Fig. 46. Section Form.
About ten pounds of No. 34 B. S. gauge silk covered wire are required to wind the sections. Cotton covered wire must not be used to avoid expense, because with it a sufficient number of secondary turns cannot be secured to bring the secondary current up to the proper voltage. By observing explicitly the instructions and precautions given below no trouble will be experienced in handling enameled wire and forming the sections. The form should be placed in a lathe chuck or some other machine which is convenient and whereby the form may be rapidly revolved under the control of the operator.
Saw slots are cut in the wooden flanges and the center of the form as shown in the illustration so that silk threads may be passed under and around the completed section and tied so that a possible "cave in" of the wire is prevented. After tying up the section should be removed from the form by unscrewing the nut and taking off the flange.
Fig. 47. Methods of Connecting Sections.
When winding the wire it must be very carefully watched for loops or kinks and only be laid on in even layers. It must also be borne in mind that enameled wire cannot be as tightly wound as fiber covered wire for reasons heretofore explained. In case the wire becomes broken, it must be smoothly spliced and soldered. Do not under any consideration use acid as a flux or heat the wire with a flame. Acid will corrode the fine wire, and the flame will badly oxidize or melt it. Use a short piece of No. 8 B. S. gauge tinned copper wire set in a small file handle as a soldering iron, and rosin as a flux. Paraffin some silk binding tape such as dressmakers use and wrap the joint with a small piece. The sections as they are removed from the winder must be taped and then carefully marked with an arrow which points in the direction of the winding.
Fig. 47 illustrates the two methods of connecting up the sections. It will be noticed in the second method that the arrow denoting the direction of winding points down on every alternate section. This does not indicate necessarily that every alternate section is wound in an opposite direction from the other, but that they have merely been turned around so that the arrows come on a reverse side of the core and point in an opposite direction. This precaution must be taken in order that the current will flow through all the sections, and is made necessary because the inside terminal of one section is connected to the inside terminal of the adjacent section and the outside terminal of that section is connected to the outside terminal of the next adjacent section. The first method, A, illustrated in Fig. 44, is less complicated and does not require this reversal, but for various reasons is not to be recommended in place of B.
Eight of the completed and taped sections are placed on each "leg" of the transformer, with one of the fiber separators between each pair as in Figs. 48 and 49. When each "leg" has been completely assembled, solder all the secondary terminals together so as to connect as in Fig. 47.
Fig. 48. Assembly of Leg.