Shredders Turn Dead Branches into Mulch

A chipper shredder turns your yard waste into mulch. When deciding which to buy, consider how far from a power source you plan to work and how heavy the material is you plan to chip.

Most shredders have a similar design: There's a hopper on top for loose material and a side opening for pruning clippings and small branches. Shredders differ primarily in the size of the hopper, the size and type of the cutting devices, and the power of the engine.

How Shredders Work

The hammer mill method is most common for shredding small to average materials. Rows of short free-swinging lengths of metal are fixed to a drive shaft that flails the plant material into small pieces.

The material is held in place near the shredding devices by a metal screen with holes about 3/4 inch in diameter. After the hammer mills break down the material, it passes through these screen holes. Some manufacturers offer a wide choice of screens, with holes ranging from 1/8 inch up to 2 inches so that the user can vary the size of shredded material. Most models also have a roller bar system that's used instead of the screens for handling wet or green material that doesn't pass through the screen holes easily.

Once the material is cut, it is thrown out a chute on the shredder's bottom or side. Some models come with a pan to catch the debris; others provide bags. In both cases, the purpose of the container is to move the shredded vegetation to the compost pile or to the garden for mulch.

Selecting a Shredder

Shredders come in electric and gas-operated versions. In deciding which to buy, consider how far from a power source you must work. Gas models can be taken anywhere, even into the woods to shred a pickup's load of fall leaves; electric shredders must stay within reach of the nearest electric outlet.

Engine sizes range from 3 to 8 horsepower. The larger the engine, the heavier the material it can handle, but the cost increases proportionally.

Better shredders are built of 12- to 16-gauge steel; less expensive ones are made of sheet metal. Steel has the advantage of greater strength and durability. Screens should be readily accessible so that you can change them according to the size of compost desired, or remove them when they get clogged. If you live in a wet climate, be sure to get a model with roller bars in addition to the screens.

Safety

• Always wear protective goggles when working around a shredder.
• Never push material down the hopper with your hand. Use a stick.
• Do not let children feed the shredder or even play nearby when it is operating.
• Unplug the power cord on an electric shredder or remove the wire from the spark plug on gas-operated machines before attempting to clear a jam. Make sure the plug wire cannot fall back against the plug.
• Know how to turn the machine off quickly.

Maintenance

Follow the manufacturer's recommendations for cleaning, sharpening and lubricating. In general, cleaning involves washing out the hopper to remove the residue and keeping the screens unclogged. Check the hammer mills, or steel flails, at least once a year (more often if they are used extensively). If any are broken, replace them.

Gas-operated shredders require routine engine maintenance. Virtually all shredders use a four-cycle engine, so the oil needs to be changed about every 25 operating hours. Use a 30-weight oil or whatever the manufacturer recommends. Consult the owner's manual and follow the engine maintenance and tune-up guidelines.

If the shredding devices don't work but the engine does, the problem probably lies with the clutch or the belt. Check the owner's manual for trouble-shooting advice. If the problem isn't something you can handle comfortably, take the shredder to a competent repair shop or to your dealer.