A wind-powered rock tumbler

In this project we wanted to use the energy of the wind to rotate a barrel filled with stones, water and grit in order to polish the stones.

We built a wind turbine that powered the rotation of the barrel through the use of a couple of cog wheels. The ball bearings for the turbine were commercially sourced and we used bearings from old magnetic tapes for the mechanism inside the nacelle.

Description of the device

wind turbine and rock tumbler

The general structure

We placed the device in an open area, on the top of a pergola.

The (vertical) axis of the turbine extends below the pergola, inside a nacelle, where it powers the rotation of a cylinder, on top of which rests a barrel.

wind turbine on the top of a pergola

The turbine
The blades are sections of half round plastic gutters inserted inside semi-circular slots cut into two plywood disks.

The axis of the turbine is supported, at its top and under the bottom disk, by ball bearings that allow a rotation with very little friction.

cog wheels powering the rotation of a barrel

The cog wheels
The axis of the turbine and that of the cylinder spinning the barrel are perpendicular. A couple of cog wheels allow the transmission of the movement. Those were cut out from a wooden plank.

rock tumbler inside the nacelle under a wind turbine

Inside the nacelle, the barrel rests on top of the rotating cylinder, and at the back against two ball bearings.

The content of the barrel being quite heavy, it was necessary to wrap the container with a piece of anti-slip mat to ensure a good contact.

rocks partially polished inside a tumbler


The system worked and the stones definitely started to get polished. It is however a long process which, unfortunately, we could not complete before we dismantled the mechanism and moved home.

We found that the sight of the device able to operate without supervision and with free energy very satisfying.  

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