Fig. 80.
In using the screwdriver bit, especially in driving screws into hard wood, the bit will tend to jump out of the groove in the head of the screw. To avoid its jumping entirely out and marring the wood, take but half a revolution at a time, then move the brace backward slightly before proceeding again. This allows the bit which has partly worked its way out of the groove to drop back again.
The manner in which a screwdriver bit is sharpened has much to do with its working properly. It should be sharpened like the screwdriver.
42. The Brad-awl.
—The brad-awl is used for boring very small holes. Unlike most boring tools it does not remove the material from the opening it makes.
Fig. 81.
The cutting edge of the brad awl should be placed across the grain in starting, and the tool turned half way around and back again, repeating until the proper depth has been bored. It is withdrawn with similar turnings. [Fig. 81].
Patent spiral screwdrivers and automatic drills have come into quite common use in recent years. They are used mainly upon light work; their advantage being the rapidity with which they do their work.