RC F1 gear diff based on F104 components

thingiverse

Original posting: This is a diff for a Tamiya F104, might fit other Tamiya F1 cars as well. Up to now the right hand gear has proven too weak. https://www.youtube.com/watch?v=eY1WNWNQrKE 2020-01-20 I made an update of the right gear / hub combo, splitting it into two parts to the hub can be printed horizontally. The unit used to break between the hub and the gear. Not when racing, but when crashing. 2020-02-23 I made some updates to the star wheels, left gear and spur, nothing major. The revised right gear is not a success, it is to wobbly because of consisting to two parts. CA glueing it together helps but I don't like that as a solution. I designed a new one using a smaller inner bearing, 5x8x2,5 mm instead of 5x11x4. This leaves more material around the bearing at the point where it used to break. The new parts have been proven to fit and work, but I've not been out on the track with them, racing and crashing. Assembly is pretty straight forward. First, you need to check and clean all teeth of every gear with an exacto knife. Then assemble: - The left gear you need to clean up because it is printed with supports.After cleaning it, you just slide the gear onto the F104 shaft. - Next you need 3 little axles for the planet gears, I made those out of hardened 2 mm nails, about 9 mm long. Make sure the gears don't bind on them first. Next, without the gears, trail-fit them into the spur. They should go in and out smoothly and not block the bearing hole when in place. Once all parts fit individually, put it all together and lock the assembly by pressing in the centre bearing. Then just slide it onto the F104 gear, on top of the left gear. - Press the bigger bearing and the smaller bearing into the right gear. Slide the assembly on and lock it in place with a self locking M4 (nylock) nut, don't overtighten. There is not a stop, you need to tighten carefully untill it all meshes well and does not bind. - Lastly, fit the original F104 wheel carrying thingy with the original rod and grub screw. And you're done! In the photos you see I have a white right gear, kindly printed for me by a fellow RC and 3D print enthousiast. It is printed in Nylon. I will print some in PETG, too, as the new design should be stronger, but this is certainly nice to have this in Nylon. Printing: I printed everything at 40mm/s in 0,1 mm layers out of PETG. I printed the first prototypes out of PLA, and everything exept the right gear was OK in PLA. But that material seems to age rather quickly by attrackting moisture, so I switched to PETG on all RC car parts I make, and most other things too. The only part printed with supports is the left gear, the rest does not need it. BTW, the green and red cross sections in the picture show the first design and the second, with the diffenent smaller bearing. This should be an improvement.