Backlapping

The sharpening of the bottom blade of a cylinder mower, to maintain blade and cylinder edge sharpness. Loosen the cylinder so it will revolve easily, but slightly touch the bottom blade. Apply grinding paste, typically with a paint brush, along the entire length of the blade cutting edge and along the cylinder itself. Reversing the direction of the cylinder so there is a slight grinding noise as the paste produces a sharp edge to the bottom blade in particular. Adjust the oncut so there is always a rasping noise indicating that the paste is doing its job. Once a sharp edge has been produced on the bottom blade then make sure all the paste is wiped off the cylinder and blade, otherwise when the mower is set to normal operation it will quickly blunt any sharpness just produced.