It will next be necessary to lay out the armature windings themselves in order that we may complete the details of the flanges and spider. Note now how the draftsman has made a diagram, Fig. 7, showing with single lines how the conductors are to be arranged. He has taken the first and nineteenth slots, showing the conductors as lines; he has shown the first three and the last commutator bars, to show their relation to the conductors; and finally, he has made an end view, showing the relation of the conductors in the slots.
He next draws the same set of coils to such a scale as will show all necessary detail, Figs. 1, 2, 3, and 4, putting on full and complete dimensions as obtained from the design data and the dimensions of the armature core, and as determined from the coils themselves.
A cross section of one set of conductors in one slot is next drawn, Fig. 5. This must necessarily be drawn to a very large scale, such as twice the size, in order that all dimensions may be shown without sacrificing clearness. In this section it should be noted that several diametrical dimensions are given and that the dimensions of the slot are shown along with the corresponding dimensions of the coil.
A side view of the coil assembled in the armature core is next shown, Fig. 8. This view shows a number of details which are covered completely with very little labor. For instance, the binding wires are shown and described completely, although nothing more than a section is drawn. This illustrates very well the use of good explanatory notes and their value as labor savers. This view also shows the armature flanges and determines their general dimensions, as related to the coils.
Another point in connection with this drawing which should be given attention is the method of calling for the various parts. It will be noted that a table is included in the lower right hand corner. This table gives on the right the name of each part, with a number which refers to a corresponding number in the body of the drawing. Note that these numbers on the drawing are made large and enclosed in circles, and that arrows are added where necessary to call attention to the proper part. The table contains, still farther to the left, the proper material to be used and the number of parts required. Such tables are Used by some drafting rooms and undoubtedly prevent confusion due to placing too much data on the body of the drawing.
The drawing is made primarily to show the armature coils, and to do this we have a plan, a side elevation, and a section. The plan and elevation do not bear the relation on the sheet that the laws of projection require, but nothing in clearness is sacrificed, space is saved, and the drawing is really made easier to read.
In addition to showing all necessary details of the coils, sufficient data is given from which to make the next drawing. In other words, we have determined enough of the physical dimensions of the armature flanges to know how they must be built to support properly the ends of the coils, giving necessary clearances for insulation, etc.