While the form of jig shown in Fig. 256 would give satisfaction on certain classes of work, the process of putting the work into the jig and taking it out would be very slow, as it would be necessary to clamp the work securely to resist the pressure of the cutting tools. In order that work may be handled rapidly during these operations, jigs are designed so that the work will rest on the base of the jig as shown in Fig. 283. A leaf or cover containing the bushings can be raised when putting the work in place and taking it out.
Fig. 285. Jig for Drilling Holes from Both Sides.
When the pieces to be drilled are of a uniform thickness, the leaf may be made to rest on the piece; but should they vary in thickness, the leaf would not be parallel to the base, and, consequently, the hole in the bushing would not be at right angles to the piece to be drilled. For this reason a little space is left between the top of the piece to be drilled and the bottom of the leaf, as shown in Fig. 284; a steady pin having a shoulder is located at the handle end of the jig. The upper end of the pin may project into a hole in the leaf, as shown, thus relieving any strain on the joint of the jig occasioned by the action of the cutting tools.
Fig. 286. Jig with Legs on Both Sides.