With proper maintenance and care, a quality lawn mower can provide reliable service for a decade or more. A key part of that maintenance is learning how do you sharpen a reel lawn mower blade. A sharp reel and bedknife are essential for a clean, healthy cut, and doing it yourself saves money and extends your mower’s life.
This guide provides clear, step-by-step instructions. We’ll cover the tools you need, safety precautions, and the sharpening process itself. You’ll also learn how to check your work and adjust the mower for perfect performance.
How Do You Sharpen A Reel Lawn Mower Blade
Sharpening a reel mower is different from sharpening a rotary mower blade. Instead of a single spinning blade, you have a cylindrical reel with multiple helical blades that spin against a stationary bedknife. The goal is to create a precise scissor-like cutting action between the two.
Before you start, gather the right equipment. Having everything on hand makes the job smoother and safer.
Essential Tools And Safety Equipment
You don’t need a professional shop, but a few specific tools are required. Safety is paramount when handling sharp metal components.
Required Sharpening Tools
- Reel mower sharpening kit (lapping compound and backlapping tool) or a dedicated reel grinder.
- A set of feeler gauges for measuring clearance.
- Adjustable wrench or socket set for removing the reel.
- A clean, flat work surface like a sturdy bench.
- Degreaser and clean rags.
- A marker or machinist’s dye (optional, for visual aid).
Critical Safety Gear
- Heavy-duty work gloves to protect your hands from sharp edges.
- Safety glasses or goggles to shield your eyes from metal particles and compound.
- Sturdy, closed-toe shoes.
Step-By-Step Sharpening Process
Follow these steps in order for the best results. Rushing or skipping steps can lead to a poor cut or damage to the mower.
Step 1: Preparation And Removal
First, disconnect the spark plug wire on gas mowers or remove the battery from electric models to prevent any accidental starts. Tip the mower onto its side, preferably on a soft surface like grass, with the reel and bedknife facing up. Clean the entire cutting assembly thoroughly with degreaser to remove all grass, dirt, and old oil. This gives you a clean surface to work on and prevents contamination of your sharpening compound.
Step 2: Checking The Current Condition
Before sharpening, assess the reel and bedknife. Spin the reel by hand and look for nicks, dents, or sections that look visibly dull. Check the bedknife for wear or grooves. Lightly touch the edges with your gloved hand to feel for burrs. If the reel blades are deeply nicked or the bedknife is worn unevenly, professional regrinding might be necessary. For routine annual maintence, backlapping is usually sufficient.
Step 3: Adjusting The Bedknife
Proper alignment is crucial. The bedknife must be parallel to the reel along its entire length. Loosen the bedknife mounting bolts slightly. Using your feeler gauges, check the clearance between the reel blades and the bedknife at both ends and in the middle. The gap should be consistent, typically the thickness of a piece of paper (about 0.001-0.003 inches). Tighten the bolts carefully while maintaining this paralell alignment.
Step 4: Applying Compound And Backlapping
This is the core sharpening method for most homeowners. Apply a generous strip of coarse-grit lapping compound along the entire length of the bedknife. Attach the backlapping handle to the reel axle. Slowly turn the reel backwards against its normal rotation. This draws the reel blades across the bedknife, with the abrasive compound in between, honing both edges.
- Turn the reel backwards for 30-40 revolutions.
- Wipe away the used, blackened compound with a rag.
- Apply a strip of fine-grit lapping compound.
- Turn the reel backwards for another 20-30 revolutions.
This two-stage process hones a fine, sharp edge. The reel should turn smoothly with light resistance.
Step 5: Final Testing And Reassembly
Clean off all traces of lapping compound with degreaser and a rag. Perform the “paper test.” Hold a strip of newspaper against the bedknife and spin the reel forward. A sharp mower will cleanly slice the paper. Reconnect the reel drive mechanism if you disconnected it, and carefully lower the mower back onto its wheels. Reconnect the spark plug or battery.
Common Mistakes To Avoid
Even with good instructions, it’s easy to make errors. Being aware of these common pitfalls will help you achieve a professional result.
- Over-tightening the bedknife bolts, which can warp or crack it.
- Using the wrong type of abrasive compound. Always use lapping compound designed for reel mowers.
- Turning the reel too fast during backlapping. A slow, steady pace allows the compound to work effectively.
- Failing to clean off all the compound after sharpening, which leads to accelerated wear.
- Neglecting to check the reel bearing for play before sharpening. Worn bearings will ruin your alignment.
When To Seek Professional Service
While DIY sharpening is rewarding, some situations call for a pro. If your reel has significant flat spots, deep grooves, or bent blades, a specialized reel grinder is needed to restore the cylindrical profile. Similarly, a badly worn bedknife may need to be replaced or reground by a machine shop. If you’ve followed the steps but the mower still tears grass, professional help can diagnose and fix underlying mechanical issues.
Maintaining Your Sharpened Blade
After sharpening, a little regular care keeps the edge longer. Always clean the underside of the mower after each use to prevent grass buildup. Before storing for the winter, apply a light coat of oil to the reel and bedknife to prevent rust. Check the cutting adjustment periodically throughout the mowing season, as vibration can cause it to change. Avoid mowing over sticks, stones, or hard debris, which are the primary causes of nicks and dulling.
Frequently Asked Questions
How Often Should I Sharpen My Reel Mower Blades?
For an average residential lawn, plan to sharpen your reel mower once per mowing season. If you have a very large lawn or mow frequently, you might need to do it twice. The best indicator is performance; if the mower starts tearing grass instead of cutting it cleanly, it’s time.
Can I Use A File Or Grinder To Sharpen A Reel Mower?
Using a hand file or angle grinder on the individual reel blades is not recommended. It’s extremely difficult to maintain the correct helical curvature and angle. This method often ruins the reel’s geometry. Backlapping with compound is the safe, effective DIY method.
What Is The Difference Between Sharpening And Lapping?
In reel mower context, “lapping” (or backlapping) is the primary sharpening technique for homeowners. It uses abrasive compound to simultaneously hone both the reel and the bedknife. “Sharpening” sometimes refers to machine grinding, which removes more metal to correct major damage or wear.
Why Does My Reel Mower Still Cut Poorly After Sharpening?
Poor cutting after sharpening usually points to incorrect adjustment. The most likely culprit is the bedknife-to-reel clearance being too large. Re-check the gap with a feeler gauge. Also, ensure the reel bearings are not worn, allowing the reel to wobble instead of spinning true.