Magnetic Tumbler

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Member name: Matt F

Member contact: Email, found via list.

Project name & pitch: Magnetic Tumbler. A toaster-sized tool for tumbling small parts, brass casings, jewelery, etc. I am building it for Protospace,

Storage location: Bay ?? / Cart

Project start date: 31 Aug, 2013

Final Deadline: 01 Nov, 2013


  • 02 Sept, 2013 - Test frame is done. Motor appears underpowered, will test with less friction. Added more magnets, will see if enough.
  • 12 Sept, 2013 - No progress.
  • 20 Sept, 2013 - Took to makerfaire, no progress.
  • 27 Sept, 2013 - No progress.
  • 09 Oct, 2013 - No progress. Laser required, still no laser.

Additional Details

A magnetic tumbler is basically a container with magnetic stainless pin shot and some water inside ("shot" meaning tumbling media), that swirls around in a metal tornado, cleaning, polishing and burnishing any small parts you put inside. Good for brass (cartridges?), jewelry, machined parts.

The science is pretty low tech. Below the container you have a motor & spinning plate with magnets on it. Then a thin acrylic sheet, and on top goes the container. There's no mixing apparatus inside the container; when the magnets below the vessel spin they take the nearby pin shot on a ride with them and drag the media across the pieces being tumbled, flagellating them at high speed. <-- Oooh, ahhh.

One the size we're building costs ~$2200. The guy in the video above says $150 to build his.

$150? Nope. I think we'll build it for $0. <-- Rough build plan if you like following concrete plans. I talked to this guy a few years ago, I don't think he really understood how magnets work (Magnets? How do they work?) so I'll improve a bit on his design.

I've built three 95% of the way in the past. Last time I built one my idea of machining was "jigsaw & hot glue". PS's resources can do better.


- Frame (junk wood/acrylic)
- Induction motor (Jorgen donated a few, + there are others)
- Plate (someone will fab)
- Magnets (how do they work?)
- Top deck (scrap acrylic)
- Bowl/bucket/octagonal container for enhanced tumbling (scrap acrylic or bucket)
- Power switch/cord/etc (lots)

All that leaves is the non-consumable pin media, which I have a source on for about 10% the cost of buying it from a normal supply place. And I have some to test with.

Oh, and the magnets will probably be hard drive magnets. Wes has a stack of dozens which I saw and is what reminded me of this. Wes plans on building one for himself, I think, or just the space, not sure. Either way, I can strip extras and it's not a lot of work to make one for the space.

Bonus Science:

Why use this instead of a traditional rotary/vibratory tumbler? A rotary tumbler is speed limited to gravity, you can't spin it faster or nothing actually falls and tumbles. Vibratory tumblers are loud and shake a room and are very slow. This is somewhere on the order of 10-100x faster than either of those because you can force the shrapnel tornado through the workpiece as fast as you can spin the motor.