This was the first miniature vehicle I made. It is fully printed and somehow possible on FDM, with an 0.2mm nozzle. The chassis and gearbox took a few attempts to find the right fit, and the print-in-place steering is really pushing the limit of what FDM can do, but it all works and the finished van is barely larger than a bottle of Testor’s paint. This build uses a 1S lipo cell with not much more than 1C output, but that is enough for the 6mm motor with gearing. Because the entire van is printed and very light weight, that motor has plenty of power and can even spin out.
The steering uses a regular servo mounted vertically, using the horn to move the printed rack. That performs better than the linear servos I have, with much less jitter. There is a little bit of suspension on the front with a piece of spring between the steering rack assembly and chassis, held in place by the mounting pins. Most of the pins on this were made from pieces of jumbo paperclip, but the front wheels needed something thinner, so I used some cut off component leads.
The gearbox uses an intermediate gear between the pinion and final drive, with the final gear integrated into the back wheel. The pinion was originally too long for the chassis and had to be cut to length. Both back wheels are fixed onto the axle, and at this weight, that is enough to provide pretty even rear-wheel drive. The wheels work much better wrapped in a piece of heat shrink passing for a tire, although the hard plastic is great for drifting.
The wiring harness includes a power switch and charging port, but they did not really fit on the underside. I would like to do a second version of the van body that integrates them into the back windows or something. With some poking and prodding, you can flip the switch, but this version requires removing the body to charge the van.
The finished build is the size of a .25oz paint bottle and smaller in most dimensions than a Trumpeter S-65 tractor model that I was working on at the same time. Thumb also provided for scale.
Detailed build instructions and 3D printed parts can be found at: