To facilitate the insertion and extraction of the dies in and from their places in the stock, the Morse Twist Drill Co. employ the following construction. In [Figs. 294] and [295] the pieces a, a′ which hold the dies are pivoted in the stock at b, so as to swing outward as in [Fig. 295], and receive the dies which are slotted to fit them. These pieces are then swung into position in the stock. The lower die is provided with a hole to fit the pin c, hence when that die is placed home c acts as a detaining piece locking the pieces a, a′ through the medium of the bottom die.
Fig. 296
In other dies of this class the two side pieces or levers which hold the dies are pivoted at the corner of the angle, as in [Fig. 296]. In the bottom of the stock is a sliding piece beveled at its top and meeting the bottom face of the levers; hence, by pressing this piece inwards the side pieces recede into a slot provided in the stock, and leave the opening free for the dies to pass into their places, when the pin is released and a spring brings the side pieces back. Now, since the bottom die rests upon the bottom angle of the side pieces the pressure of the set screw closes the side pieces to the dies holding them firmly.
Fig. 297.
