Chipper-Shredders

A chipper-shredder is really two machines in one. The chipping mechanism turns tree limbs and branches into chips for use as mulch; the shredding mechanism converts softer materials, such as plants and leaves, into a form suitable for the compost pile. When you shred debris before composting it, you increase its surface area tenfold, which means the debris will take only weeks to decompose instead of months.

The shredding mechanism also has hardened-steel blades. Unlike those of the chipper, which remain in a fixed position, they swing freely and number from eight to 28, depending on the manufacturer. To shred something, load the materials into the chute or hopper, and let the machine do the work (figure C).

No matter how powerful the machine, it will eventually clog or jam, so when you're shopping for a chipper-shredder, make sure the shredding chamber is easily accessible. Shredders with discharge screens are more likely to clog than those without screens, but Paul James recommends using a model with a screen (figure D). The quality of your shredded material will be better if it is pushed through a screen first.

Wood chips can be used just as you would use packaged wood mulch, but as they decompose, fresh wood chips rob a great deal of nitrogen from the soil. For that reason, you should compost them for up to a year or add a generous dose of blood
meal--basically pure nitrogen--on top of the chips and water well.

1. Read and follow the manufacturer's instructions carefully.
   
2. Keep kids and pets well away from the work area.
   
3. Stay clear of the discharge area when the machine is running.
   
4. Avoid loose-fitting clothes (they can get caught in the machine).
   
5. Always wear gloves, ear protection and safety goggles.
   
6. When filling the shredding chute, use the plunger provided to push material into the shredding chamber. Never use your hands or anything made of metal.
   
7. If the chipper/shredder becomes jammed, turn it off, disconnect the spark plug and wait for all moving parts to come to a complete stop before attempting to unclog the machine.