r/composting • u/DckThik • 1d ago

Builds Trommel build

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Hello all, first post here. I am building a composting trommel and could use some advice. The drawing is a rough sketch of where it’s going. I’m considering the motor for this now. I’m uncertain of the rotation speed and amount of torque it will need to run a belt and pulley.

I haven’t settled on a finished length. I have some 700cc rims on the way (listed as RIM WEI 700C 622x16.7 AS23X 36 SL/NMSW SV). I’m waiting until those get here to measure the inside diameter for 1/2 hardware cloth and the width for the fender washers to hold rivets and mesh. Haven’t selected rollers yet either. Base will probably be board, screws, and brackets with wheels on one end to move it around.

I have a circa 2015 dewalt 20vXR weedeater motor and controller/battery assembly I was gonna use but the lowest rpm is around 4000 lol. The control assembly is useful and the motor would be too if I knew enough to put a gear reducer on it. I’m fairly handy so if there’s a good technical solution I love a challenge and tinkering.

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u/wriky 1d ago

Looks unnecessarily long, my commercial one is a bit shorter than 1m (3’). It comes with a 400w motor which is enough. Also you would want the motor above it, so it doesn’t get all the dirt in to the bearings. Would also add a couple of aluminum angles along the length of the drum to lift and dropp the compost, helps breaking upp the lumps.

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u/DckThik 14h ago edited 14h ago

Good to know it can be made shorter. My idea was to let the tailings fall out the far end.

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u/fisherman206 12h ago

You are on the right track. Think about where your bigs are going to fall out on the lower end of your rig. I position mine so the bigs fall right back into my active bin once they exit the sifter. Also wise to think about ease of getting unsifted compost into the rig. 700 bike rims are good because you don't have to be very precise when loading with a shovel. The photo above looks like the opening to load material might be a bit small of an opening for my taste.

Generally speaking, the more efficient your process, the more fun you will have and the more often you will fire up the rig.

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u/wriky 5h ago

Yeah it’s on the small side, have to use a pretty slim shovel.