The One Step You Might Be Forgetting After Sharpening Lawn Mower Blades

Sharpening lawnmower blades may not be everyone's idea of a fun time, but it's an important part of keeping your lawn in good condition. Blunt blades don't just leave a poor cut, they can actually damage the grass. It only needs to be done every 20 or 25 hours of run time, and the right sharpening tools will make it relatively quick and easy. However, there's one step many people overlook that can have a big impact on how your lawn mower cuts, and it has nothing to do with sharpness. It's a question of balance.

It's pretty obvious that the process of sharpening lawn mower blades removes metal from the cutting edges, and you probably think you're taking about the same amount off each. In practice, this is unlikely. Whether you realize it or not, it's almost certain you'll remove more metal from one side of the blade than the other. The difference may go unnoticed when you've got the blade off the machine, but when you put it back on — and it's spinning at a couple thousand rpm – there can be a noticeable increase in vibrations. This can affect the cut and make the machine uncomfortable to use, but more importantly, it will put additional strain on the blade shaft, bearings, and motor. Eventually, this could shorten your lawn mower's working life.

Fortunately, rebalancing lawn mower blades isn't difficult. There are a couple of ways to do it. First, you need a horizontal bar to hang the blade on (a screwdriver will do). Hold it in your hand or on the edge of a bench, and now slip the blade's center hole over the shaft so it can swing freely. If your blade is balanced, it will stay horizontal during this test. However, one end or the other may drop. If so, the end of the blade that's lower is heavier, so that's where material needs to be removed. Use whatever tool you were sharpening with, but don't be too aggressive. There's likely not a lot that needs to come off. Try the balance test again. Repeat until the blade is steady.

This method works, but it's slightly inaccurate because blades don't sit perfectly on the screwdriver shaft. The solution is a blade balancer like the one from Oregon that fits just about any lawn mower blade and allows you to balance your blades much more precisely. So while you've got the blade off, if you didn't do it already, now's a great time to clean your lawn mower from top to bottom. Scraping off dried grass and other gunk under the deck is a lot easier when the blade isn't in the way. There's a lot less chance of skinning your knuckles too!