Drill Jigs Principles of Design Machinery ... - Evenfall Studios

8 No. 3 DRILL JIGS
more holes are drilled, and before all are drilled, it would cause a
variation that would in all probability spoil the piece of work. When
but a few pieces are to be drilled with a jig it is not generally con-
sidered advisable to make jigs with fastening devices, the wor^ being
held in place with a clamp, as shown in Fig. 7. In order to do away
with any possibility of change of location, a pin is forced through
the jig hole and the hole in the work after drilling the first hole. If
many holes are to be drilled in a piece it is advisable to have two
pins. After drilling a hole in one end of the piece, force in a pin;
then drill a hole in the opposite end, and place a pin in this hole, as
shown in Fig. 8. The pins in opposite ends of the piece will prevent
ijs slipping when the rest of the holes are drilled. Many different
forms of fastening devices are provided, the design depending on the
class of work. One of the most positive methods consists of a screw
which passes through a stud or some elevation on the jig, and presses
C
Fig. 7
c