Ques. What is the advantage of this method of winding coils?
Ans. By the use of formers much time is saved, thus reducing the cost, and also by their use all the coils are symmetrical which improves the appearance of the finished winding.
Figs. 379 and 380.—Diagrams illustrating lap and wave barrel windings.
Ques. How is the required shape of the template or former for winding the coils determined?
Ans. By winding one coil on the armature in order to ascertain its dimensions and shape; it is then removed from the armature and used as a pattern in constructing the former.
Types of Former Coil.—Of the numerous shapes of former coil, mention should be made of:
1. Evolute coils;
2. Straight out coils.
Ques. Describe the evolute type of former coil.
Ans. The evolute coil is wound around eight pins inserted in a board as shown in [fig. 381]. The required number of turns are taken around these pins and their ends G and H left projecting. The coil thus formed is now covered with tape and after removal from the board, is put into a clamp at C and F, and opened up as shown in [fig. 382], which is the form required for insertion in the proper slots of the armature.