Are your aluminum extrusions too straight? The Crimson Axlef*cker can help you out. It’s a remarkable 3D printed, 4-stage, 125:1 reduction gearbox driven by a brushless motor. Designer [jlittle988] decided to test an early prototype to destruction and while he was expecting something to break, he didn’t expect it to twist the 2020 aluminum extrusion shaft before it did. We suppose the name kind of stuck after that.
[jlittle988] has been documenting the build progress on reddit, and recently posted a fascinating video (embedded below) of the revised gearbox twisting the output shaft even further. He’s a bit coy about the big picture, saying only that the unit is part of a larger project. In fact, despite the showy tests, his goal is not to simply obtain maximum torque. We can only speculate on what his bigger project is, but in the meantime, seeing the gearbox results is some good clean fun. He first announced the gearbox test results here, and swiftly followed it up with some revisions, then the aforementioned video. There’s also an image gallery of the internals, so check that out.
The Crimson Axlef*cker is driven by an ODrive brushless dual-shaft motor and an ODrive controller as well; that’s the same ODrive whose open source motor controller design impressed us so much in the past.
Between projects like this one and other gearboxes like this cycloidal drive, it’s clear that custom gearbox design is yet another door that 3D printing has thrown wide open, allowing hobbyists to push developments that wouldn’t have been feasible even just a few years earlier.
Continue reading “Behold The Crimson Axlef*cker (Do Not Insert Finger)”
Researchers from the University of Sussex used 3D printing for a modular approach to acoustic lens design. 16 different pre-printed “bricks” (shown here) can be assembled in various combinations to get different results. There are limitations, however. The demonstration lenses only work in a narrow bandwidth, meaning that the sound they work with is limited to about an octave at best. That’s enough for a simple melody, but not nearly enough to cover a human’s full audible range. 
The payload container is a hollow tube with a 3D printed threaded adaptor attached to one end. Payload goes into the tube, and the tube inserts into a hole in the bulkhead, screwing down securely. The result is an easy way to send up something like a GPS tracker, possibly with a LoRa module attached to it. That combination is a popular one with high-altitude balloons, which, like rockets, also require people to retrieve them after not-entirely-predictable landings. LoRa wireless communications have very long range, but that doesn’t help if there’s an obstruction like a hill between you and the transmitter. In those cases, 
The entire mechanism including the spring is 3D printed, but the spring is PETG and the rest is PLA. [u407] doubts PLA would work for the spring because of how much it gets compressed, but suggests that ABS might work as an alternative.
The basic idea is that a 3D print is started, then paused after a few layers. A fine fabric mesh (like tulle, commonly used for bridal veils) is then stretched taut across the print bed, and printing is resumed. If all goes well, the result is 3D printed elements embedded into a flexible, wearable sheet.
Now, for us at least, fantasy became a reality as [Peterthinks] makes public his 
The device works by manually flicking the spring (rubber band) loaded side switch which then toggles the picking tang up and down whilst simultaneously using another tang to gently prime the opening rotator.
