Our sifting ability has taken a leap forward!
Tiegan, who just turned 12, has completed his rotary sifter project. One of the main areas in his homeschooling right now is “applied math”. With this in mind and a budding interest in engineering, he started on a path to find a way to improve our sifting for various farm related projects.
I previously posted about our compost sifter, just using shallow boxes that have various mesh sizes of hardware cloth in the bottom. Sifting rotten logs through these has given us quite a bit of high-quality potting soil. It is a fair bit of back labor, however.
After looking around the web for a few design ideas, Tiegan set out on the mission of scrounging parts for his rotary sifter. He ended up having to purchase the 1/2 inch mesh hardware cloth, some dolly wheels and some cable ties. The heavy iron stand was salvaged from the scrap yard (the owners donated it free once they found out it was for a homeschool project!) and the three old bicycle tire rims were picked up for free from bike shop dumpsters (with permission). Tiegan kept some of the gears and drive setups from the bikes in case he wants to play around in the future by attaching a belt drive to the sifter to make it go even faster.
Here is the builder/designer with his completed system:
The design is pretty straightforward – once he had the diameter of the bike tire frames that would fit in the iron frame that is the base of the sifter, the hardware cloth was cut to size and fastened using cable ties through the holes in the rims where the spokes used to be attached.
With a tire rim on either end to provide the form for the tube, a third in the middle was added for more stability and to allow for the belt drive upgrade later on, if desired. Once the tube of hardware cloth was fully assembled, the dolly wheels were installed on the iron frame to line up with the tire rims.
Getting everything lined up so that the wheels were in the right alignment to allow them to spin freely inside the tire rim guides was probably the most tricky part.
Once everything was fully assembled it was ready for testing:
Here is a video of the boys working as a team:
As you can see from the pic above, the rotary sifter quickly processes a wheelbarrow load rotten log chunks into large chunks of rotten wood that need a bit more aging that fall out the far end of the tube, and a nice pile of fine pieces of wood that are perfect for potting soil and for amending the holes for planting trees/bushes/etc…
The larger pieces will be set aside to age and will be a great start to formal compost piles. Once the soil drys out a bit starting in another month or two, we will be able to use the sifter to remove gravel and other debris from areas that we will use for planting smaller perennials like strawberries and dedicated veggie beds.
Tiegan was thrilled to see his contraption working well and we covered the cost of his materials plus a nice bonu$!