advisable to first rough down each of the ends of these pieces to within about 1/64 inch of finished size. Then carefully set the tool in the tool holder and make a finishing cut across the piece.

Now, without backing the tool away from the work, run the tool along toward the back center of the lathe until it has passed the end of the piece. Turn your work around in the lathe and make a finishing cut along the rod until that end is sized down as far as the collar. The other rod can then be mounted and finished likewise.

This is an excellent method to use where two or more pieces require to be finished to the same diameter. It only requires one setting of the tool and the result is more certain to be accurate than where each piece is separately calipered and turned down singly.

The side of the collar which rests against the field punchings must be carefully squared up, and the corners cut out with a side tool, as the collar must bear squarely against the punchings in order to keep the machine in perfect alignment.

After the rods have been sized down to fit the holes in the field punchings their ends must be turned down to a diameter of inch for the length shown on the detail drawing.

If, however, these rods are turned in an engine lathe the threading of the rods for the 3-inch nuts, which are used to clamp up the field punchings, should be cut first as the rods will be stiffer then than after the ends are cut down.

In machining these parts it is of the utmost importance that the distances between shoulders on both these rods should be exactly the same. If this is not the case, when

the bearings are placed on the ends of these rods and the 1-inch nuts screwed up, the inequality of the distances will draw the parts out of shape to such an extent that the shaft holes in the bearings will not be in line and the shaft cannot be revolved.

As before stated, it is best to cut all threads in an en

we are to do all the work on a foot lathe the threads must be cut with a die.

An excellent way of starting the threads is shown in Fig. 6.

In this case the rod is held in the chuck and the die

holder placed against the tail stock, after the back center has been removed.

One end of the die-holder rests against the lathe bed. The tail stock should be loosened so that it can slide on the lathe bed. If the tail stock of the lathe is then firmly pressed against the back of the die-holder, with one hand, and the lathe head revolved forward by pulling the belt with the other hand the die will start squarely and the thread will run straight. Of course, the die should be opened so that this cut over the work will be as light as possible. The die can be closed down to size and again run over the work when the result will be a finished thread.

The 3-inch thread will probably have to be cut by hand, champing the work in the jaws of the vise for that purpose, and running the die down the proper distance.. When these rods are threaded they are ready for use in assembling the field punchings.

FIELD PUNCHINGS

One peculiarity which will be noticed in these punchings is the fact that one-half of them have short yoke pieces and the other half have long yoke pieces. This, however, will be found of immense advantage when the stage of winding the field is reached.

The best way to build up the field is to take a piece of board and bore two 3-inch holes in it 1 inches apart. Into these two holes set the two side-bearing rods until the collars thereon rest against the board.

Place a field punching with a long yoke piece on one of the side-bearing rods and a punching with a short yoke piece on the other rod. Next place a punching with a short yoke piece in position on top of the punching with the long yoke piece and a punching with a long yoke piece on top of the first punching with the short yoke piece. In this manner the entire field is to be built up with long and short yoke pieces alternating in each half of the field.

When several layers of punchings have been built up the 1-inch field magnet key can be placed through the holes in the ends of the long yoke pieces which will hold the two halves of the field together. The field parts will then have the appearance shown in Fig. 8.

Continue the building-up of the field punchings until the pile is just 2 inches high, at which time the 3-inch

nuts should be screwed onto the side-bearing rods and the punchings thereby clamped up firmly together.

If any of the punchings are found to have a "burr" on one side, caused by the operation of punching, it

FIG. 7.-Field Punchings Showing Short and Long Yoke Pieces.

should be removed carefully with a file in order that the punchings may fit together close and not cause an unevenness in them.

After the punchings are all in place the field magnet