Designing an Open Source Hammer Mill

One of the machines listed in the Global VillageConstruction Set (GVCS) on the Open Source Ecology website is the hammermill/shedder. This machine is to be used to reduce the size of biomass passed through it. This may be anything from wood scraps left over from construction to corn stalks left over after harvesting that will be used as cattle feed. It can also be used to mill grain or shred yard waste. Large hammer mills can be used to shred entire tree stumps, concrete or rock.

The basic design of a hammer mill uses sets of metal hammer that spin around an axel. Small units usually operate at high speeds whereas large units usually operate at low speeds.  The axel(s) are placed in a case with an opening to allow material in, and an opening with a screen over it to allow only materials of sufficiently small size to exit. The material being fed into the mill is smashed by the spinning hammers which render it down to a size small enough to pass through the screen and fall down into a container or onto a conveyer belt or the ground. Some specialty high speed mills are able to smash minerals and rocks, while the majority of hammer mills are used on organic materials.

The hammer mill I am designing is small and of fairly common design. These preliminary drawings have been done so I could better understand all the parts that make up the mill. Not all of the parts are named correctly as of yet. I need to look over an existing mill schematic to get all the names down right.

I still have to reference existing mills to find out the average thicknesses and sizes of the steel used. I would like to mill to be about 1.5-2 feet in diameter and would use an electric motor to power it.

The interchangeable power source in the GVCS is called a Power Cube. It is a gas engine coupled to hydraulic pumps that provides power through pressurized hydraulic fluid. In this respect it is likely that a hammer mill in the GVCS would have to able to use a hydraulic motor of sorts. For the time being I am going to move forward with an electric motor, but keeping in mind the size and shape of a hydraulic motor.

That’s all for now, off to play!