When electric hair trimmers become dull, they clatter and tend to yank hair out by the roots instead of cutting. This annoying process can be avoided by periodically sending your blades to a commercial sharpening service that specialises in clipper blades. However, some sharpening services are expensive. Learning how to hone your own clipper blades is a worthwhile skill to acquire.
Undo the two blade-retaining screws from the underside of the Wahl hair trimmer with a small Phillips-head screwdriver. Remove both blades.
Soak the blades in denatured alcohol for a minute. Scrub them clean with an old toothbrush.
Place the moving blade on a fine-grit oil stone with the serrated cutting edge and the two square contact lugs flat on the stone. Add a few drops of sewing machine oil to the stone.
Lower the clipper onto the blade and engage the oscillating clipper lugs. Switch the clipper on.
Apply moderate downward pressure and move the Wahl hair clipper back and forth along the length of the stone while keeping the blade in full contact with the surface of the stone. You will hear the blade grinding against the stone. Continue for one to two minutes.
Turn off the clipper. Wipe the oil off the blade with a lint-free rag. The flat serrated cutting surface and the two square lugs opposite should be shiny.
Remove the guide from the fixed blade by unscrewing the two retaining screws with a small flathead screwdriver.
Place the fixed guide blade flat on the stone with the cutting surface down. Add another few drops of oil onto the stone.
Hone the blade by rubbing it straight up and down the stone for one minute with moderate downward pressure. Continue for another minute while adding small circular movements to the guide blade.
Clean both blades and the guide with an old toothbrush and some denatured alcohol. Apply a thin film of oil to the blades. Reassemble the clippers. Adjust the guide blade by aligning the tines 1/16 inch from the end of the moving blade. Tighten the two retaining screws and test the clippers.
Dress the oil stone before sharpening by rubbing it lengthwise up and down the matching surface of a coarse stone. Clean the trimmer blades and apply a single drop of sewing machine oil to the blades before each use.