Here’s How to Sharpen or Replace a Rotary Lawn Mower Blade

Keep your lawn looking cutting edge.
Well-sharpened blades ensure clean, smooth cuts to keep your grass healthy and strong. Here’s how to sharpen your gas or electric rotary mower blades.

What You'll Need

Work Gloves

Cleaning Rags

Eye Protection

Scraper

Vise

Socket Wrench

Power Drill

Sharpening Stone

Steps

Step 1: Get Set Up
Disconnect from the power source (disconnect the spark plug wire for a gas mower). Wearing work gloves, flip the mower over and use the socket wrench to remove the blade mounting nuts.

Step 2: Clean & Assess the Blade
Remove the rotary blade and clean it with a scraper and rags. If the blade is nicked or damaged, purchase a replacement and skip to step 5. If not, it is ready for resharpening.

Step 3: Sharpen the Blade
Clamp the blade in a vise, cutting side up. Put the sharpening stone attachment onto your drill, and – wearing eye protection – use the stone to sharpen the blade.

Step 4: Balance the Blade
Check if the blade is balanced. Use a blade balancer, or hang it from its centre hole on the wall. If unbalanced, return to the vise and remove extra weight from the blade’s non-cutting side, until balanced.

Step 5: Reinstall the Blade
Wipe down and then reinstall the blade. Reconnect the spark plug wire (gas) or battery pack (cordless electric). Or plug in your mower if it is a corded electric model.

Step 6: Start Mowing
Mow your lawn, taking pride in the great results. Blade sharpening can be done once or twice during the season, or anytime after your mower encounters a hard surface.

Good to Know

• The blade on a manual reel lawn mower is more complicated to sharpen. For best results, take your reel mower in for professional sharpening.
• For larger lawns, consider a ride-on lawn mower or lawn tractor, which can cover more ground in less time.