Ans. The straight out coil may be wound on a former such as shown in [fig. 384]. This consists of a board having four upright pins, A, B, D, E, properly spaced and two horizontal pins C, F, attached to extensions at each end of the board. A coil of the required number of turns is wound around these pins and then opened out as in [fig. 385]. After varnishing and baking it is ready to be placed on the armature.
Ques. For what class of winding are straight out former coils suitable?
Ans. For barrel winding.
Fig. 384.—Method of winding "straight out" coils. There are several ways of making these coils. A former may be prepared, as shown in the figure, with a board having inserted four pins, and having attached two blocks at the ends carrying horizontal pins as shown. Around the several pins, the coil is wound to the required number of turns and taped. This coil differs from the evolute coil in that the two halves are of equal size, the parts which act respectively as upper and under inductor being of equal length. The coil as shown is suitable for wave winding.
Fig. 385.—Appearance of straight out coil after being opened out. In opening out the coil, the ends C and F are put into a clamp and twisted at right angles to the plane of the coil. The letters correspond to the points indicated in [fig. 384].
Ques. How are straight out coils placed on the core?
Ans. In the same manner as described for evolute coils; when in position straight out coils appear as in [fig. 372].
Ques. What is the approved method of putting tape on a coil?