How to Sharpen Loppers and Garden Pruners at Home

How to Sharpen Loppers, Step by Step

To sharpen loppers, clean the blades, lay a file on the beveled edge at the angle already ground into it (normally 10 to 20 degrees), and draw the file from the pivot toward the tip in one direction. Ten to twenty draws restore a blade that has been looked after. Finish with a few flat passes on the back to remove the burr, then oil the metal. Hand pruners are sharpened the same way with a smaller file, and a pair in fair condition takes about 10 minutes.

1. Clean. Scrub the blades with warm, soapy water and a scouring pad, then dry them with a rag.
2. Find the bevel. Open the loppers and look for the slanted, shiny strip along the cutting edge. That strip is the only surface you file on a bypass tool.
3. Set the angle. Hold the file flat on the bevel. The correct angle is the one already there, normally between 10 and 20 degrees.
4. File in one direction. Start at the inside of the blade near the pivot. With moderate pressure, draw the file toward the tip in a curve that follows the blade. Lift it, return, and repeat. Count 10 to 20 draws for a well-kept blade and 40 to 50 for a neglected one.
5. Remove the burr. Run a fine file over the back of the blade a few times, held flat.
6. Test and oil. Hold the edge up to a light, make a test cut, and wipe on a thin coat of lubricant.

Each step is explained below, along with what changes for anvil tools and when to take the tool apart.

Bypass or Anvil: Which Side to Sharpen

Look at how the blades meet before you file anything. Bypass loppers and pruners work like scissors with one sharp blade: a curved cutting blade slides past a thicker hook. Kansas State University Extension says this type should be sharpened on the side away from the curved hook, and that sharpening both sides damages the blade. The flat inner face has to stay flat so it rides tight against the hook. A gap there lets green stems fold between the blades.

Anvil tools have a thin, sharp blade that closes onto a blunt bar. Only the sharp blade needs sharpening, never the anvil. Follow whatever bevel the maker ground onto it, and keep the edge straight, because sharpening must be uniform for the cutting edge and the anvil to meet at every point. A hollow filed into the middle of the blade leaves a strip of bark uncut.

A few loppers and shears have two cutting edges. Sharpen both. Bypass vs. anvil pruners explains which design suits which job.

Clean Off Sap and Rust First

Blades stick when the cutting surfaces are grimy, and a file works poorly through a layer of sap, so cleaning comes before sharpening. Warm, soapy water and a scouring pad or scrubby sponge remove most of it. For hardened sap, use a solvent such as mineral spirits on a rag.

Rust comes next. Coarse steel wool takes it off, and fine steel wool brings back the sheen of the metal. For a badly rusted pair, University of New Hampshire Extension suggests applying a penetrating oil spray, letting it soak for 10 minutes, wiping it off with a clean cloth, and then using steel wool on what remains. Heavier cases are covered in removing rust from garden tools.

If your pruners or loppers come apart with one pivot bolt, take them apart. A detached blade is much easier to clean and sharpen. Take a photo before you start and lay the parts out in order, since the washers and spring only go back one way. Tools with riveted pivots stay assembled, and you work with the jaws open as wide as they go.

The Sharpening Stroke in Detail

A diamond file is the simplest tool for hand pruners. For loppers, with their longer and thicker blades, a mill file also works, and so does a whetstone if the blade is off the tool. Start with a coarse surface and move to finer ones. Patting a metal file with a moist cloth keeps it from clogging with filings, and a whetstone should be wetted thoroughly with water or light oil before use. Pick one and stay with it. Do not switch between water and oil on the same stone.

Brace the tool so it cannot move. Loppers have long handles that swing, so clamp one handle in a vise or pin it against a bench with a gloved hand, and keep the hand holding the file behind the edge.

Hold the file at the bevel angle and push or draw it along the edge in one smooth pass from the inside of the blade to the tip. Sharpen in one direction only. Kansas State warns that pulling a file backward under pressure bends its teeth and can permanently damage it. For a well-maintained blade, 10 to 20 draws should be enough. A poorly maintained one needs about 40 to 50 passes. Then repeat with the fine file and the extra-fine file, using the same number of passes each time.

A nick from cutting wire or hitting a stake needs the coarse file until it is gone. Do not chase a razor edge on a lopper. Kansas State advises against reducing the beveled edge to less than 1 mm thick, because a finer edge does not cut better and is more fragile.

Finish on the back. Filing raises a thin wire of metal, the burr, along the flat side. Remove it with a light, flat stroke of a fine file, whetstone or sandpaper along the back of the cutting edge.

Test the Edge

Hold the cutting edge up to a light source. A dull spot reflects light as a bright line, and a sharp edge shows nothing. If light reflects off the edge, go back to the fine file for a few more strokes.

Then cut. A sheet of paper is a fair test for hand pruners: a clean slice means the blade is sharp enough. For loppers, try a branch of the right size for the tool. The cut should be easy and clean. A blade that pulls or catches needs more work.

Size matters for the test and for the life of the edge. Hand pruners are made for branches up to 1 inch in diameter, and loppers handle branches up to 3 inches. Forcing a tool through wood beyond its range is how edges get nicked and blades get sprung. Choosing pruning shears covers matching the tool to the branch.

Disinfect the Blades

Sharp blades make clean wounds, but they can still carry disease from plant to plant. University of Wisconsin Extension recommends treating tools for at least 30 seconds with 10 percent bleach or, preferably, 70 percent alcohol, which is less corrosive. Rubbing alcohol can simply be wiped on or used as a dip, with no long soak.

Bleach is the cheaper option with more drawbacks. The mix is one part bleach to nine parts water. University of Missouri guidance for orchard tools calls for a 30-minute soak, notes that the solution is 50 percent less effective after two hours, and so it has to be mixed fresh. Rinse bleach from tools afterward, because it is corrosive to metal.

When you are removing diseased wood, clean the blades between pruning cuts. Our guide to fire blight on fruit trees covers one disease where this step applies. Carry a small bottle of 70 percent alcohol and a rag in your pocket so the step is quick enough to do every time.

Oil, Reassemble and Store

After sharpening, apply a light lubricant to the blades and the pivot. It repels water and hinders rust, and it keeps the action smooth. Wipe off the excess with a clean rag. Lightly coat the blades a few more times through the year.

Reassemble using your photo. Tighten the pivot until the blades pass with no sideways play and the tool still opens freely. On bypass loppers, close the blades slowly and check that the cutting blade touches the hook along its whole length.

Store pruners and loppers in a clean, dry place. Loppers with wooden handles benefit from the care described in wooden tool handles, and storing garden tools for winter covers the end-of-season routine.

How Often to Sharpen

Use sets the schedule. Well-maintained pruners need sharpening only about every six weeks, even with heavy use. A gardener who prunes around 4 hours a week may need to sharpen once or twice a year. Between sharpenings, wipe sap off after each session so it never hardens.

A practical calendar is one full sharpening before dormant pruning begins, since late winter pruning is when loppers do their heaviest work, and a second in fall before storage. Sharpen sooner if stems start to tear or crush, or if you need both hands on pruners for a cut that used to take one.

Quick recap

• File only the beveled side of a bypass blade, at the existing angle of about 10 to 20 degrees, in one direction from pivot to tip.
• Count 10 to 20 draws for a maintained blade and 40 to 50 for a neglected one, then remove the burr with a flat pass on the back.
• Clean first with soapy water, mineral spirits for sap and steel wool for rust.
• Disinfect for at least 30 seconds with 70 percent alcohol, or use bleach mixed one to nine and rinse it off.
• Oil the blades, set the pivot with no side play, and sharpen about every six weeks under heavy use.