Do this 2-3 times if your blades are especially dirty. You can do this before or after you sharpen the blades.

How often you need to sharpen your hedge trimmers depends entirely on how often you use them. Most people find that they need to sharpen the trimmers after roughly 50 hours of use.

It’s especially important to wear protective eye gear if you’re going to use a rotary tool to sharpen the blades, since this is likely to send a spark or two flying.

This also allows you to sharpen both sides of your blade trimmer at the same time if you’re going to use a rotary tool. If you have a mechanism on your hedge trimmer that allows you to lock the blades in place, lock the blades now. If you don’t, steady the blade with one hand while filing with the other.

If you don’t have a clamp for your hedge trimmer, you can pin it underneath something incredibly heavy—like a bag of concrete. You cannot sharpen the blades without keeping the trimmer still, though.

The bevel refers to the sharp, angled edge of a blade.

If you drag the file back and forth in two different directions, you’re just going to wear down the blade’s tooth and make it dull. Work in the same direction.

This may take anywhere from 30 minutes to an hour.

This is entirely optional. Your trimmer will still cut just fine without the whetstone, but you’ll get a much cleaner cut by removing burrs, which may be ideal if you’re doing any cosmetic landscaping.

Rotary tools are often called Dremel tools. Dremel is the name brand of the biggest rotary tool manufacturer. The flat tip should be perfectly flat and even on each of its sides, like a symmetrical cylinder. Don’t use a rounded tip that resembles a bullet, since these will catch on the bevel. If you plan on sharpening your trimmers regularly, the rotary tool is a good investment. This is much easier than using a file. Some people will use an angle grinder instead of a rotary tool to do this. Unfortunately, this is a very unwieldy and dangerous way to sharpen the blades. You’re much better off using a smaller rotary tool.

Move the bit back and forth for 3-5 seconds. Don’t apply any pressure or push the bit into the blade. Let the rotary tool do the work for you. The edge of the tooth may change color a bit as you wear away any rust, dirt, or worn-down metal. If the tooth does change color, you’re done.

This entire process shouldn’t take more than a few minutes.