Donkey Car Dog Bone

thingiverse

Human: On both the Desert Monster and Magnet RC cars, the Dog Bones frequently fall out. This is an attempt to replace them with 3D prints that don't get lost as often. Designed for printing in PET with 3-4 walls, 50% infill, and a 0.4mm nozzle. 1.5mm piano wire was cut down to ~8mm length for the pins at the end of the Dog Bones. These holes are super snug and will need to be tapped into place with a hammer. The part is designed to fit snugly, so some sanding may be needed, especially at the ball ends. As it wears out, the part will loosen. Due to this, I don't recommend shrinking the part for a better early fit. These printed Dog Bones aren't as low-friction as the original metal ones, so if you have one side with a metal Dog Bone and the other with a printed one, the slip differential will take the path of least resistance. It's best to replace both sides of the same axle at once. The pins at the ends are in parallel due to print grain. I don't recommend turning the hole horizontal because that would put the shear load on the grain and part failure is likely. If you want to reduce friction by having the ball-end pins perpendicular, try heating the Dog Bone with a hot air gun and then carefully twisting it over its entire length.