In Fig. 103 is shown a common type of screwdriver. The end if shaped as shown will be found less likely to "jump out" of the groove in the head of the screw, resulting in a marred surface on the wood.

Fig. 103. Screwdriver.

Fig. 103. Screwdriver.

Screws used in woodwork are of two kinds: roundhead and flat-head, either bright or blued steel, or brass. They are made entirely by machines and are put up in pasteboard boxes and sold by the gross. The size of a screw is designated by its screw gage and its length in inches. Fig. 104 shows the manner of placing a screw in the screw gage to determine its gage. Fig. 105 shows the manner of determining its length. When fastening two pieces of hardwood together, holes will have to be bored in both lower and upper piece as shown in Fig. 106. This illustration shows the screw hole in the upper member countersunk ready to receive a flat-head screw. Round-head screws require no countersinking. Upon soft wood the hole in the lower member is not necessary.

Fig. 104 Screw Gage in Use

Fig. 104 Screw Gage in Use.

Fig. 105 Determining Length of Screw

Fig. 105 Determining Length of Screw.

Fig. 106. Holes Bored in Hard Wood for Screw

Fig. 106. Holes Bored in Hard Wood for Screw.