3D-Printed Strain Wave Gear Needs Your Help

In most mechanical systems, metal gears that bend are a bad thing. But not so for strain wave gearing, which is designed to take advantage of a metal gear flexing to achieve an action much like planetary gears. The fun isn’t limited to metal anymore, though, if you 3D print a strain wave gear like this.

Strain-wave gearing is nothing new – it was invented in 1957 and has traveled to the moon on the lunar rover. And you may recall [Kristine Panos]’ recent article on a LEGO strain wave gear, which makes it easy to visualize how they work. She also has a great description of how the flex spline, wave generator, and circular spline interact, so we’ll spare those details here. [Simon Merret]’s interpretation of the strain wave gear is very simple and similar to other 3D-printed versions, except that he uses an inside-out timing belt as the flex spline. The wave generator is just an arm with a roller bearing at each end, and despite needing a few tweaks the gear does an admirable job.

Simon is reaching out for help in getting this gear ready for use where the industrial versions see frequent application – the first and second degrees of freedom of robotic arms. If you’ve got any ideas, head over to his project page on Hackaday.io and pitch in.

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Mostly Wood Motorized Camera Slider

Camera slides can make for interesting dolly shots in your videos, or can spice up an otherwise drab time-lapse sequence. When it came time for one of his own, [Bob] did what any hacker would do and rolled his own motorized camera slide in the wood shop.

We always like to see work based on a hacker’s own prior art, and [Bob] managed to leverage parts and techniques from his impromptu claw machine build for this slider. The rollers in this project use the same 3/4″ angle aluminum and skateboard bearings as the previous build. The bearings roll on a plywood strip capped with the same angle stock for durability and low friction. The stepper motor bracket and pillow blocks are 3D printed, as are the timing pulleys. [Bob] admits that the whole rig is a little noisy and blames it on the rough quality of the pulley prints. He has plans to replace them with commercially available pulleys, which should help; one further suggestion we have is to code a soft-start algorithm into the ATtiny85 to eliminate that jerkiness you see when he demos the slider in the video below.

There are plenty of ways to move a camera along a single axis, and a surprising number of them use parts from the roller sports. We’ve covered quite a few of them before, like this slide that uses skateboard trucks, or this non-motorized rig built from fence posts and inline skate wheels.

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Converting a manual camera lens to use motorized zoom and focus

[Guy] wrote in to share this motorized camera lens project he recently finished. He really loved the zoom lens, but since both zoom and focus are manually controlled, he sometimes had trouble getting both set to the right place in time to take the shot. With modern DSLR cameras which allow video capture, he also wants to have the option of a smooth zoom that is always in focus. The solution was to add motors to the rings and control them with a Wii classic controller.

This hack really shines when it comes to the add-on hardware. He has some beautifully made rings which wrap around the focus and zoom rings on the lens. They are then held in place by a timing belt. These belts have teeth which key into the gears on a pair of servo motors. From there it’s a snap to drive the motors with an Arduino, connecting to the Wii controller with a breakout connector. You can see [Guy] showing off the build in the clip after the break.

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