Taking care of your teeth: instructions for sharpening your hedge trimmer

Hedge trimmer sharpening

Resin and thick branches blunt cutting blades over time. We explain how sharpening your hedge trimmer can be done quickly and easily.

How to tell if your hedge trimmer needs sharpening

Is your hedge trimmer no longer as effective as it used to be? This is not uncommon: frequent use blunts the cutter blades, so they need sharpening from time to time. It is possible that there is another reason for issues your trimmer may be having, so check the following symptoms to quickly deduce the likely cause:

Branches keep getting jammed in the trimmer

If you are noticing a tendency for branches to get stuck between the teeth during trimming, so they block the tool without being cut. This is a possible indication that the upper and lower blades of the hedge trimmer are no longer meeting, rather than an indication of a need for sharpening. This happens because the spacers between the blades wear out over time. Your dealer can fix this by replacing the spacers for you.

Branches are not cut cleanly

If your petrol or electric hedge trimmer leaves behind an uneven and frayed edge as it cuts, this indicates that you need to sharpen the hedge trimmer blades. You can go to one of our dealers for hedge trimmer sharpening, or alternatively you can get the tool back into peak condition - with some patience and a little effort, you can do this yourself.

You will need the following tools and materials to correctly sharpen your hedge trimmer:

  • Flat file
  • Whetstone
  • Soft cloth
  • Water
  • Resin solvent
  • Safety clothing
  • Work gloves
  • Safety glasses or face protection
A woman wearing protective gloves using a flat file and sharpening a hedge trimmer on a wooden workbench

Sharpening your hedge trimmer

Ideally, sharpening should be done before the blades show visible signs of wear – remember that the lifespan of your hedge trimmer is heavily dependent on regular maintenance. As such, we recommend sharpening after every 50 hours of use or so, to ensure consistent cutting performance and to enable you to enjoy your hedge trimmer for as long as possible. You can also find all the important information you need about sharpening your hedge trimmer in the operating instructions.

Important safety precautions:

Before you begin sharpening, think about how best to protect yourself. Wear safety glasses and gloves made from robust material to prevent injury. You should also ensure that your tool cannot accidentally start up or slip during sharpening.

Step 1: clean the teeth

During use, plant sap and resin accumulate on the cutting apparatus of your hedge trimmer. Remove this dirt with a soft cloth before you start sharpening the blades.

During use, plant sap and resin accumulate on the cutting apparatus of your hedge trimmer. Remove this dirt with a soft cloth before you start sharpening the blades

Step 2: sharpen your hedge trimmer blades with a flat file

With just a few steps needed for sharpening your hedge trimmer by hand, you can secure long-lasting cutting performance. First you’ll use a flat file.

  • Always file towards the cutting edge. The flat file is designed to work only when applied in one direction, and this method ensures a perfectly sharp blade.
  • When sharpening your hedge trimmer, try to use the file at the recommended sharpening angle, which is detailed under Technical Data in the operating instructions for your tool.
  • The file is only effective on the forward stroke, and so should be lifted from the surface when you move it back: avoid “sawing” back and forth on the surface with the file, as this may blunt the cutting edge again.
  • You should always be careful not to remove too much material during sharpening: the abrasion limit is 5 mm. If you file off more than this, the material strength may be compromised, rendering your hedge trimmer unusable.
  • Use the same number of file strokes for each cutting edge, so that all blades are the same length at the end.

Good to know: You should only sharpen the cutting edge of each tooth. Do not file the integrated cut protection or the orange plastic cut protection.

Close-up of a flat file being used to sharpen one blade of a hedge trimmer that overhangs a workbench, with gloved hands visible in the background

Step 3: remove burrs using a whetstone

You will need a whetstone for this step of sharpening. Use it to smooth any burrs that have developed on the underside of the blades during filing.

Turn the hedge trimmer over so that you can work on the back of the blades, and lightly moisten them as you work. Draw the whetstone along each blade, using a careful swiping motion in the direction of the tip and smoothing the roughened surface as you go.

Overhead close-up of several teeth on a hedge trimmer, with gloved hands using a whetstone to remove burrs

Step 4: care after sharpening

Almost done! Now you need to give your freshly sharpened hedge trimmer a little TLC.

First remove any grinding dust generated in the previous steps. The process of filing will have removed the corrosion protection that was previously on the blades, so you next need to spray the cutting apparatus with a suitable resin solvent. This will ensure that the machine continues to function perfectly and that it will serve you well for a long time to come.

A hedge trimmer is held up in one hand by a woman wearing gloves, who is spraying resin solvent onto the cutting apparatus with the other hand

When should I take my hedge trimmer to a professional?

If after reading this guide you feel unsure or uncomfortable it might be a better idea to take it to your local dealer. Not everyone is confident about sharpening tools themselves, and that’s OK. Also, if you are uncertain that dull blades are causing the issues your having it might be better to have a professional make an assessment. Our STIHL dealers will be pleased to help, and can professionally sharpen the blades to achieve an optimal result without removing too much material.

  • Sharpening is part of routine maintenance for your hedge trimmer
  • You should clean the blades before sharpening and moisten them before using the whetstone
  • A flat file is a good tool for sharpening
  • Burrs should be removed using a whetstone
  • Apply resin solvent to restore the corrosion protection

If you are uncertain about sharpening or need assistance, please contact one of our dealers.