Chilicorn Rail

We have a bunch of people around Markku and the unnamed second car. All of them are the kind of people who tend to get excited easily. This combined with our FutuLabs and Spice Program sometimes make the right things happen. This time we ended up creating a modular electronics mount system for the Robocar community. And now we’re ready to share our designs. And it’s all open source!

Our Markku is a 1:10 RC drifter. The original Donkeycar is 1:16. At first we made all these custom designed mounts for Raspberry, camera etc for our car. Those worked out nicely, but were pretty difficult to assemble and replace when something broke. We decided to make the next generation and this time do it properly. To be honest, neither the first generation of our design or the original Donkeycar really pleased our eyes as much as the new system.

This new system can be adapted to a new 1:10 model by working with only the adapter parts. Initially there will be adapters available for Tamiya TT-02 on-road version. We have also plans to get the adapters done for the offroad version and the “standard” 1:16 Donkeycar model.

If you have another model or improvement ideas, some design skills and maybe even access to a 3D-printer, feel free to modify and share your designs.

All files for the system can be found in the repository. Keep reading for instructions and models.

PrintingPrinting in progress with TAZ 6

Instructions

First you need to print the parts. Our primary material choice has been Colorfabb HT, but nylon could work better for the rail, camera and powerbank mounts, since by our experience they break most easily. Other mounts will probably work just fine with any material like PLA.

You’ll need a printer with big enough bed for the 30cm long rail. We are using a LulzBot TAZ 6 ourselves. There are some plans for a rail that could be assembled from shorter parts, but we’ll see if those realize. All the models are designed in a way that you shouldn’t need supports in your slicer settings.

After you have all the parts you need printed, you need to assemble all the parts together. All the mounts are attached to the rail with M3 bolts and nuts, preferably M3x20 Torx. When the rail is assembled with the mounts, the adapters are attached to the rail and finally the whole setup is attached to the car. Installing the electronics to the mounts may be easier before coupling them into the rail, but can be done also after.

You will probably want to print also some spares for those nasty crashes. The camera mount is the most important one and it’s taking the direct hit first, so could be a good idea to have a few of those.

Assembly for TT-02 mounts takes 10 minutes

Rail and adapters

Rail

The rail is a base for the whole system. It is 30cm long and has 3.5mm holes with 10mm spacing. The heart of the rail is a bar with square 6mm profile between 2mm gaps. There are indentations for M3 nuts and bolts. Rail is attached to the car with model specific adapters. The rail size is currently fixed, but we’re planning to release another parametrized version for different configuration needs.

Adapters

Adapters are for fitting the rail to different car models. At first we’re releasing the adapters for Tamiya TT-02 on-road model. These consist of a bracket and pins designed to fit directly to the mounting points of the body shell mounts. Hopefully we are able to gather new adapters for other models in the future. We’re already waiting for our standard 1:16 Donkeycar model to arrive so we can design and share the adapters.

PrintingFull set mounted on Tamiya TT-02 with adapters

Modules

There are a bunch of parts that you may or may not need in your configuration. Here are all the current parts in our library.

Camera mount

The camera mount is our guess on camera position. It’s designed for a Raspberry Pi wide-angle camera. The camera angle is 15 degrees down from the vertical axis. It’s 17 cm from the ground in our TT-02 model. In the potential future version it might be customizable both in angle and height. Holes for the camera are for the narrow 25 x 24 mm version.

Raspberry Pi Mount

Mount for Raspberry Pi 3B+ is built from the actual mount and the riser between the Raspberry and the mount.

Servo Shield

Servo shield mount for PCA9685.

Anker E1 Battery holder

Anker E1 battery mount with a mounting pin.

GY-521 IMU mount

Mount for acceleration sensor.