Quick Made Hand Cranked Compost Shredder





Introduction: Quick Made Hand Cranked Compost Shredder

If you make you own compost, you can see grass mowings and soft young weeds, rot quickly. But small branches and woody prunings decay very slowly.
They need to be shreded to be correctly composted.

If the woody prunings are a small fraction of your compost maybe it is not necesary to buy a expensive compost shreder. You can build a small hand cranked compost shredder.

Step 1: Big Bore Bit Drill

This is the core of the shreder.
A worn big bore bit drill . You need to weld a rod in the tip of the bit drill. this rod must be aligned with the bit drill's axle.The frame is made from wood. take all the measures and drill two holes in the frame, then put two bearings on it and put the axles into them. Fix the frame with nails or whatever you want.

Step 2:

I added this metal plate, as counter blade. The nails are hammered into the wooden frame and rest in the metal blade.After that I welded them together as a reinforcement.

Step 3: Axis

Slide the axis of the drill through the ball bearings.
In the tip of the drill I welded another axis and I did the same.

Step 4: Add a Hand-crank

The hand crank welded into the axis

Step 5: Test

Once the hand crack is finished it is time to test the device.
I took a small branch ( 2 cm diameter), and push it between the drill and the counter blade.
I spun the drill slowly maybe 30 rpm

Step 6: Shredding

You can see that the branches are slowly shreded into fine strips.



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    21 Discussions

    I use a garden pruning shears and a plastic bucket and cut woody stuff into 4 inch lengths straight into the bucket and then compost it. Even blackberry briars go in without handling! and when it is all cut up, it is surprising how many bushes or briars fit into the 5 gallon bucket! I started doing it this way this year. I have to say that i think the plants prefer the compost like that. When it goes out of the composter, the wood is still not completely broken down. But the plants have been growing just great. I always thought compost needs to break down to fine stuff. Apparenty not.

    4 replies

    Thanks for the low-tech option! The chipper design is great, but the bucket and shears idea is so doable, especially since I don't have a giant drill bit laying around.

    The idea of the bigger woody pieces using more nitrogen to break down and therefore being bad for plants seems suspect to me, since in nature, topsoil is built by leaves and sticks that just break down where they land, no chipping necessary. They naturally break down slower, of course, but there seems to be more to the process than chunks of cellulose just sucking nitrogen from the soil. They may make up for it by retaining moisture, and if the plants like it, who are we to argue?

    I just tried "hugelkultur" by burying about a truck load of small branches and rose prunings under the ground in a trench. I simply used the shears to break the branches into about 6 inch (15 cm) pieces and as I cut, the pile subsided and after about 20 minutes, it fit in the hole. Its about 15 minutes drive to the municipal composting center, so I saved about 1 and a half hours (loading, unloading and driving time) with the shears in the trench. As far as I know, it will break down gradually and release its phosphates and potash slowly to the plant roots.

    the wood that is not broken down acts as more of a mulch, which is also beneficial to growing plants if it is kept on top of the soil (helps retain moisture and control weeds). This is a good long term soil builder as it will continue to compost over time. good way of dealing with woody compost.

    When I get out the compost from the composter I try ti remove the biggest pieces of wood which has not being boken down. The wood which is still not completely broken down uses a lot nitrogen for its own decomposition, and thats not to good for the plants. In general the more you shred the prunings into the compost bin, the quicker it will decompose.

    Many years ago a company that made a gas powered "chipper/shredder" - that DID NOT use spinning blades. They had 3-6 shafts each having multiple hammers (flails) to smash the small pieces of wood by spinning on their shafts. Very old mowers used this concept - and even today most state highway departments use heavy-duty flail mowers along highways. The number of "flails" correlates to the size of the debris. Some universities use this apparatus to separate "seeds" as well.

    What about gearing to increase force or perhaps attaching something like this to a garden tap and using water power? Perhaps a flat blade 'waterwheel' attached directly to the bit?

    1 reply

    Increasing cutting force would require a sturdier, this wooden frame can't take much more and a reduction gear box at least.
    I use this shreder to chop thin elderberry branches, and that set is enough to do the job and keep things simple.
    But if you're looking after improving the maximium potential of a hand crancked shredded, then there's plenty of room for improvement, I think that's the work for another instructable.

    Man ... where I worked as a machinist that drill had about 10 more inches of life left on it! :-) What size drill? Looks like about a 2-2.5" bit. Did you sharpen the flutes?

    1 reply

    Sorry for my late reply. That drill was useless to me so I didn't sharpen it, it's bore is 50mm. The only use for such a big drill for me was this.
    Thanks for your comment.

    Where can I find a bit such as that on the cheap?

    Just what Ive been looking for! You would think that a muscle powered chipper/shredder would be easy to find in this day and age of green marketing, but no.
    There were some on the market years ago, but no longer. I have tried meat grinders to no avail.Your solution is so elegant.Thank you!

    1 reply

    Thanks,maybe it's an elegant solution, but I warn you, using this shredder can be quite exhausting.

    An idea - connect to an old bicycle that has been geared down to a very low speed, stick the spouse or kids on the bike and you have 2 hands free to feed in the material constantly.  Geared down as suggested, there would be tons of torques and the family gets plenty of exercise.

    1 reply

    Hahaha, thank you for your idea, I'll think about it, but I don't know what  my family will say about it.

    Hmmmm. Two of those bit bits opposing each other might make for a very effective apple masher for cider making...

    1 reply

    uuuhmmm, maybe with some small modifications ... The flutes in this drill are really big and many pieces of apple would pass through without being squeezed ...