I have used my lawn mower to chop up semi-finished compost when the pieces were large. Usually I use the mower or something else to reduce leaves and other ingredients before mixing them together into a starting compost pile. Then the finished material is small enough and does not require further shredding.

Shredding the larger semi-composted pieces gives a light, airy material. I try to avoid larger wood pieces that might ding the mower blade.

If you Search for 'chipper' or 'shredder' on this forum, and the Tool forum you will find hundreds of threads on this subject.

Robert, you're actually able to use the lawn mower over partially composted compost? If so, can you tell me how you go about doing that? Do the pieces fly about when you place the lawn mower over them?

Also, what do you use beneath the lawn mower,on the ground? I hope my question is clear...

Hard to say since you don't have a lawnmower.
For leaves, I was given a leaf sucker/chopper which is great, but I think they are fairly expensive.
You can still run your food scraps through a $5 food processor or blender from a yard sale. You could look for a cheap/free mower or leaf grinder on craigslist, yard sales, flea mart or freecycle.
Good luck and good gardening! Nancy

For many years I have been using an ordinary gas rotary lawnmower to shred maple leaves, before they are used as mulch. Some of the shredded leaves go on the compost pile, where they break down much sooner if they are shredded first. To shred leaves, they are first raked into a windrow, about two feet wide and a foot high. The lawnmower is pulled through backwards, because this reduces scattering. It takes several passes, but the process is very fast. At least the shredding part. Raking up the shredded leaves, sweeping the sidewalk, and collecting all the dust takes considerable time and effort. If the leaves are shredded on the lawn, the leaf dust simply settles into the grass, and feeds the lawn. This is likely the cheapest way to shred leaves, and I think it would work on compost, provided the compost is not too damp. Lawnmowers are inexpensive to own and operate, and they are reliable. The process works OK, but the labor involved in clean-up is considerable. I typically load up a blue pvc tarp with the shredded leaf remnants, and pull this around the yard to where the mulch is needed.

I have a typical gas-powered 300cc chipper/shredder that sits maybe three feet tall, and has two wheels for pushing around. It is way more reliable than a lawnmower, although the claim that it can chip large sticks is suspect. It probably could do something the diameter of a broomstick, but it would take a while, and be very inefficient.

It works great for garden waste like cornstalks, old tomato plants, and weeds. You can sit there and shovel a steady stream of clumpy horse manure in and it will turn it into a nice finely shredded mulch that nobody would know was ever horse manure. I've never used it for food waste, I'd worry it might get gummed up with that sort of thing.

I got it used for 1/10 original price, I imagine they are easy to find used in most places.

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Pictured: Eco Shredder 1600. $100 off of Craigslist. Electric. Another $10 for the improvised adapter (the silver part). I limit it to leaves (large avocado leaves) and twigs.

I've found that my kitchen waste disappears just fine and I no longer entertain any ideas about chopping or grinding that stuff up. Same for the lemons and oranges that drop to the ground and are no good. Avocado skins just take forever though.

I have gone over leaves with the mulching mower on the driveway where I have walls on either side. Then I'll let the mower bag them. Dirty job though. Dirt and dust everywhere. For the bin, I prefer leaves spread out over the lawn while I mow and it chops the leaves some and mixes them with the grass clippings.

to sense
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Kendra, you have 2 problems basically, mulching up the leaves, and mulching up the 'food' portions.

For the food portions there is a method that is quite easy but not perfect. Get a 5 gall bucket (with lid) and you can cut your food parts up into decent chunks (about 4"x4" is ok) then put them in the bucket. That will get ugly smelly pretty easy. When its fullish you just dump it onto your bin of leaves/ paper and stir it all up...

For the leaves you can use one of the blower/shredders (about 75 bucks) which DO work well and I have found as a good investment. I box the leaves in fall and they get stored till I need them. All I do is throw them in a BIG cardboard box for about 48 hours and dry them out as much as possible (drier the better). Then I just suck them up in the mulcher and throw into the compost bin for the new batch. The rest go back into boxes to be used as needed.

Alternatively you can use a weed wacker. Build a cheap 'holding pen' and throw all the leaves in (again drier the better) and just have at it with the weed wacker.. then you have chewed up leaves.

So I know I this is an old thread, but here is my issue. I am looking for a similar solution. My food scraps go into the compost pile as well as yard waste. When I trim trees/shrubs, I put that through my chipper, however there still end up with some larger pieces in the compost pile. More "Weedy" vines and stuff. Sometimes, it's not worth the effort to pull the chipper out for some of it. Anyway, I turn my compost regularly, but I'd just like to have a "Finer" mix before spreading it on the garden. I have, in the past, put it through my Chipper/shredder which I got from Harbor but the screen on the bottom gets "Clogged" as the compost is rarely dry. it's a challenge to always clean it (about 10 nuts to take the cover off to clear out the area above the screen). I can take the screen out but then it's almost like the compost goes in the top and just shot out the bottom at high speed. (The screen helps keep it in to get broken down.

I have a Blower/Vac for leaves (and use it) I mow my lawn (with leaves) to mulch it up. (I don't have a huge amount of leaves to deal with). I just need something that can handle the quasi-moist mulch to break it down smaller.

Find a burlap sack and tie it around the bottom of the shredder to catch the output. I've done this with my gas powered chipper shredder so the stuff doesn't fly everywhere. Works great. If there is nowhere to tie it on, you can make an arc of chicken wire or hardware cloth like a cage and aim the discharge at that.

To avoid having big pieces to begin with, invest in a $10 machete from Harbor Freight or a mil surplus store. Get an old stump or chunk of wood to use for a chopping block, or just make a pile of long stuff and chop the pile right where it lies when you're ready to put it in the compost. The machete requires no setup or fueling, so it's easy to grab for small jobs.

If pieces are that big it may not be done composting. But you can easily make a sifter to fit over a wheel barrow with some hardware cloth and some 2x3's or 2x4's. Recycle what doesn't go thru.

I use a sifter on the finished compost. Whatever makes it through the mesh is "done" and the rest gets tossed into the next active bin.

http://lazygardens.blogspot.com/2015/05/diy-trommel-sifter-for-compost.html 

Ditto.

I guess I just need to make a sifter or trommel. I know if the pieces are larger that it's not done composting, but it can also "Compost" in place in the garden (or wherever) as well. Particularly the "Woody" stuff to provide good nitrogen. I just didn't want the bigger pieces and wanted to grind them down (Plus smaller pieces compost quicker too).

Additionally. I have a lot of egg shells. They are good for the compost but they don't seem to break down as quick as I would like so a grinder would make quick work of it.

I guess a good compromise is to sift the good material out, then throw whats left into the shredder (as without the extra dirt/moisture it won't clog my shredder as much). I was just hoping for a simple (cheaper) solution to be able to "Shovel" the compost in to and to make it "Finer" as far as size of material.

Thanks to everyone for the great ideas though.

Just a little tip. I'm sure everyone wants to find a cheap and easy way to accomplish the task of grinding up their food waste. After reading the comments on this post I searched craigslist and found several chippers for under $100, a few for $75 and even one for $25, which was about an hour's drive one way, so counting gas it would cost $50, plus at least two hours time to go check it out. It was pretty small unit, but that's all you need if you just want to grind up food scraps. There were a few for $150/$175 in the city I live in and the city next to me. You know how craigslist is. If you don't find what you want today, there's a good chance it will be there next week or next month.

I'm curious what food waste one is having a hard time composting. I bury coffee grounds & filters, greens of all kinds, banana peels, beet and potato remnants, and even knobs of carrots, and I never see any sign of them again. I cut big things like celery knobs in a few pieces before dumping them. Those all sure don't need chipping. I routinely bury vegetable plants of all kinds - long winding stems, and after shoving a shovel blade down through the mass a few times, they eventually disappear. Yeah, egg shells don't dissolve by themselves in compost, but whenever I see a piece that is bigger than I'd like to to be, I just shove a shovel blade on it.

At any hardware they sell an ice chopper scraper. It has a long wooden handle with a sharp 7 inch flat wide blade mounted on one end. It is rugged. At a shipyard where I use to work we used them to scrape barnacles off the bottom of boats. Place you kitchen compost in a five gallon bucket and chop away. Keep a fine razor sharp edge on it with a grinder or file. I use this for my compost and you can chop as fine as you want.

The above item can be purchased through Amazon. They have many sizes and prices.

I just want to echo lazy_gardens's point that rather than chop compost - just screen it when you empty it out. The fine material that passes through the screen is "done" and the pieces that are too big go back in the composter. The will eventually break down.

The chopper is used to break down what material I want to compost. It does not take long to do. You can go as fine as you want. For kitchen material I even have use a large food processor. Good to grind egg shells. Once chopped up It is put in a Bokashi Bucket, in a large container or pile where I force air into it by a blower and a system of pipes.

Once the compost is done I place it in a four wheel cart that has a bottom of expanded metal. I have a 12 volt DC vibrator attached to the cart that is used to shake the compost on the top of the expanded metal. Various sizes of the expanded metal can be used. Along with the shaking take a flat rake and push the compost back and forth. (GOOD JOB FOR YOUR SONS OR GRANDSONS)

For yard waste I used an electric chipper shredder and grind the material as fine as possible. Also use the forced air system in the pile. Once done it is easy to sift.

Always use the SECRET INGREDIENTS TO ENHANCE the Garden Gold.

I just took delivery this morning of the super duper chipper machine mentioned by Rayzone, immediately thought of those screens. Sorry to read about the maintenance issues, I'm really bad about that stuff and was hoping there would be less to do maintenance wise.