How to Backlap a Reel Mower at Home Step by Step

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Backlapping reel mower blades means turning the cutting reel backward while you apply a fine abrasive compound, so the blades grind lightly against the bed knife and regain a sharp edge. You do it with the mower secured, the reel spinning in reverse and compound spread evenly across the blades. The process does not replace grinding: if the blades stay dull after several rounds of backlapping, the source below says the edges need grinding instead. This guide follows the steps in a published reel mower guide from Foley, and it names the compound and accessory products from our product data that are used for the job.

Quick answer

Secure the mower on a stable surface, turn the reel backward, and spread compound evenly across the blades with a brush or spatula.
Run the reel in reverse for about 2 to 5 minutes, check the edge, and reapply compound if the blades still look dull.
Start with a coarse 80 grit compound if the blades are very dull, then finish with 120 grit. Medium 120 grit is the usual choice for routine upkeep.
If about 5 to 7 minutes of backlapping does not improve the cut, stop and have the reel ground, since more backlapping will not fix it.

What you need

Backlapping requires three things: a way to turn the reel in reverse, an abrasive compound, and a brush or applicator. Reel mowers differ in how the reel is driven in reverse. Some have a backlapping function, and others need a crank or a drill-driven adapter that fits the sprocket. The Foley guide says that if your mower has a backlapping function, you should engage it, and if not, you should adjust the settings so the reel spins in reverse. Check your mower’s manual for the exact method before you start.

For the compound, the product data includes several options. The B1LC12011 is an 11 lb tub of 120 grit medium compound that the listing describes as a backlapping compound for reel and cylinder mowers. The Reel Lawn Mower Backlapping Sharpening Compound Kit includes a 1.5 lb total of 80 grit and 120 grit paste, plus protective gloves and an application brush. The huzile 2-piece kit combines an 80 grit and a 120 grit compound with gloves and a brush. The 80 Grit Homeowners Reel Sharpening Starter is a pre-mixed 80 grit paste with an application brush. A 2-pack of 120 grit lapping compound comes in two 100 g containers.

The backlapping adapter for the McLane sprocket is a third-party accessory. Its listing says it fits onto the reel mower’s sprocket and lets you run the reel backward without removing the cutting assembly. Use it only if your mower’s sprocket matches the listing’s model reference. For safety, the CGAP reel mower backlapping sign is a sign for a workshop or maintenance bench, not a tool, and it is listed for golf course maintenance.

Step 1: Prepare the mower

Put the mower on a stable, level surface where it cannot roll. The Foley guide says to secure the mower before you work on it. Make sure the mower cannot start or move while you work, and keep the drive disengaged. If the mower has an engine or motor, follow the manufacturer’s steps for disabling it before you work near the reel. Clean the reel and bed knife of grass and debris, since any stone or dirt will scratch the blades during backlapping.

Step 2: Set the bed knife and reel

Before you apply compound, set the reel so the blades do not press hard against the bed knife. The Foley guide says to aim for light, even contact, and warns against over-tightening the reel against the bed knife, because that speeds wear and adds friction. The guide does not describe the exact clearance procedure, so the mower’s manual is the place to get the adjustment steps for your model. Many reel mowers have adjustment screws or jam nuts on the reel shafts, and you should tighten those only after the contact is set.

Step 3: Apply the compound

Spread the compound evenly across the reel blades with a brush, a spatula or a paint stick. The Foley guide says not to over-apply, since too much compound can sharpen unevenly. The huzile listing says its kit includes a long-handled applicator brush, which is useful for reaching the reel from the side of the mower. Work the compound into the blades so each blade has a thin, even coat. Do not let the compound pool on the bed knife or the frame, and keep it off your skin.

Step 4: Run the reel in reverse

Spin the reel at a moderate speed in reverse for 2 to 5 minutes. The Foley guide says to check periodically during the run. If the blades still look dull after the first run, stop the reel, reapply compound, and run it for another 2 to 3 minutes. The huzile listing describes turning a hand crank in the opposite direction, which is the same reverse-spin principle, although the listing’s own instructions are on the product page, and you should read them before use.

Keep your hands, tools and clothing away from the reel while it turns. Reel blades are sharp even when they are dull, and a hand that slips can be cut. The CGAP sign in our product data warns of exactly this risk during backlapping, and it is a sensible reminder to keep hands out of the cutting reel at all times.

Step 5: Check the edge with a paper test

Stop the reel and test the edge. The Foley guide describes a paper test: pull a thin strip of paper or a blade of grass through the cut, and the reel should cut it cleanly across its full width. A torn or ragged cut at any point means the blades still need work. Check the edge at both ends and in the middle, since uneven wear is common, and note which parts still tear. If the edge is clean across the width, the reel is ready for the final step.

Step 6: Rinse off the compound

Rinse all compound off the reel and bed knife with water. The Foley guide says to use a degreaser if the compound is oil-based. The water-soluble pastes in several listings in our product data are designed to rinse off with water, but you should still check the label on the compound you bought. Leftover compound can cause wear once the mower is back in use, so clean the reel thoroughly and dry it before you run the mower.

Step 7: Set contact and test cut

After cleaning, set the bed knife contact again so the reel just touches the bed knife with light, even pressure. Tighten the adjustment nuts only when the setting is right. Then run the mower over a small test patch. The Foley guide says ragged or torn turf means further adjustment or grinding may be needed. A smooth, quiet cut across the patch means the backlap has worked.

When to stop and grind instead

Backlapping only refines the edge. If the blades are badly rounded or nicked, the Foley guide says that about 5 to 7 minutes of backlapping without noticeable improvement signals that grinding is needed. Continuing past that point is ineffective and can cause excessive wear. Grinding removes more metal and should be done by someone who knows how to set the reel and bed knife for grinding, so take the mower to a service shop if you are unsure.

Choosing a grit

Grit describes how coarse the compound is. The Foley guide gives these ranges: 80 grit is coarse and suits significant dullness or minor imperfections, though it leaves a rougher finish; 120 grit is medium and is the most common choice for routine backlapping and for maintaining sharpness between grinds; 180 to 220 grit is fine and suits finishing after a coarser grit; and 280 grit or finer is rarely needed. For most homeowners, start with 80 grit only if the blades are noticeably dull, then finish with 120 grit. For regular upkeep, 120 grit alone is usually enough.

The product data includes compounds at both grits. The 2-pack of 120 grit lapping compound and the 11 lb 120 grit tub are the medium options. The 80 grit starter and the combined kits suit the coarser start. A combined kit lets you do both steps with one purchase.

Common mistakes

Applying too much compound. The Foley guide says it can sharpen unevenly.
Running the reel forward. Backlapping only works in reverse, and forward spinning will not sharpen the edge.
Over-tightening the reel against the bed knife. This speeds wear and adds friction.
Continuing past 5 to 7 minutes without improvement. Stop and grind instead.
Skipping the cleanup. Leftover compound can cause wear once the mower is back in use.
Working with the mower unsecured or able to start. Secure it and keep the drive disengaged first.

Safety

The Foley guide advises wearing protective gloves and safety glasses, securing the mower before you work on it, and cleaning all compound off afterward. The reel is sharp, and it can cut a hand that slips into it. Work with the mower stable, keep your hands clear of the reel while it turns, and stop the reel before you check the edge with your fingers. If you are maintaining a mower in a workplace, the CGAP sign in our product data is a reminder to post near the work area.

FAQ

How often should I backlap a reel mower?

The Foley guide does not give a fixed schedule. Backlap when the cut starts to look ragged or the mower tears the grass, and check the paper test at the start of each mowing season. A dull reel that tears grass needs attention before the grass grows tall.

Can I backlap without removing the reel?

Some reel mowers have a backlapping function, and the backlapping adapter in our product data is described as letting you backlap without removing the cutting assembly. Check your mower’s manual, since the method depends on the model.

Which grit should I buy first?

Buy a 120 grit compound for routine upkeep. If your blades are noticeably dull, start with 80 grit and then finish with 120 grit, which is what the combined kits in our product data are designed for.

How do I know when the reel is sharp enough?

Use the paper test. The reel should cut a strip of paper or a blade of grass cleanly across its full width. Ragged or torn cuts mean the blades still need work.

What if backlapping does not help?

If about 5 to 7 minutes of backlapping does not improve the cut, the Foley guide says the reel needs grinding. Stop backlapping, since more time will not fix a badly worn edge.

Do I need to rinse the compound off?

Yes. Rinse all compound off the reel and bed knife after backlapping. Use a degreaser if your compound is oil-based, and check the product label for the right cleanup method.

Bottom line

Backlapping is a reasonable home job for a reel mower with a dull edge that is not badly damaged. Use 80 grit only if the blades are very dull, finish with 120 grit, run the reel in reverse for short periods with a paper test between runs, and stop after about 5 to 7 minutes if the cut does not improve. Set the contact light, clean off the compound and test the cut. If the blades are badly worn, grinding is the next step.

Products named in this guide

Each product below is listed in our product data for this topic. Check the listing for the full details before you buy.

Reliable Aftermarket Parts B1LC12011, 11 lb 120 grit reel diamond backlapping compound: View on Amazon
Reel lawn mower backlapping sharpening compound kit, 1.5 lb total with 80 and 120 grit: View on Amazon
huzile 2-piece reel lawn mower sharpening kit with 80 and 120 grit: View on Amazon
80 grit homeowners reel sharpening starter with application brush: View on Amazon
120 grit reel mower sharpening compound, 2 pack of 100 g containers: View on Amazon
Backlapping adapter for a McLane reel mower sprocket, third-party accessory: View on Amazon

Sources

The Ultimate Guide to Backlapping Reel Mowers, Foley

For more on blade types and reel mowers, see the guide to replacement mower blades and the reel and robot mowers listed beside them, and the guide to blade styles for lawn mowers.