It’s very likely that a majority of readers will have had a gear fail in a piece of equipment, causing it to be unrepairable. This is a problem particularly with plastic gears, which shed teeth faster than a child who has discovered the financial returns of the Tooth Fairy.
[BcastLar] has a shredder with a gear that has, well, shredded. He’s posted a video series over three parts that while ostensibly about fixing his shredder, is in reality a three-part tutorial on how to create custom gears using FreeCAD. While the principles of a gear are readily apparent to most observers their intricacies hide significant complexity which he does a great job of explaining. How to measure the parameters of a given gear, explaining mysteries such as pitch angle or beta, he breaks everything down in easy to understand steps.
His tool of choice is FreeCAD, and while he explains that FreeCAD has the ability to make gears from scratch the tool employed in the videos is the Gear Workbench plugin. He shows how this software removes the complexity of creating a gear, and shows the process on his screen as he creates the custom shredder part.
Finally, the process of 3D printing the gear is explained. You might ask why not machine it, to which he responds that tooling for non-standard gear profiles is prohibitively expensive. We’ve placed all three videos below the break, and we think you might want to make yourself a cup of tea or something and work through them.
Strain wave gearing is a clever way to produce a high-efficiency, high ratio gearbox within a small space. It involves an outer fixed ring of gear teeth and an inner flexible ring of teeth which are made to mesh with the outer by means of an oval rotor distorting the ring. They aren’t cheap, so [Leo Vu] has had a go at producing some 3D-printable strain wave gearboxes that you could use in your robotic projects.
He’s created his gearbox in three ratios, 1:31, 1:21 and 1:15. It’s not the most miniature of devices at 145mm in diameter and weighing well over a kilogram, but we can still imagine plenty of exciting applications for it. We’d be curious as to how tough a 3D printed gear can be, but we’d expect you’ll be interested in it for modest-sized robots rather than Formula One cars. There’s a video featuring the gearbox which we’ve placed below the break.
Exploring the mathematics behind everyone’s favourite unorientable single-sided surface can be quite the mind-bending exercise, so it’s nice that it’s so easy to make a Mobius strip out of paper and a single piece of tape. That demonstration was far from enough for [elmins]. who printed this Mobius strip of gears. The teeth fit together, and all the gears move, but there is still only one side and one edge (we think).
The idea to tackle the project came from seeing an animation of Mobius gears. Wondering if it would be possible to actually create such a thing, [elmins] got to work. The design is printed in 60 pieces, 30 each for the inner and outer parts. The entire assembly is printed in PETG, an unconventional choice but by no means unsuitable. 285 ball bearings help the rings rotate.
The gears use a standard involute bevel profile, though [elmins] suspects this could be an area of further optimisation. The parts were printed in an orientation to ensure the print lines run around the races, allowing for minimal finishing and smooth rolling of the bearings. This is a good study of just what can be achieved with some smart modelling and perseverance.
We’ve all seen word clocks, and they’re great, but there are only so many ways to show the time in words. This word clock with 114 servos is the hard way to do it.
We’re not sure what [Moritz v. Sivers] was aiming for with this projection clock, but he certainly got it right. The basic idea is to project the characters needed to compose the time messages onto a translucent PVC screen, which could certainly have been accomplished with just a simple character mask and some LEDs. But for extra effect, [Moritz] mounted each character to a letterbox mounted over a Neopixel. The letterboxes are attached to a rack and pinion driven by a micro servo. The closer they get to the screen, the sharper the focus and the smaller the size of the character. Add in a little color changing and the time appears to float out from a jumbled, unfocused background. It’s quite eye-catching, and worth the 200+ hours of printing time it took to make all the parts. Complete build instructions are available, and a demo video is after the break.
We like pretty much any word clock – big, small, or even widescreen. This one really pushes all our buttons, though.
You may think you’ve never heard of Greg Zumwalt, but if you’ve spent any time on Instructables or Thingiverse, chances are pretty good you’ve seen some of his work. After a long career that ranged from avionics design and programming to video game development, Greg retired and found himself with the time to pursue pet projects that had always been on the back burner, including his intricate 3D-printed automata. His motto is “I fail when I decide to stop learning,” and from the number of projects he turns out and the different methods he incorporates, he has no intention of failing.
You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Learning Through Play Hack Chat and we’ll put that in the queue for the Hack Chat discussion.
Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
There was a time, not so very long ago, when simply getting a 3D printer to squirt out an object that was roughly the intended shape and size of what the user saw on their computer screen was an accomplishment. But like every other technology, the state of the art has moved forward. Today the printers are better, and the software to drive them is more capable and intuitive. It was this evolution of desktop 3D printing that inspired the recently concluded 3D Printed Gears, Pulleys, and Cams contest. We wanted to see what hackers and makers can pull off with today’s 3D printing tools, and the community rose to the challenge.
Let’s take a look at the top ten spinning, walking, flapping, and cranking 3D printed designs that shook us up:
We find the nomenclature of these displays to be a bit confusing so let’s do a quick rundown. You may be most familiar with flip-dot displays, basically a dot-matrix grid of physical pixels that are black on one side and brightly colored (usually chartreuse) on the other. We saw a giant flip-dot display at CES four years ago. Akin to flip-dots are flip-segment displays which do the same thing but with segments of a digit rather than dots. We featured a 3D printed version of these last week. The common aspect of most flip displays is an electromagnet used to change the state of the dot or segment.
The version [Peter] designed gets rid of the magnets and coils, replacing them with mechanical logic instead. Each segment sits in a track on the frame of the digit. When slid to one position it is hidden by the bezel, in the other position it slides into view. A cleverly designed set of cams move the segments at each of 10 positions. The animated graphic here shows three cams which are responsible for moving just two of the segments. More cams are added to complete assembly, a process shown in the second half of the demo video found below.