by cfleis1, published
This is a wind up toy using all simple parts that can be produced on a 3D printer. The spring and stop may need some experimenting with, but the mechanics and concept are simple and reliable.
I think the gears and spring mechanisms do a great job of demonstrating the capabilities of 3D printers and the out-of-the-box mentality the MakerBot giveaway is encouraging.
Just print up the parts and assemble in accordance with the part call-out image. For the axles, use 3/8" D-profile shaft (mcmaster.com part # 8632T2) then use several 3/8" shaft collars (mcmaster part # 6435K13) to hold the shafts and wheels at the correct alignment positions. For the pin that hold the Latch ,Stop and Spring in location use 1/8" dowel pins (mcmaster part # 98381A476).
To keep the rotating parts turning with relatively low friction, nylon washers can be used to separate the flush surfaces (mcmaster part # 90295A471).
To keep the Stop and Latch located over the Ratchet, 1/8" ID x 1/4" Long spacers are required (mcmaster part # 94639A332).
Make sure the Latch is flipped away from the vehicles body. Turn the wheels on the left side of the main image, counter clock-wise as shown. This will wind up the coil spring. Then flip the inward and let the vehicle take-off!