The top curved blade can be touched up with a file or angle grinder while still on the unit, or removed and sharpened on a bench grinder. (Note: The blade must be removed from the blade arm in order to sharpen on a bench grinder.) The rest on the bench grinder should be set at 15° for best results.
The shear plate (the bottom blade attached to the unit itself) should only be sharpened once for every two times the upper blade is sharpened. The shear plate must be removed from the unit and be ground at a square, 90° angle.
Care should be taken not to remove any more material than is necessary on the shear plate. Repeated, aggressive grinding results in the cutting edge dropping too far below the table surface of the Shingle Shear. For this reason, we recommend that shingles be cut with the stones up. This puts more of the wear on the top blade which can be sharpened more frequently.