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Lawnmower Blade Sharpening

Posted by Mr Mower Parts on 2/10/2013
Lawnmower Blade Sharpening

Get your lawnmower ready for spring with a blade sharpening. A dull blade will rip the grass and damage it rather than cut it cleanly and allow it to grow healthier. Sharpening a blade is easy to do with a few simple tools. Here are the steps.

1) Disconnect the sparkplug wire from the sparkplug. You don't want any possible way for the lawnmower engine to start or the blade to jerk on a power stroke while your working underneath.

2) Place newspapers or old rags on the ground and then flip the lawnmower on its side on top of the papers or rags. The papers or rags are there to absorb any fluid that leaks out. Flip the lawnmower with carburetor in the air to prevent white smoke from coming out of the engine when you restart it later.

3) Clean off a bottom section of the blade with a putty knife and then mark it with the word "Bottom". Use a marker or paint pen.
One of the biggest mistakes people make is installing the blade upside down and then can't figure out why it won't cut grass properly.

4) Remove the blade by loosening the bolt that holds it in place. The bolt will be really tight so you will probably need a long wrench or breaker bar and socket to get it off.

5) Check the blade for excessive wear and lay it on a flat table to see if one side sticks up higher than the other. This will indicate the blade is bent. If it's bent or worn too far, then a new blade is needed. You can get new blades right here at

6) Clamp the blade in a vise and then use a file to sharpen the cutting edge. This can take a while so a blade sharpener mounted in a drill will make the job go quicker.

7) After you have the blade sharp, you need to make sure its balanced. A balance tool makes this easy. Just put the cone inside the blade mounting hole and check for balance. If one side is lower than the other then sharpen the lower side a little more to make that side lighter. Continue this until the blade is balanced.

Cone Blade Balance tool

8) Reinstall the blade and tighten the bolt per the torque specs in your lawnmower manual. It should be around 50-70 ft-lbs. You want it tight without stripping the threads. A torque wrench is very handy to make sure you get this right.

That's it. Your ready to cut your grass with a sharp blade. You should sharpen the blade twice per cutting season. It makes it easier to have a second blade on hand so you can just swap them and sharpen later. has most blades in stock ready to ship.