Better Blade Sharpening

How often to sharpen blades, how to do it, and what to do it with.

Dealership technician sharpening lawnmower blades with a powered handheld grinder. Some still prefer this method.
Dealership technician sharpening lawnmower blades with a powered handheld grinder. Some still prefer this method.

An important step to quality mowing and overall grass health is keeping your mower blades sharp. Quality-minded lawn maintenance professionals take this very seriously.

For example, Shane DeVoe of DeVoe Enterprises in Parkesburg, PA, sharpens his blades every other day. "We sharpen them first thing in the morning when the mowers are still cool," DeVoe points out. "Right now we're using a bench grinder, but are considering buying a dedicated blade grinder to save a little more time."

Adam Mahon, owner of Mahon Property Maintenance in Louisville, KY, changes his blades daily during the spring and early summer, backing off to every other day during the summer and just twice a week during slow periods. "We have a dedicated sharpener for blades, but I've found that our (handheld) angle grinder, although slower, keeps the angle better so the blades cut better and longer," Mahon relates.

Tim Emick, owner of Timberline Landscaping in Colorado Springs, CO, says his mow crews put freshly sharpened blades on every one of their mowers every night. The blades that come off are then sharpened with a stationary grinder and balanced with a specialized blade balancer—as opposed to a nail in the wall or screwdriver in a bench vise.

As you can see, there are several approaches a contractor or servicing dealer can take—and tools he can use—to sharpen and balance mower blades. Whichever method you choose, it's important to consider complexity, efficiency, reliability and consistency.

It's all about the angle

When sharpening a mower blade, you must pay attention to the angle of the cutting edge. As mower manufacturer Toro points out in a service tip on its website, always grind the top surface of the blade only—maintaining the angle of the original cutting edge.

Gerd Bauer, vice president of Magna-Matic, a manufacturer of blade-sharpening tools, says that by consistently grinding the same angle, you gain efficiency and get the most life out of a blade. You also improve safety, because a blade will be less likely to fracture due to excessive steel removal.

Furthermore, it's also critical to consider how your mower blade is actually cutting the grass. "The first 1-2 inches of the blade do the majority of the cutting and take the most wear," Bauer explains. Thus, this area is where the most grinding is required to reproduce a good cutting tip. Some people are insistent on grinding the full cutting edge until it is parallel to the rest of the blade. But this isn't necessary, Bauer says, and can actually be detrimental (see illustration).

Some specialized blade sharpeners can assist you in achieving blade-sharpening perfection. They make it easy to dial in different angles and overall improve efficiency and finish quality. For most standard mower blades, 30° is what you're shooting for. Curved mulching blades can get tricky. As a general rule, always consult your owner's manual.


Magna-Matic Blade Sharpeners are offered in two models. The MAG-9000 is ideal for conventional flat/straight blades, allowing you to dial in a consistent 30° The MAG-8000 is ideal for both conventional flat/straight blades and curved mulching blades, allowing you to dial in a 25-45° angle in 5° increments. Visit for more information.

Oregon says its Heavy-Duty Blade Grinder is quick and easy to adjust, making it ideal for servicing dealers, landscape contractors and even do-it-yourselfers. Visit for more information.

Rotary offers a variety of blade sharpeners and grinders for all types of mulching or standard mower blades. Included are Wall and Neary models plus an array of ruby and grinding stones, blade balancers and supplies. The Wall RBG 712 Sharpener/Grinder restores blades to a factory flat edge using a preset blade guide to maintain proper angles. Visit for more information.

Work Sharp's Work Sharp Knife & Tool Sharpener Ken Onion Edition features a fully adjustable precision sharpening guide (15-30° in 1° increments), variable speed control, and grinding attachment for more efficient mower blade sharpening. Visit for more information.