Screws driven into the end grain of ply-wood should be long enough to take a 3/4-inch bite into the wood. Longer screws will not add materially to the strength of the joint and may split the wood.
Screws driven into core stock or solid wood should take a 1-inch bite—but to prevent splitting, a pilot hole, half the diameter of the screw, should be drilled first in the solid wood.
Screws driven into exposed surfaces of the project should be concealed with long-grain wood plugs as shown in the photos. These plugs are cut as needed from the sides of scrap wood with a special 1/2-inch plug cutter. They differ from dowels in that their ends have the grain pattern running across the surface, while dowels have an end grain.
The advantages of long-grain plugs are many. They can be cut from wood that matches in color and grain pattern the surface being plugged, and when properly matched and fitted they be-come almost invisible in the finished piece. Plugs take stain finishes in the same shade as the surrounding wood, while dowels, with their end grains, soak up the stain and appear considerably darker than the surrounding wood.
Dowels used as plugs may in time distort due to their failure to shrink and expand in the same direction as the wood which holds them. Plugs, however, will expand and contract in the same way as the wood. Finally, if for any reason a plug must be removed later, it can be chipped out easily with a 1/4-inch chisel, while the only way a dowel can be removed is to drill it out.
