How To Sharpen Garden Shredder Blades

Over time, shredder blades can dull, and become blunt. You can get them sharpened professionally, but this can cost upwards of £20 per pair, plus they dull easily especially if you mistreat them. So sharpening your own is a skill well worth learning.

Some experts advise shredder blades should be sharpened every 25 hours of usage, or once a year, or whatever comes first. Others say you should sharpen the blades after every 6 to 7 hours of usage.

Why Sharpen Shredder Blades?

Every item that goes through your shredder has to come into contact with the blades, and every time the blades cut something, they get slightly less sharp. Like any blade, once it loses its edge, it has a harder job cutting. This will make the motor work harder, and if ignored long enough, the motor will burn out. It’s good to get into the habit of checking the blades before every use.

Shredder blades are like your carving knife in the kitchen, when it’s sharp it glides through meat, bread or whatever you cut with it easily. Once it starts to lose its edge, you have to exert more pressure to cut through even the thinnest of slices of bread. It’s the same thing with the shredder blades. If they look slightly dull, or have little chips or nicks in the blades, that is a sure indicator the blades need to be sharpened. 

Sharpening the blades will prolong the life of your shredder, and sharpening them often will save you from having to replace the blades too often.

How To Sharpen Shredder Blades

To sharpen your shredder blades and ensure your shredder lasts for longer, just follow our easy step by step guide. The first task is to remove the blades from the shredder, this is a handy skill to master, because at some point those blades will have to be replaced. Here are the tools you will need: a disc sander fitted with a 100-grit sanding disc, a vice, allen keys, spanners, monkey wrench (adjustable spanner), impact driver, socket set, camera and a bowl (for holding nuts, bolts and washers)

  1. Switch Your Shredder Off
    Be sure your shredder cannot start up whilst you are working on it. If it’s a petrol-powered shredder remove the spark plug, if it’s electric-powered be sure to remove the plug from the mains.
  2. Remove The Hopper
    The hopper is attached to the frame of the shredder using nuts and bolts, using your socket set and if necessary the wrench, remove all of the nuts and bolts holding the hopper in place. Put the nuts and bolts into a little bowl to keep them safe and easy to find later on.

    Some shredders have a hinged hopper, making it unnecessary to remove the hopper. Just unclamp or unscrew one side of the hopper and lift it to open and move the hopper out of the way.
  3.  Reveal The Flywheel
    Remove all of the bolts around the housing of the shredder, with the plate removed, you should now see the blades. This might also involve the removal of a  flail screen. This is like a mesh screen that prevents wood chippings from gumming up the works. Some models don’t have a flail screen, if yours doesn’t have one, it’s not a problem – in fact it’s saved you some time.
  4. Detach The Housing
    The housing is a metal case that surrounds the blades and the rotors. Undo the bolts retaining the housing, remove the housing, you now can get to the rotor assembly. Take a photo of the flywheel assembly and the housing, this will make it easier to put everything back in the correct place once the blades are sharpened.
  5. Remove The Bolts Retaining The Blades
    These are often allen key bolts and can sometimes be difficult to remove, as it’s hard to get a grip on allen keys. This is where the wrench might come in handy. Grip the allen key with the wrench, this gives you much more torque and the bolts should now come out easily.
  6. Remove The Blade
    The blade might need sharpening, but it will still be extremely sharp. Wear gloves, and hold the blade by the sides not the edges.
  7. Secure The Blade In A Vice
    Once the blade is secured into position, sharpen the blades using the disc sander.
  8. Get The Angle Right
    Sharpen the blades by passing the sander over the beveled edge using quick short strokes on the blade. Match the angle that’s already on the edge of the blade. If the blade is double edged, spin the blade around and do the same thing to the other side.
  9. Reassemble The Shredder
    Just reverse the above steps and your shredder is sharp, and ready to operate again.

Replacing Shredder Blades

If the blades are beyond repairing through sharpening, then you will need to replace them. Just disassemble the shredder as above but instead of sharpening the blades replace them with new ones. As long as you take care with what you put into the shredder, you should get many years of service from it with no problems.

Frequently Asked Questions

How long do wood shredder blades last?

Wood shredder blades last around 75 to 150 hours runtime before they need replacing.

What’s the difference between a chipper and a shredder?

The difference between a chipper and a shredder are, a chipper is designed to work on large pieces of wood and cut them into smaller pieces. A shredder either crushes or pulls apart branches and twigs making it much easier to compost.

How long does garden waste take to compost?

Garden waste can take as little as 6 months or as long as 24 months to decompose enough to be recognisable as soil. Having the correct mix will speed up the composting time.

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