Build a Compost Shredder Chipper

Use these plans from MOTHER EARTH NEWS to make your own compost shredder chipper from a lawn mower. Your garden will thank you.

  • Compost Shredder Chipper Mulch Detail
    Construction diagram. 
  • Compost Shredder Chipper2
    A mobile compost shredder chipper. 
  • Compost Shredder Chipper1
    Start with a self-propelled rotary mover. 

  • Compost Shredder Chipper Mulch Detail
  • Compost Shredder Chipper2
  • Compost Shredder Chipper1

Compost is one of the gardener's most versatile allies. This nutrient-rich humus not only is organic and free for the making but can serve equally well as a fertilizer, tilth builder, or biodegradable mulch for soil-and-weed control.

The hitch is, of course, that the decomposition process responsible for turning trash into treasure can take months. However, that long wait can be reduced to a matter of days if the organic feedstock is properly prepared. And the key to that preparatory procedure is shredding everything that goes into a compost heap. You see, by breaking up the material with a compost shredder chipper and increasing its exposed surface area, you can improve bacterial action . . . and ultimately contribute to the speed and quality of decomposition.

Now serious gardeners have been known to go out and spend in excess of $1,000 for shredder/chippers to handle their composting chores . . . but you can achieve almost the same results at an out-of-pocket expense of $40 or $50, just by making minor modifications on a secondhand lawn mower!

What you'll need is a working self-propelled rotary mower (the kind with the small power takeoff (PTO) shaft at the side of the engine) . . . some sheet metal (the "skin" from an old washer or dryer would work fine) . . . the chainwheel, chain, and guard from a junk bicycle . . . a small sprocket to fit the engine's PTO shaft . . . a 15" piece of 1/2" rod . . . two 1/4" pipe floor flanges . . . a couple of 1/2" X 25" lengths of electrical metallic tubing . . . and some assorted fastening hardware. (If you just can't locate a good self-driven mower, a conventional rotary model will do, though you'll have to carefully hand-feed material into it when using the device.)

Start your project by looking over the mower and making certain there's enough room on its deck to allow you to add a feed chute at the front. If there appears to be a problem, try turning the engine 180° on its platform and remounting it. Once the correct position is established, cut a 4 1/2" X 8 1/2" opening in the top of the deck, centering it directly in front of the power plant. Then, using the sheet metal, form up a 16"-tall, wide-mouthed (11 1/2" X 13"), tapered hopper, with a 3" shield at the top and some mounting lips at the bottom . . . using our illustration as a guide.

After assembling the chute, bolt it squarely over the deck opening and support it with the two conduit braces (just flatten and bend their ends, and bolt the supports between the back of the hopper and the rear of the mower platform). Next, you can secure the small sprocket in place on the engine's PTO shaft, afterward stringing the chain over both cogged wheels. By pulling the links taut, you can approximate a good location for the feed-paddle shaft, which should sit midway between the front and rear walls of the hopper but high enough to permit the large sprocket complete clearance.

Rod Bonner
5/18/2009 9:03:03 PM

A basic diagram in the gallery for this article on how to make the feed paddles in the chute would be helpful. I have no idea how to create a safe yet effective feed system.

Jim Lucas
7/2/2008 1:58:53 PM

On the "Build a Commonsense Compost Shredder" printable exploded drawings or pictures would help many of us more challenged people.

Subscribe Today - Pay Now & Save 64% Off the Cover Price

50 Years of Money-Saving Tips!

Mother Earth NewsAt MOTHER EARTH NEWS for 50 years and counting, we are dedicated to conserving our planet's natural resources while helping you conserve your financial resources. You'll find tips for slashing heating bills, growing fresh, natural produce at home, and more. That's why we want you to save money and trees by subscribing through our earth-friendly automatic renewal savings plan. By paying with a credit card, you save an additional $5 and get 6 issues of MOTHER EARTH NEWS for only $12.95 (USA only).

You may also use the Bill Me option and pay $17.95 for 6 issues.

Canadian Subscribers - Click Here
International Subscribers - Click Here
Canadian subscriptions: 1 year (includes postage & GST).

Facebook Pinterest Instagram YouTube Twitter flipboard

Free Product Information Classifieds Newsletters