Mineral Tumbler: An eye-baller’s guide.


Here is a simple guide to making an extremely simple ball mill. The point of this project is to create small amounts of powdered metal and charcoal. It is not meant to make Kgs worth of ground material, and although it is possible to tumble and shine rocks, there is going to be a very low limit to the weight this particular build can handle. That said, it does offer 2 major advantages. The first being that it’s compact (not exactly the definition of light, but it is portable) and the second being simplicity (most of these measurements are there only to be a rough guide,as most of them were decided on the spot rather than following a set plan).

Disclaimer: this is a mix pot of some of the materials just lying around my workshop. If you want a mineral tumbler (or a ball mill, the two are basically the same thing) and are planning to buy the parts you need, then this may not be the best approach. I recommend you do some research on what acceptable components are.

The materials used:



  • A windshield wiper motor (I have no idea how standard these motors are. Good luck.)
  • Wood plank, approximately 2cm thick(The two pieces I used were: 20cm x 11cm and 13cm x 11cm)
  • Wood screws of the appropriate length
  • Thread bar and nuts (5mm)
  • PVC pipe (110mm)
  • Two threaded access caps
  • Plain end cap
  • Washers
  • PVC glue
  • General tools
  • Drill
  • Saw (In my case, a drop saw)
  • Drill bits (Have a couple of sizes handy)
  • 90° straight edge & pencil

The design relies on the ability of the motor to carry the weight of the material in the chamber. A windshield wiper motor is designed to give out a large amount of torque at the expense of speed. The slower the drum turns, the less heat will be generated over time, so this is somewhat of a safety feature The motor also encases a large gear (obviously, to gear down the motor’s actual speed) which is attached to the drive shaft. The way they are connected allows the shaft to *somewhat* negate the effect ofweight on the motor itself (something that is not true to the same extent for other solenoid motors).