Harmonic Drive (Nema 23) 3D-printable

thingiverse

For my final exams, I'm designing and assembling a 6-axis robotic arm in the style of the UR robot arms ("universal robots"). Since original harmonic drive gearings are too costly for me (one costs about $675), I'm attempting to create my own version. I'm utilizing 6mm steel softair BBs as flexible bearings inside the gearing. I've already printed an approximate model of the gearing, which functions (hand-driven). However, this project remains a work in progress and I will add everything over the next few days. UPDATE: I have built a first prototype (check the photo), but didn't like how the bearings performed – they weren't precise enough to meet my quality standards. Therefore, I redesigned the mounting cylinder, enclosure, and bearings. First, I tried to secure the inner rings of the bearings with a thread on the mounting cylinder which didn't work either, at least not when printing with an 0.8mm nozzle. In order to press the inner rings of the bearings onto the mounting cylinder, I'm now using the same holes that I use to transfer radial forces from the mounting cylinder to the flexspline. Also, I updated all other files here on thingiverse. OLD UPDATE: I updated the following Files: "Mounting Cage Flex Bearing," "Mounting Cage Angular Bearing," "Enclosure," and "Motor Holder." OLD UPDATE: I now have a more detailed version of the gearing that's compatible with Nema 23 motors. I will now test if everything works out but it takes some time to print... OLD UPDATE: My Nema 17 Motor isn't powerful enough to drive the gearing yet. I will check if a Nema 23 Motor which is compatible with the ustepper motor driver or Radds motor driver, delivers sufficient power. Otherwise, I will add a planetary gearing on top of the Nema 23 or go with another motor driver.