Tree loppers are designed with long handles to provide leverage for cutting thicker branches that hand pruners cannot manage. These tools typically feature hardened steel blades that perform a scissor-like action, creating a clean transection in wood up to about two inches in diameter. Regular maintenance, particularly sharpening, is necessary because a dull blade requires more force, increasing strain on the user and causing ragged cuts on the plant material. A clean, sharp cut is important for plant health, as it allows the wound to seal quickly, reducing the opportunity for disease pathogens to enter the exposed tissue. Keeping the blades sharp improves cutting efficiency and prolongs the tool’s life.
Required Tools and Safety Preparation
Before beginning the sharpening process, gather all necessary materials. The required tools include a suitable sharpening file or stone, such as a medium-grit diamond file or a mill bastard file, along with rags, a cleaning solvent, and a lubricating oil. Essential safety gear, like heavy-duty work gloves and eye protection, should be worn at all times to guard against sharp edges and metal shavings.
Thoroughly cleaning the loppers removes accumulated plant sap, dirt, and rust. Sap contains sticky resins that can harden and inhibit the sharpening process, so it should be dissolved using a solvent like mineral spirits or a dedicated tool cleaner. If the loppers are heavily rusted, steel wool or a rust eraser may be needed to prepare the metal surface. For easier access to the cutting blade, the loppers should be disassembled at the pivot point using the appropriate wrench or tool.
Step-by-Step Sharpening for Bypass Loppers
Bypass loppers, the most common type, operate with a scissor-like action where the sharpened blade passes by a non-sharpened counter-blade. The sharpening process focuses exclusively on the single beveled edge of the main cutting blade, leaving the flat back of the blade untouched. Identifying the existing bevel angle is the first step; maintaining this factory angle, often around 20 to 25 degrees, is necessary to prevent rounding the edge and ensure a precise cut.
Use a file or sharpening stone with a consistent, one-directional stroke. The file should be moved from the pivot point toward the tip of the blade, always lifting the tool on the return stroke to avoid dulling the edge. Using a coarser grit file first will quickly remove nicks and restore the edge shape, followed by a finer grit stone to polish the edge for maximum sharpness. This filing action will create a thin, raised edge of metal, known as a burr, along the back, flat side of the blade.
The burr must be removed, as leaving it in place will compromise the quality of the cut. To remove it, turn the blade over to the flat side and lay a fine-grit sharpening stone completely flat against the surface. Move the stone across the flat back of the blade a few times, using very light pressure. This gentle action shears the burr off without creating a new bevel on the flat side, which would ruin the bypass action of the tool.
Check the sharpness frequently by running a finger perpendicular to the edge to confirm the burr has been completely eliminated. The aim is to create an edge that is sharp and uniform along the entire length of the blade. For blades with a slight curve, the file must follow this contour to ensure the entire cutting surface is sharpened evenly.
Finishing the Job: Cleaning, Reassembly, and Lubrication
After the sharpening is complete, all parts of the loppers must be thoroughly cleaned again to remove any metal filings or abrasive particles. These microscopic metal fragments can cause premature wear if left within the pivot mechanism or on the blade surface. Use a clean, dry rag to wipe down both the sharpened blade and the counter-blade, ensuring all grit is removed.
The loppers can then be reassembled, paying close attention to the pivot mechanism, which controls the tension between the blades. When reassembling, the pivot bolt should be tightened until the blades move smoothly but with a slight resistance, indicating the correct operational tension. If the blades are too loose, they will create a sloppy, crushing cut; if they are too tight, they will strain the user and the tool.
The final step is to apply a suitable lubricant, such as a light machine oil, to the pivot point and the entire surface of the blades. Applying oil provides a protective barrier against moisture, preventing rust and corrosion. A thin coat of lubricant should be spread evenly and then any excess should be wiped away before the loppers are stored. Sharpening anvil loppers, which have a straight blade that cuts onto a soft metal bar, is simpler, as it only requires sharpening the single bevel on the cutting blade, but the same cleaning and lubrication steps apply.