EG's compost turner, part 1 of 4

When a person needs to make large quantities of homemade compost, it can really be a back-breaking chore unless you have the tools to turn the piles mechanically. Keeping 3 pallet bins of ingredients turned weekly last year with a manure fork almost killed me - especially at 41 years of age. Since I would need twice that amount for the upcoming growing season (6 pallet bins total), I decided to construct an electro-mechanical device to turn the three new bins for me - with minimal input from this aging body of mine. It was time to use the various skills acquired over the last 23 years to make my life easier.


Ya know, building a system for my workplace would be a piece of cake, because industrial equipment is what I've worked on for over half of my life. The possiblities would be limitless, because we have electric motors as large as 2,000 horsepower, and have voltages as high as 13,000 volts. But at home, the various tools, equipment, and utilities just aren't available. So, I had to put my thinking cap on, and design a system that was relatively small - but had alot of torque characteristics to effectively turn the piles in place. Talk about tricky! The confinements of the bins themselves was the biggest obstacle, so I decided to design a vertical machine to lower into each bin. The idea will be that the screw will lift the contents from the bottom to the top of each pile, which will effectively cause the contents to heat up again. Using a stick of some kind, I should be able to push the outer part into the middle, which will allow the screw to grab hold of everything.


Anyway, this is my initial drawing of the system, which at least gave me something to kinda go by. It's not precise/complete, but serves the purpose of at least illustrating the general idea. I had to mark the corners of the page that was scanned so that it would upload correctly, in case you're wondering what the slashes in pen are.

Through an unbelievable gear reduction (160 to 1), a 1/2 horsepower electric motor and gearbox will turn an 8" auger at the slow speed of somewhere around 11-12 rpms/minute. So, it will be turning while being lowered down into each pile by a nylon rope and EG power. Once in the lowered position, i'll attach the end of the rope to something to hold it in place for me. This is where the 4 pulleys come in - as they will allow me to raise/lower the powered auger while only having to exert 1/4 of the force that is normally needed to lift any given weight. The entire auger assembly only weighs between 60-70 lbs., and will only require 15-18 lbs. of downward force on the rope to raise/lower it. This is called "mechanical leverage", and is a real life-saver on my aching back! A small child should be able to operate the thing, but of course I only use this terminology to explain the minimal effort needed - not that an actual child will be out there playing with it. (This is certainly not a toy!) A separation will exist between the smaller pulleys (although not depicted on the drawing), and the rope will be intertwined between all 4. This is what gives me mechanical leverage - which will be explained later. I'll probably incorporate a small winch of some kind to make it even more easy to do, but that will be on down the road......

According to my calculations, about 247 ft.lbs. of torque will be available at the screw section, which should easily drill right through each pile. The idea will be to let the screw lift compost from the bottom to the top, while maneuvering it around the internal area of each bin. I'll just have to try it out to see if it's strong enough to lift the contents, once they become compacted from the decomposition process. (That's when the ingredients get pretty heavy) If not, the motor will be increased to 1 horsepower, which should theoretically double the amount of torque. Due to limitations with electrical supply power in this location, I wanted to try the 1/2 hp first - which should require around 8 amps of current @ 115 volts ac. Increasing the horsepower to 1 will actually double the current draw (16 amps), which is right on the threshold of what most heavy duty extension cords can safely carry.


I searched high and low for something similar to this on the internet, but it seems that I'm the first retard person to put something like this into actual thought - then action. A few bugs/quirks are expected, but they'll be dealt with in a timely manner. My theory is, that an answer exists for every problem we encounter, and it's our job to discover or find it. No biggie. I've put some thought into the possible problems that could be encountered, as well as the remedies for each. (I've already completed the project in my mind, as usual).


The next installment of this series will discuss the support structure requirements, and how to get more force by gear reduction. As noted in the post title, this will be a 4 part series, and I hope you enjoy it!

Take care, and happy gardening composting!

EG