115:1 3 stage planetary gearbox

thingiverse

Made as part of a collaborative group project in one of my classes.\r\n\r\nEach stage is roughly ~4.8:1, it's recommended to use 1/8" steel rods for axles and shafts and 1/8" square brass tubing was utilized for the square shafts. The output shaft was machined from brass but could be printed if desired. Each stage can be and was printed together in a single operation. The torque at the last stage is a bit high so it's recommended to replace the spider with a sheet metal one if possible.\r\n\r\nIn the included pdf, you'll find; an exploded view to help with assembly, dimensions for non-printed internal shafts, sample input and output shafts with all necessary dimensions to design your own, and dimensions for all mounting holes. \r\n\r\nThe gearbox was designed for use with 6-32 screws but could also utilize m3 or other similar sized threads. Four bolts and four nuts are required to hold the stages together, and the backplate should be glued to the rear ring gear. There are five holes for mounting the gearbox, two at the front and three at the back. To keep the output shaft in place, you will need to design a way to secure it if you don't mount a plate on the backplate and use the retaining ring to hold the shaft.\r\n\r\nDue to the modular design, it is possible to not use the middle stage for less of a reduction or multiple middle stages for a higher reduction. However, if using a total of four or more stages are used, metal spiders will be required for all stages past the first two-three or else the square output hole will strip. I have not tested using a total of five stages but there may be a risk of gears skipping or jamming under high loads.