Part 9 (1/2)

[Ill.u.s.tration: Fig. 68.]

[Ill.u.s.tration: Fig. 69.]

APPARATUS 92.

_128. Crank for Winders, etc._ Fig. 69. This form of crank or handle will be found easier to make than the one in which a wire is expanded in the slot of a stove bolt, and it can be used for many purposes, especially where dowels serve as axles. Wrap a little paper around the end of the 1/4 in. dowel, D, and push it part way into the spool, A, then put in a set-screw, S, to keep A from twisting upon D. The straight end of the wire, H, should be put into a hole, B, and another set-screw used to fasten it into the spool.

APPARATUS 93.

_129. Winder._ Fig. 70. For winding bolt magnets, this form of winder is very useful. It consists of a ”stove bolt,” S B, 2 in. long (total length) and 5/16 in. in diameter.

[Ill.u.s.tration: Fig. 70.]

130. Handle or Crank, H, is made of a stout wire, 4 in. long, bent at the lower end as shown. H is fastened into the slot of S B. To do this the end of H is hammered flat until it will just slip into the slot. It may be soldered there, or be made to fit by expanding it so that it will press out against the sides of the slot. To do this, place S B into a hole in an anvil, or hold it in a vise, being careful not to injure the thread. Place the flattened end of H in the slot, and strike it on top so that it will expand and be pinched in the slot; but do not pound it so hard that you split the bolt head. Three or four good center-punch dents upon the wire over the slot will help to expand it.

131. The Framework is made of wood, the dimensions being shown in Fig.

70. A 5/16 hole should be made for S B, the thread of which will stick through about 1/4 in. so that the winder-nut, W N, can be turned onto it. W N should be on but 2 or 3 threads of S B. This will leave part of it for the thread of the bolt magnet, and when this and S B meet in center of W N they will bind against each other and hold the bolt tight.

The winder can be nailed or screwed at S to the edge of a table or held in a vise.

APPARATUS 94.

[Ill.u.s.tration: Fig. 71.]

_132. Winder._ Fig. 71. This shows a winder that can be used for several purposes by arranging different attachments. It will be first described as shown in Fig. 71, where it is being used to wind a bolt magnet. The princ.i.p.al dimensions are shown in the figure. It is made of 3/4 in. wood about 3 in. wide, the two outer parts X and Z being nailed to the center one, Y, which is to be held in a vise, or fastened to the edge of a table. A 5/16 in. hole should be made through the upper part X and Z at one side of the center, so that a long 5/16 bolt can be put through and used as described in App. 93, if desired. A smaller hole, 1/4 in., should be made on the other side of the center for a 1/4 in. dowel. The dowel, D, is shown, and this size is a little smaller than the hole in ordinary spools, shown at A and B. One-quarter in. dowels can be made to fit fairly tight into the holes by wrapping paper around them.

Five-sixteenth bolts can be screwed into the spool holes, shown by the bolt magnet in Fig. 71. To firmly hold a spool from twisting around upon the dowel-axle, a set-screw, S S, is needed. These are small screws, say 5/8 in. long, No. 5. A small hole should be made into the spool before forcing in the screw. (App. 25.)

The spools A and B are fastened in this way, by set-screws, to D. The handle, H, is made as in App. 93, in this case a short stove bolt, S B, being used and screwed into B. Fig. 69 shows a very simple form of handle for all such purposes, which may be used instead of the one here shown. The details of winding on the wire are given under App. 88.

APPARATUS 95.

_133. Attachment for Winder._ Fig. 72. By using this addition to App. 93 or 94, almost any ordinary kind of windings can be made. The wooden block, A, may be about 2 in. square and 7/8 in. thick. A set-screw, S, binds it to the dowel-axle, D, which is made to turn by one of the forms of cranks given, and which is held in one of the frameworks. Windings like that shown in App. 112, Fig. 85, can easily be done with this, the upright part, with the two spools, being screwed right to A of Fig. 72.

[Ill.u.s.tration: Fig. 72.]

CHAPTER XI.

INDUCTION COILS AND THEIR ATTACHMENTS.

_134. Induction Coils_, or shocking coils, are rather expensive to buy, and altogether too complicated for boys to make by the methods usually given in books. The method here given is simple, the materials are cheap, and if you make them according to directions, you will have an apparatus that will, be able to make your friends dance to a rather lively tune. The amount of shock can be regulated perfectly (App. 103).

Winding. Full instructions have been given for making bolt magnets (App.

88). The winding of our induction coils is done in the same way by the same winder as the bolt magnets (App. 93), or by hand. You will find it a very tiresome and troublesome job, however, to wind on 12 or 15 hundred turns of fine wire by hand. Make a winder.

Several different forms of induction coils are shown. The coil is the most important feature, however, and we shall consider that separately.

When you understand the construction of one coil, you can readily apply this to the different forms. Some form of contact breaker, or current interrupter, is needed also. These will be treated by themselves. The connections will be discussed under each form of apparatus.