Week 4
3D printing
my goal for the week is to 3D print a wind up toy car.I was inspired by the idea of printing two pieces interlocking. My initial thought was I could recreate a pullback car with gears and stuff but that seemed a little ambitious. I decided to simplify it a little and use a rubber band wind up mechanism instead, but if I have extra time I'll try to make it more complex. I did a little googling and found this youtube video which I used roughly as inspiration. But rather than assembling pieces as seen in the video I designed it to be all printed in one go.
pieces separately and together
the idea is that a rubber band hooks over the peg in the front, then wraps around the axel in the back. As you wind the back wheel, you add elastic potential energy and when you set it down and release it the car should be propelled forward by unwinding.
I anticipate a small challenge in 3D printing because the design itself is not that supported so I will probably need to add supports or perhaps find an interesting orientation to print it.
In the prusa slicer I looked at what the print would look like if I just tried painting on the supports but no matter how I did it, it seemed likely that I would accidentally leave something unsupported and wind up with a ball of plastic so I added supports everywhere. I also chose to print the car on its side so that the rounded top would look smooth. I forgot to take a picture of the slice, but I took some photos throughout the support removing process. Getting the supports out between the wheels and the car body was a little challenging but with the combination of a knife and pliers I got them out.
From there the car looked as I intended it. The next goal was to get the car to be rubber band powered. The mechanism I had intended with a peg around one axle and a peg on the front of the car worked and the back wheel spun.
The issue was that the wheels didn't have enough friction to make the car move, so I added rubber bands to them. There still was an issue since the car was too light and would flip if wound up too much but I managed to get it to work ok-ish.