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How to Sharpen Hedge Trimmers (2 Foolproof Methods)

Hedge Trimmer
Image Credit By: Mark Hunter, flickr

Tired of having to hack at bushes with your previously great hedge trimmer?

One of the most overlooked pieces of garden equipment maintenance is keeping trimmers sharp. Even the most expensive tool can feel like a useless burden if it’s not maintained properly. Since they go through so much wear-and-tear during normal use it’s important for any homeowner or landscaper to know how to sharpen hedge trimmers.

Let’s dive right in and we’ll show you two easy methods to get your trimmer ready to cut through just about anything.

A Quick Word About Trimmer Blades

Hedge Trimmer Blade
Image Credit By: Harisingh&sons, commons wikimedia

Hedge trimmers have a unique blade configuration, and many people aren’t even aware of how to sharpen them.

Each tooth has three surfaces that will need to be sharpened. The edges come down on both sides, of course, but there’s also the outer edges to surface to sharpen, which some people miss. You’ll also need to sharpen both the upper and lower portions. That’s six total surfaces per tooth.

They don’t need to be razor-sharp, think of them more like chisel blades. Indeed, getting a razor edge is undesirable since most of the dulling that occurs comes from chipping rather than warping and a thin edge will dull more quickly.

The exact geometry of the blades changes from tool to tool. The important thing is simply to maintain the existing angle. Removing the surface chipping to return a sharp, chisel-like edge is the goal.

Aligning the Blades Before Sharpening

Use a thick pair of gloves while sharpening to protect your fingers. The first thing to do after pulling on these gloves is to press the upper and lower blades together to align them as closely as possible.

This will get you most of the way there, but you want perfect alignment before you begin. Use a tool with a plastic handle like a screwdriver to wedge the blades together the final bit. Don’t use anything metal to pry the blades into place or you risk damaging the teeth.

Method #1: Using a Flat File

While a bit time consuming, the easiest way to sharpen the blades of a trimmer is with a large flat file. One which is 1-1 ½” across should do the trick, it just needs to be wider than the sides of the teeth.

We’ve found that this method is more intuitive for beginners since a hand-held file makes it easy to get the right angle. Just line it up with the existing angle of the tooth’s edge.

Only stroke in one direction with the file. If you bring the file back hoping to speed things up you’ll clog the tool quickly and in some cases ruin the file entirely.

Once the surface is nice and clean the blade should be sharp. The majority of dulling along the edges of trimmer blades comes from small chips that occur during normal use, usually from impacting thicker branches.

File on both sides of the teeth and the outer edge, then flip the trimmer over and do the same on the other edge.

Once all six surfaces have been filed back to sharpness you can move on to the next tooth and repeat the process down the length of the tool.

But when’s the best time to trim your hedges? – Click here to read our recommendations!

Method #2: Using a Grinder

A hand-held grinder can speed up the process but requires a bit more protective equipment and a lot more care.

An angle grinder is preferred but a die grinder or rotary tool with the appropriate bit can also be used

Anytime you’re using a grinder you’ll need the following:

  • Earplugs or earmuffs
  • ANSI-rated safety glasses
  • Heavy gloves

You’ll also find it much easier to get the job done if you use a C-clamp to hold the trimmer down to the work surface. Once the tool is clamped down securely you’re ready to go. Simply place the tool’s grinding surface at the existing angle and turn it on.

Hedge Trimmer with flowers
Image Credit By: Ben Grey, flickr

Use short strokes with the grinder, going back and forth. This is doubly important with smaller grinders as running the tool for too long in one spot can create an uneven surface.

Use very light pressure and make only two or three passes before checking the surface.

Once the surface has been ground move to the other two on the same tooth and repeat the process. The outer edge will often only require a few seconds of work since it’s smaller than the other two edges of the teeth.

Depending on where you clamped the trimmer, it may be easier to grind every tooth that’s overhanging the work surface before flipping it over and repeating the process.

For the last few trimmer teeth, you may need to clamp on the motor housing or handle. Just ensure the tool is completely secure before taking the grinder to it. Once you’ve worked each tooth you’ll have a nice and sharp trimmer for your next bush-cutting chore.

Sharp Teeth, Short Work

Hedge trimmers are a major time saver in the garden but dull blades can make them feel like more effort than they’re worth. Learning how to sharpen hedge trimmers will save you a ton of frustration in the long run and it’s very simple once you’ve got the hang of it.

Either method works great, just find the maintenance method that works best for you and get to it!

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