To hollow the underside of a ledge for covering the joint of a roof as shown in the accompanying sketch (Fig. 1), the end of the piece of wood should be marked out and a small plough groove made, as shown at Fig. 2. The greater part of the superfluous material can then be cut away with a mallet and chisel. The surfaces can be finished with a broad rebate plane or, better still, by a jack plane (or panel plane) with a side slip, which takes off as shown at Figs. 3 and i.

How To Hollow the Underside of Ridge Roll.