Fig. 1797.
In [Fig. 1797] is represented a drilling device in position for drilling a hole from the inside of a steam boiler. a represents a base piece made with a journal stud b. This base piece is provided with radial arms a, with threaded ends and nuts made with conical projecting ends, as shown at a2. One of these pieces is used at each end of the machine when convenient, their use for centring and holding the frame being apparent. When not convenient to use two of them, one end of the frame is sustained as shown in the engraving, or in some other manner that may suggest itself. The casting b is made in two pieces, and is provided with a bearing for the pin b, and holds the ends of the rods c c. The actuating shaft g carries the bevel-wheel g, more clearly seen in the figure at side, which drives the drill spindle, whose ends are of different lengths, for convenience in reaching to different distances. The cross-head e may be slid along as required on the rods, and the revolving frame and drill turned around to different positions.
Fig. 1798.
[Fig. 1798] represents a small hand drilling machine to be fastened to a work bench. A suitable frame affords journal bearing to the upright spindle, upon which is a bevel-gear g, which is driven by a gear upon the same shaft as the wheel w. The spindle is threaded at s and is fed by the hand wheel f, which is threaded upon the screw s and has journal bearing in the cap c.
Fig. 1799.