The bit-brace, which is used to hold the auger bits, screw driver bits, countersinks, etc., consists of a chuck Fig. 136, a knob, and a handle, or sweep. The chuck is made to grasp the square shank of the bit by revolving the sleeve which forces the jaws against the bit. Some bit-braces are quite expensive, yet the more simple styles are the best for ordinary work. The ratchet brace shown in Fig. 137 is convenient for use in places where the sweep cannot make an entire revolution, and for boring in hard wood and for turning large screws.

Fig. 137. Ratchet Bit Brace.

To insert the bit, grasp the sleeve firmly with one hand and revolve the brace by grasping the sweep handle with the other hand. Revolve the brace until the shank of the bit will pass between the jaws, allowing the ends of the jaws to grasp the round part of the bit shank, the square portion passing into the chuck out of sight. After the bit has been placed as far into the jaws of the chuck as it will go, revolve the sweep in the opposite direction until the bit is held firmly.

Fig. 136. Plain Bit Brace.