Wind-powered compost tumbler with integrated sieve in Trommel fashion. Finished product falls through the bottom while unfinished stays inside until broken down sufficiently. This will be just one component in a larger system but ultimately will work as a standalone concept to be marketed to individuals, community gardens, or even municipalities. I do need sensors to monitor core temperature while in constant (very slow) motion and provide feedback to a watering system, as well as the mechanics of transmitting the mechanical power from the drive-shafts to the reactor and optionally adding a conveyor underneath, to collect the fines and feed a vermicompost system.
I started prototyping the Garden Mill today. I took my existing trommel sifter which normally mounts on top of my wheelbarrow and begun with it as the sieve.
I've had the gearbox for some time but needed to visualize how it was going to drive the rollers. I cut some wheels and pulleys out of scrap plywood (because shoestring budget) and ran them on to threaded rod for axles. I mounted the gearbox to an appropriate surface and had to kludge together a belt tensioner.
All was for naught though as at the end of the day, the single drive axle did not have enough traction to drive the drum.
Maybe I should have cut additional pulleys and put another belt on thus turning the idler axle into another drive axle. This still relies on the weight of the drum to provide the high coefficient of friction necessary to create traction between the plywood wheels and bicycle rims. Unless... damn. I just realized I could have cut some gears.
I'm presenting this idea to my local hackerspace on Wednesday and I want to have something tangible to show rather than just the sketchup file. I think tomorrow I'll see if I can't make some 24" diameter gears to wrap around the bicycle rims.