Wedges and feathers are tools designed to split rock when driven into a drilled hole or natural crack. The wedge fits in the hole between two feathers whose flat sides form a guide that prevents the wedge from jamming as it is driven into the hole. Use wedge and feathers as follows: Position the feathers in the hole so the flat sides of the wedge will be parallel to the line along which the break will occur. Drive the wedge into the slot between the feathers until the rock cracks, or until it sticks in the rock. Then tap the wedge lightly back and forth along the inside edges of the feathers until it is freed. Remove the wedge and, if necessary, begin again. Proceed slowly to allow the tools time to do their work.
To be effective, wedges and feathers must be correctly sized. The diameter of the wedge rod and feathers at the point where the rod meets the feathers must exceed the diameter of the hole. Driving the wedge between the feathers forces them against the sides of the hole and splits the rock.
Avoid unnecessary stresses on wedges and feathers by drilling holes as straight as possible. Straight holes help keep wedges and feathers from binding or jamming in the hole.