Shredder for (sometimes) wet garden waste, not to chip wood

I tremble at the thought of suggesting such a blatantly non-HUSP-compliant apparatus on permies.com, but so be it.

We have a community garden with about 70 plots of 25m2/250 sq ft. We have mass "barn-raising" days every once in a while in order not to raise barns but to make and turn compost piles, clean and beautify, and remove (heaven forbid) "weeds" from the common areas.

We are looking for a machine to make it quicker and easier to build effective hot compost piles. Our typical pile consists of a bijillion tomato plants all rife with late blight, some with big fat juicy blighted tomatoes still on them, tough discarded pepper plants, bulletproof brassica stems and roots, plus all kinds of weeds, grass and veggie leaves, sometimes diseased with powdery mildew etc. To kill off all the bad guys we need our compost pile to get hot, and we are getting better at building them correctly but honestly we need all the help we can get.

This stuff sits around in a pile in our fairly-rainy outdoors until a community compost-raising day comes around, when it may or may not be pouring rain. So the outside of our piles is often wet and the inside of course is usually dryish -- things can accumulate for months.

Anyway, to reduce the RSI of our team of machete-wielders and speed up the compost-pile-building process, we are looking for a shredder to handle the kind of stuff we will be feeding through it. In addition to the above ingredients, we will usually have a bit of manure of some sort (no shredding needed) and some not-very-shredded hay from a local farm or perhaps dry or wet leaves from the park across the way depending on the time of year. So we want our machine to be able to handle loads of wet leaves in addition to the above if push comes to shove. Even the cheapest shredders would seem to handle dry hay just fine.

Our compost-pile-making area is a long way from the nearest electric outlet -- maybe 200m/yards? In addition, all the reviews of every electric shredder or chipper/shredder I've ever seen warn that this device does NOT handle wet material well.

In fact, the only devices I've ever heard of with decent reviews for shredding wet garden waste have been gasoline-powered (ugh! I feel my principles slithering down a slimy drain) devices with hammermills and free-swinging hammers. (Why you cannot power a hammermill with electricity seemingly is beyond me.) We already have a gasoline-powered weed whacker so I suppose this is just another ways down the slippery slope we'd be traveling.

Anyway, we're now considering devices from MST and Garland that are within our budget but whose technical details we're not so confident about, and a device from Mighty Mac (the SC800) that is 2-3x what we have budgeted but we're pretty confident it can do the job.

I would love to know what some other wise and experienced permies think and have done on the subject.

PS - And if you use a device that shreds wet garden waste well, please let us know the make and model number! Thanks!

Here's my grain of salt, two cents worth:

I don't have the answer that you are looking for, because you seem to be at odds with your gas consumption question... and yet see to be also settling for this as your solution.   So I'm not going to suggest any gas models of which I don't have any to suggest to you anyway at this time.

Also:  I may be wrong but the problem with electrical is likely that the force of surges that are needed to run rough heavy material through blades or hammers is the type of load that would require more amperage than a regular electrical socket would provide, so most models are gas powered, or you would have to plug them in in the place of a welder or a clothes dryer.  The result of running any hard material in an electric model is that it would not handle it, it would jam, it would jolt the machine from high RPM's to zero, it would blow your breaker, and might break the machine.  BUT I'm no electrician and have no experience with electrical shredders.  

That all said, here's my brainstormed PERMIES SOLUTION(?) :  If you have anybody around in the DIY bike community who have a proper shop and some time, and once built you utilize the volume of 'barn raising' bodies to pedal it all at once to generate (via slowly gearing up) the massive RPMs of a heavy fly wheel, I'm pretty sure that you could get a bike powered hammer mill or blade system that would be able to handle anything you chucked in the chute (be sure, of course, to design this so that nobody can get involved in the blades/hammers).  But I'm just a dreamer, envisioning something not an engineer with a working prototype.          

Dave, what you are looking for is an agriculture waste shredder.  I am looking for the same thing,l and did the research not too long ago.  Sorry to say that you may have to import one.  I'll give you a couple of links I found.  I watched a video of one processing coconut fronds and banana plants, you can't get much tougher or wetter than those!  I have dealt with both in south Florida.  There are electric and pto models available.  Some years ago I imported a 700 lb sugarcane press from India.  I saved a ton of $$ doing all the paperwork myself and learned a lot.  I know the carbon footprint represented by the shipping is huge, not sure if it's worse than sepp or Geoff flying around the world teaching pdc's.  Believe me, I have looked far and wide in the US for these things and what I found is either huge industrial models or hugely expensive tiny ones, no "market garden" sized ones.  I have had Indian (dot not feather, for the non-pc challenged ones) friends translate for me when talking to Indian manufacturers.  Most are willing to crate and put their machines on a boat for you.  Anyway, here are some links.

http://m.kovaiclassicindustries.net/agricultural-shredder.html


 https://m.youtube.com/watch?v=IREnL6K4K5o

http://www.jaiindiraagro.com

Good luck
Kevin

I've been searching for a "meat-powered" chaff-cutter for a while, and found some still produced in India.
I got some quotes, but the shipping cost is huge.

In my experience, they key to a hot compost pile is plenty of manure wastes.

Our hottest compost piles have always come from when we were using composting toilets and adding them to our typical garden waste mixtures. We have never been keen on turning piles, so our heaps get super hot for a while, then sit for a year to finish off. Pretty much the only things that come through uncomposted after 12 months are really woody branches - usually horrible thorny rose prunings which should never have gone on the heap in the first place.

If your community allotments get a lot of traffic, consider setting up a sawdust toilet for general use.

Hmmm... interesting replies!

AND... if anyone reading this actually uses a shredder that handles garden waste, more green tough and fibrous than dry, please chime in with a make and model! Mega bonus points if it costs less than $1000 and is smallish and portable!

The actual model we are considering at the moment is a (link in Spanish but you can probably understand the tech specs down below) Garland 790G which looks a lot like a Mighty Mac model I'm pretty confident would work for us (the SC800) and from what little info I can find in the tech specs, it seems like it may have a hammermill with free-swinging hammers. That's what I've been told (by a Mighty Mac salesman) I need, though I'm pretty sketchy on the free-swinging hammer bit, not being an expert in hammermills. Yet.

Roberto, I love your idea of a mass bike-powered flywheel powering a DIY hammermill! That is not a short-term solution for us but it is a great long-term goal -- maybe we could pull it off around here! We've got lots of bike fanatics, mechanical engineers and welding and boilermaking shops! Thanks for a real permie permie solution! By the way, being in Europe we are on 230V, the equivalent in NA of plugging into the electric dryer outlet, but still, I'm not seeing electric models advertised even here that would work.

Kevin, thanks for the suggestion of an agricultural waste shredder, that gives me another search term to use! These Indian models could no doubt do the job, but are still too big for us. Our entire community garden with 70+ plots fits on well under 1/2 an acre, about 2000m2 if you throw in a lot of the common areas. We have very, very limited storage space, so it needs to be smallish. Also our budget is really around $700-800. We might pay more if there's no way to do the job done otherwise, but that's our limit now... should've made that clear from the outset!

André -- would a chaff cutter necessarily handle wet stuff and tough/stringy stuff like old pepper plants and cabbage stems, etc? Anyway, thanks for the warning on the shipping cost.

Michael... right, very timely warning! We're building our next hot compost pile this coming Saturday the 22nd, and you've reminded me we need to order up a trailerload of cow manure and maybe a dozen bails of hay from the farmer up the road! With maybe 200 people pitching things into our compostables pile, there is no practical way we can keep all the unwanted things out (like rose prunings or what have you), we just need to deal quickly and effectively with whatever's in the pile. (Of course we remove anything stupid like plastic vine trellising, but everything else goes straight in as it's our only waste outlet.) Town hall here supplied the toilets already and they're the plain old flush kind, and I think there might be a bit of political flack at the thought of humanure in our veggie gardens, so I can't see a sawdust toilet on the horizon here any time soon. Ideally, we'd like to get our composting system efficient enough to be on a 4- or 5-month cycle, so October's pile is ready by the beginning of April and November's by the beginning of May. We don't have too much space to keep it around. That's another reason we want to shred, as well as turning a couple of times.

QUESTION OF THE DAY: Any good experiences with a garden waste shredder out there? Which one? (Mostly for annual plants, not leaves, grass, branches or woody stuff)

Dave, I have a troybuild super tomahawk chipper shredder.  It is a hammermill shredder.  It works great for dry stuff, really sucks for wet material.  I have used it for tree/bush trimmings, fallen leaves and to process commercial tree mulch.  Wet stuff tends to wrap around the shaft and sticks in the screen and clogs.  That is why I've been looking for a device to handle wet material.

Thanks Kevin!

Wow, this is both great and terrible all at the same time!!! Thanks for the heads-up!

So it is possible for a hammermill shredder also to suck at handling wet stuff. This makes me rethink the purchase of the Garland machine I linked to above as that's really all I know about it. Darn. I mean, good.

Anyway, maybe it is the mysterious "free-swinging hammers" that makes the difference, like the Mighty Mac salesman told me? Do you know if your Troybuild has free-swinging hammers? Maybe this is just a bunch of sales sweet-talk. Any hammermill experts out there?

Or maybe it's a screen size issue? Does your shredder have different screens you can use? If so, which one delivered sucky performance on the wet material?

Or maybe the truth is that EVERYTHING sucks at shredding wet material but just no one wants to come out and speak the bitter truth...

Well, anyway, at least we're a team of two now, looking for something that can shred wet stuff... Hope we find it...

Dave, yes my troybuilt has free swinging blades!  I have removed them many times to sharpen them.  They are carbide, sharpening takes a special grinding wheel, but is easy.  They have 4 cutting edges and swing freely on horizontal shafts with spacers to keep them in position.  There are maybe 20 or so blades.  I have 3 screens, and generally use the medium screen.  Even with the large holes in the large screen, wet material sort of ends up building up over the web between holes,  real pain in the butt to clear.  Even when I process fresh leaves from trimming, I find it helpful to run dry material pretty regularly to keep the screen clear.  It's a great machine, but has limitations,  if you don't clear the output shoot clear, you will have problems, and no matter what the salesmen say, wet stuff doesn't shred well.  I have seen the advertisements on other chipper shredders saying amazing things, but after using mine for 20 plus years, I dont believe any of it.  I grew bananas and coconuts in Florida and made the mistake of trying them in my shredder, once!  That's why I was excited to see the Indian videos of machines taking whole banana trees and coconut frond and spitting the shredding over 10'.  My shredder dumps the shreddings maybe 2' max away from the machine, so you have to continually pitchfork the material away from the chute, so you end up handling the material several times.  Hope this helps, sorry I can't say a hammermill shredder will do more, I would love to be able to dump all of my expired garden plants Into the shredder, but would have to wait till they dried out sufficiently.

I've used a Mighty Mac hammermill shredder for a couple of decades. It works excellent on dry material, and moderately well on moist material. With very moist or wet material, it clogs even with the screen off. For your tomato plants, I would say there's enough coarse vine to keep the shredding chamber clear as long as you use a large screen or no screen. 1" screen would probably clog if there is a lot of tomatoes.

I've run compost-in-progress through it with no screen on. Never clogged even though some pitchforkfuls were rather wet clods. I had a local welder make a bar screen with the bars set 1 1/2" apart. This worked far better than the screens with circular holes.

Now for something that will horrify most gardeners......I use a 6.5 horsepower gas lawnmower with a grass catching bag to do most of my initial shredding of biomaterial. It can handle just about all garden waste except to bottoms of corn stalks. Even the thickest tomato stalks and broccoli stalks get chopped enough for composting. I'm aware that there are some pretty powerful electric lawn mowers out there, even some strong battery powered ones. But I don't know what's available in Europe.

So OK, now I'll fess up. Our stuff isn't likely to be *all* that wet. If it's pouring rain on compost-raising day we'll put it off till the next week. And it's not *really, that* rainy around here.

So here's my evil plan -- do you think it might work?

Let's say this Garland machine I've got my eye on is not as good as Su's Mighty Mac, it's about like Kevin's Troybuilt. Hope springs eternal, I hope we don't buy a €700 lemon.

About half our compost fixins are *dried out* plants, including brassica stocks, pepper plants, whole tomato plants with tomatoes, "weeds" and loads of other stuff. Another 40% is the same but fresh and green. The last 10% is the outer layer, which is the same but pretty wet from a few days of rain that just let up yesterday.

Enter, stage left, for compost-raising day, about half the volume of our compost fixins in bales of dry hay.

And let's say we leave the screen off this non-lemony Troybuilt-like shredder for the first pass.

We alternate the wet outside stuff with dry hay and then throw in some dry and green middle-fixins. And we get through the pile with almost no clogs.

Then, since we want this pile to compost fast, we put a 1" screen on and feed it all through again. The wet stuff won't be as wet since it's mixed with a good amount of dry stuff now. So it won't stick, will go through and get minced up just fine and we will all live happily ever after.

Ooops I forgot, then we layer the product of round 2 with fresh cow manure (like 10% of the volume of the original pile), water well, throw some hay on top to keep the rain off, and we're cooking.

Do you people who've actually used these things think that this is outrageously idealistic? Or maybe might work out like this?

PS - What's the safe way to unclog one of these contraptions? Don't want anyone losing a hand.

Have you found an affordable solution yet?  I found some waste wood grinder and bark hog videos on youtube, looks like they would work.  I can't find one scaled down for home use or affordable.  

http://hache-paille.top/
This kind of manual shredder can be found antique or imported from India. The antique kind sometimes have a table attached. Takes two people to operate.

This thread might be dormant but I’ve had great luck with a cheap, electric chipper shredder from Harbor Freight. It doesn’t take anything larger than 1.5 inches, but it deals w large collections of reeds pulled fresh from our rain garden, which are both very fibrous and high moisture.

It isn’t the highest /capacity/ machine, but so far it works great

Haven’t tried any tomato stems yet tho!

Sounds to me as if this is too small scale to meet your goals, but I picture it coming together for under $100, not including the cord. If your material is wet and tough and fibrous, but not woody, this would likely work, though much more slowly than the solutions you've been considering.

Get a used IBC tote, cut off the top. Get a used sink and garbage disposal. (I think I could get those for around $30 at habitat for humanity restore. Do you have a local equivolent?) Mount them on top of or above the IBC tote. Install a screen made from hardware cloth for the solids to land on. If it's large and tilted, I think it would clog less frequently. Put a pump in the bottom of the tote, with enough water to keep it from pumping dry. Use it to pump strained water into the sink, so the disposal doesn't run dry. I think a $19 harbor freight pump would work for quite a while, but a more expensive pump that doesn't mind pumping solids would probably last longer.

After you're done, (If you ever get done, using this slower solution.) drain the water and wet compost piles or water gardens with it.

I have been trying to figure out the wet/green compost solution all year.  I have been running the battery powered lawn mower over it and it works OK - but the idea of a garbage disposal and pumped/strained water is genius!  I am on the hunt for supplies and hope to have it in operation soon.  I feel pretty stupid for not coming up with this.  Slow? perhaps - but efficient.

David the good (David Good here on permies) did something similar after I posted that. Here's the video. You might consider going to the page on youtube and reading the notes. He describes the build and links to some of the parts he used.

The OP was about reducing vines and big debris, in order to compost it. The material is green/wet (neither sopping WET, nor dry). Labor is manual.

I've found that long, tough materials such as stems and vines are a real hassle when building/turning a compost pile by hand. These act a bit like rebar in concrete, tying the whole pile together, making it difficult to pickup just a fork-full for turning.
After a few of these difficult turnings, things improve, as the stems break down into shorter, softer segments. Chopping at the outset is tiring work. Folding/crumpling the stems is easier to do at the time of pulling/collecting, and speeds up the composting breakdown.
Some use a rotary lawn mower as a shredder/chopper, with some success, or a dedicated shredder; but vines and stems can get tangled in machinery, resulting in difficult/unsafe disentanglement.

Maybe just trampling under foot, or driving over with a car/truck/tractor would get the job started enough for the microbes to finish it more quickly. Focus on building a good pile with balanced greens/browns/moisture and it should go better.  No need to get/use another machine, just a vehicle you already have.

If the volume is large enough, then a tractor with a loader can handle the brute labor, and the vines are less of an issue.

I just finished processing a bunch of vines and branches, by hand.
I used crappy secutars, grabbing handful, and cutting the bundle where it stuck out on either side of my fist .
What remained in my grip went on the finished pile.
I continued till everything I grabbed was about 8" or less in length.
It took quite a while, but it was satisfying.
I dumped it on the raised beds over at my yarden, where it will be covered this years autumn leaves.
If I were concerned about regrowth, I would torch it after it was spread onto the beds.

The woody bits  I separated out.
They have been laid on the path that goes behind the greenhouse.
As I tromp across it, it will lay down and decay somewhat.
It may be made into biochar, rocket stove fuel, or wood chips, or it might just become a hugel of sorts.

Hi,

Have you considered using chickens?
Or animal/insect labourers?

The could be substituted for human labour!

Interesting thread. Sounds very familiar. I'm settling for a summer solution of first running vines/fibrous stuff and kitchen waste through my chipper first....taking care to alternate wet/sloppy with dry/fibrous to avoid wet jams....then sorting it through chicken wire into my hammermill shredder (ditto wet/dry). Comes out ready for composting as green.

In northern Minnesota, winter makes this difficult so I try to put a pail out to freeze till I can process/compost in spring when other green is still hard to find.  Worms made an unsuccessful mess for me; others have made it work but getting it small is still an issue. Also looking at kabocha as an option, but can't use it for compost then.

So I got here trying to find a reasonable manual chopper-grinder.....much more difficult than expected. The best design I've found has plastic blades that would just not be up to it. Electrics that might work are unreasonably pricey and most are made for leaves and small sticks. Still looking.

I have repurposed apple grinders for these types of wet materials.
These types of grinders are used in the first step for apples or grapes before they are pressed for juice. It's amazing at chunking things up.

I run a composting set up with a food bank and community garden. I originally had the manual crank grinder and then upgraded to the electric one.

I throw all sorts of wet materials through them.

I can't speak to it's use for vines. Tbh, when the vines come in, I spread them out to dry in the sun for a few weeks. Then I hit them with a mower.

https://a.co/d/1KfgdK8

https://pleasanthillgrain.com/maximizer-fruit-apple-grinder-press

I also came across this write up:

https://www.drpowerblog.com/14-day-composting-with-a-dr-chipper-shredder/