Little Prints

This was a project to create components which would allow LittleBits circuitry toys to interface with the BluePrints mechanical toy system created by Sphero. The goal was to allow LittleBits motors and microcontrollers to drive contraptions built with BluePrints parts.

This project came about during my time working at the technology education non-profit PrairieSTEM after we met with representatives from Sphero to discuss BluePrints, the new mechanical toy system they were developing. I was very interested in BluePrints, as it seemed like a flexible system for making intersting mechanisms. For example, within a week I was able to create a functioning clock with multiple hands using only the base BluePrints pieces.

I was very interested in adding motorization to the BluePrint system. Our organization had previously taught lessons using "LittleBits" citcuitry toys which were also property of Sphero. The LittleBits system, in addition to having DC motors, provides access to circuitry such as lights, light sensors, buttons, and even programming through the "MicroBits" microcontroller. However, there were many challenges in adapting the two systems to interface with one another. First of all, BluePrints is based around a metric system, with blocks being intervals of 25mm. In contrast, the grids that hold the LittleBits elements are based on inches. This meant that all of the parts created to connect the two systems would have to account for this discrepancy. The axles used by the two systems were also incongruous, thus an adapter would have to be designed to allow the LittleBits motors to drive BluePrints gears.

I began by 3D printing a handful of test parts to find a way to interface with the LittleBits system. The system uses a grid of holes as a base with each circuitry component having small pegs which friction-fit into the holes. I dialed in a design for my own pegs which could be 3D printed, as well as finding proper hole dimensions for my own printed parts. This was more complicated than simply using calipers as the 3D printer cannot print perfect tolerances from measurement.

Once I had finished finding proper dimensions for the LittleBits connections, I used the CAD files for BluePrints to design the adapters for my system. I was very happy to find that Sphero had made public CAD files for each and every part in their BluePrints system. I designed motor mounts, axle adapters, and parts to mounts LittleBits plates onto BluePrints trusses all in Fusion 360.

One of the earliest obstacles of the project was printing the complicated geometry for the BluePrints clips (pictured above). It was possible to print this part flat on the build plate with no support material, however the part would be extremely fragile. This is because when the clip would be attached to a BluePrints truss, the flanges would be subjected to high lateral forces. Because of the orientation the clip was printed in, the flanges would sheer off along the plastic layer lines left by the printing process. To address this, I made the choice to split the clip in half in order to print the flanges in an orientation where the layers would be stronger against sheer forces.

Printing the clip like this fixed the strength issue, but introduced more work in the fabrication of each clip as the halves would have to be sanded before they could be glued into a whole clip. If I were to make this project again, I would investigate other ways of printing these clips which could get me the required strength with less processing after printing.

After solving the issue with the clips, the motor mount was fairly simple to design.

The motor mount (pictured above) utilizes two of the clips to connect to a BluePrints truss. These would be glued onto the bottom after printing the motor mount.

Creating the parts to connect LittleBits plates to BluePrints trusses ended up being more confusing than difficult. Because of the discrepancy in measurement systems used by the two toys, lining up these connectors to cleanly connect to both was very difficult. The solution I settled on was to have two versions of the connector which would be placed in opposite corners of the LittleBits plate to account for the offsets.

Pictured below is an example of the parts I developed being used in conjucnction with part from both systems to motorize a wheelbase.