While visitng from Germany, my nephew wanted me to print something for him to play with using my Lulzbot AO-100 3D printer. Naturally I went straight to Thingiverse and found a cool Balloon Powered Jet Car that I could print up in about two hours with everything on a single plate. The video below is a timelapse of the print which was sped up about 1500%.
I sliced the model at a .40 layer height, 25% infill, and speeds were around 70mm/sec on Peremiters, Small Peremiters, and Infill. With such a thick print, I decided to squish the first layer a little more than normal. I chose 70% over the usual 90%. This turned out to be an issue with the wheels as it made one side of the wheels a little wider than the other 99%. A quick sanding took care of this though.
I used finishing nails to mount the wheels and used a drill bit to clean up the car axel holes, then a slightly larger drill bit to open up the wheel axel holes a little. Unfortunately the balloons I had on hand were just not powerful enough to push the car across the floor. Still, my nephew had a blast watching the car form infront of his eyes. I honestly think that he sat and watch the entire print.
Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.
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One reason why the balloon power is insufficient is the exaust is effectivly a straight pipe — which means the speed (or lack thereof) of the car scales directly with the pressure in the balloon. Changing the exaust pipe to a De Laval nozzle (https://en.wikipedia.org/wiki/De_Laval_nozzle) would help a little (such nozzles work best with heated and pressurized streams of gas; but pressurized ambient temperature streams of gas still see some benefit).