How to Replace a Lawnmower Blade - Bosch

If you've noticed your grass isn't cutting as evenly as it should or is still patchy after mowing, it could be down to a worn or chipped lawnmower blade. Over the summer months, the blade can become blunt due to lots of use or get chipped or damaged from coming into contact with pebbles and stones.

Not to worry though, because lawnmower blades can be easily replaced and in this article, we're going to show you how to replace the blade on a Bosch lawnmower.

If you're looking for advice on how to replace the blade on a Flymo lawnmower, take a look at our article for a guide on the process for these models.

We also have an article showing you how to replace a Qualcast blade on a Classic Petrol 35s lawnmower if this is the kind of lawnmower you own instead.

To find out how to fit a new blade on a Bosch lawnmower, take a look at the video or follow the guide below. We will be demonstrating how to do this on a Bosch Rotak 40 lawnmower but the process should be pretty much the same for most rotary lawnmowers in the Bosch group.

Before you begin carrying out any work on your appliance, make sure it is switched off and fully disconnected from the mains.

To complete this repair, you'll need to have the following items:

• A spanner
• A screwdriver, cloth or pair of protective gloves
• A replacement lawnmower blade

To make sure you purchase the correct replacement blade for your lawnmower, you'll need to know the model number. This is displayed on either a sticker or data plate and can usually be found on the back or underside of your lawnmower or on the chassis or grass box. For help on where to find the model number or what to do if yours has rubbed off, take a look at our article.

The blade on the lawnmower cannot be unscrewed because it is attached to the motor spindle behind. What you need to do is hold the blade in place while you unscrew the central locking nut. You can either do this by holding the blade in place with a cloth or whilst wearing protective gloves to keep your hands safe while you unscrew the nut...

Or, you can place a screwdriver in the hole above the blade which will hold it in place while you unscrew the nut.

As you will see, there is a big difference in the sharpness of the edges of the new blade and the old blade.

To fit the new blade, take the central locking nut and pass it through the middle hole of the new blade.

Make sure that the bearing cover is still in place and screw the blade into position.

For the final couple of turns, make sure you either place the screwdriver in the above hole to keep the blade in position or hold it with a cloth so you can tighten the locking nut. 

And that's how simple it is to replace a blunt lawnmower blade to get your appliance back up and running and your grass even again!

If, while replacing the blade, you find that your lawnmower is becoming clogged with grass and debris, it's probably in need of a good clean to keep it working to its best! Take a look at our article for a guide on the best way to clean your lawnmower.

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