If you’re reading Hackaday, there’s a good chance you had a rock tumbler in your younger days. Hell, we’d put odds on a few of you having one rumbling away in the background as you read this. They’re relatively simple contraptions, and a common enough DIY project. But even still, this largely 3D printed rock tumbler from [Fraens] is unique enough to stand out.
To make a basic rock tumbler, all you really need to do is rotate a cylindrical chamber and let physics do its thing. Such contraptions are known as, unsurprisingly, rotary rock tumblers. But what [Fraens] has put together here is a vibratory tumbler, which…well, it vibrates. If this was Rockaday we might go farther down this particular rabbit hole and explain the pros and cons of each machine, but the short version is that vibratory tumblers are more mechanically complex and are generally better suited to fine finish work than rotary tumblers which take a brute force approach that tends to round off the rocks.
Anyway, while you could use a motor with an offset weight to generate the necessary vibrations, [Fraens] decided to go with a similar electromagnet arrangement to what he used in the vibratory bowl feeder he built last year. Pulsing the electromagnet pulls down the large 3D printed spring, which imparts not only the vertical motion you’d expect, but a touch of horizontal as well.
The end result is a “tossing” motion that gets the rocks inside the printed chamber moving around nicely. The motion can be fine tuned by adjusti ..
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