EMC2 Gen 2 - Zero-Backlash Herringbone Planetary (66:1)

thingiverse

Videos hosted on our zeronet platform: https://ngnoid.tv/?Channel=quantumkitty@zeroid.bit And check out our zeronet STL repo: https://3d.ngnoid.tv/ Zero-backlash herringbone planetary gearbox (quasi-harmonic drive). 66:1 (Includes AS5600 encoder holder for closed-loop control. Use 25mm m3 screws to mount. Use the magnet holder ring to stop it from slipping from the shaft! Sand it slightly if it gets stuck around the edges.) *Added skewed magnet washer/holder to enable the use of standard neodymium magnets for the AS5600! (Diametrically polarised magnets still recommended). Print it with -0.1mm horizontal expansion for better fit. Uses slightly undersized flex gears in order to keep the planet gears in place. The flex is very subtle and barely noticeable which is what we need in order to preserve the lifespan of the ring gears and avoid excessive friction. Best printed in PETG. A lot of people have for some reason advised against this but I personally haven't found any issues, as long as these are lubricated (silicone or lithium grease). PETG has better layer adhesion and flexibility than ABS and PLA which makes it perfect for this. Nylon would also be a good option but it's a real pain to print with and not very practical on most printers. All gears are ready to print at 100% scale with no hidden additional print settings. Note: You can try various degrees of flex using the 99% and 99.5% scale with -0.1 horizontal expansion to better tune the gearbox. Make sure you're not printing too close to the heatbed.. as this can create an elephant foot that produces excessive friction. Too small of a ring gear, and you'll introduce friction and losses for the motor. Too big of a ring gear, and you'll reintroduce backlash. The original setting is still the one I've found works best! Requires 4x 22mm m3 screws, 4x 25mm m3 screws and 4x m3 nuts. And then some 4.5mm steel balls for the bearings. (You can use a crimping tool to cut m3 screws!) Compatible with Sylvie 2021 humanoid robot. Compatible with EMC2 Gen 1 Size A gearbox body (as long as 1mm spacer is used to stop the bearing from squashing the gears!) The aim with the EMC2 gearboxes is to make robotics affordable for once. The gears are designed in such a way so as to make them pretty easy to replace but also very durable. You should be able to get months of operation out of these and if something goes wrong, or if you want to change the gear ratio.. simply swap out the planet and ring gears (for a few cents each) without having to print everything from scratch!