3D printers are good for a lot of things, but making parts for power transmission doesn’t seem to be one of them. Oh sure, some light-duty gears and timing belt sprockets will work just fine when printed, but oftentimes squooshed plastic parts are just too compliant for serious power transmission use.
But that’s not a hard and fast rule. In fact, this 3D-printed strain-wave transmission relies on the flexibility of printed parts to work its torque amplification magic. In case you haven’t been briefed, strain-wave gearing uses a flexible externally toothed spline nested inside an internally toothed stationary gear. Inside the flexible spline is a wave generator, which is just a symmetrical cam that deforms the spline so that it engages with the outside gear. The result is a high ratio gear train that really beefs up the torque applied to the wave generator.
It took a couple of prototypes for [Brian Bocken] to dial in his version of the strain-wave drive. The PLA he used for the flexible spline worked, but wasn’t going to be good for the long haul. A second version using TPU proved better, but improvements to the motor mount were needed. The final version proved to pack a punch in the torque department, enough to move a car. Check it out in the video below.
Strain-wave gears have a lot of applications, especially in robotic arms and legs — very compact versions with the motor built right in would be great here. If you’re having trouble visualizing how they work, maybe a Lego version will clear things up.
Using the wrong material for the task is no excuse. How about some articles not exclusively related to PLA, PETG and TPU?
Most people don’t end up using fancy materials – case in point this maker didn’t. Would you have them ignore this make because of the materials?
Not everyone has access to exotic materials and the 3d printers to use them.
You might as well be asking why there are not articles about off the shelf solutions instead of DIY versions.
Using a cheap and simple to use material is the correct process for prototyping
One word.
Prototyping.
Lots of good progress has been made recently in 3D printed technical parts. Even if they can’t compete specs-wise with their metal counterparts, they do have the advantage of being cheap and easily customized. I hope they will be used in the future to make entire 3D printed machines.