lengths after assembly validation. |

## Electrical notes

- Set the DC-DC converters to the required output voltage before connecting the Raspberry Pi, PWM board, servos, or IMU.
- Use adequate wire gauge for servo power distribution.
- Consider separating logic power and servo power rails to reduce noise and voltage dips.
- Add a common ground between the Raspberry Pi, PWM board, servo supply, and sensors.

## Mechanical notes

- The 155 mm rods and M4 fisheye joints should be checked against the CAD before ordering.
- Connecting screw lengths should be finalized after the CAD package is frozen and the first assembly is validated.
- Use washers and locknuts/threadlocker where vibration or cyclic motion may loosen joints.
