64. Binding-Post. Fig. 31. This consists of a screw, screw-eye, bur and a metal strip, ¾ × 1¼ in. The apparatus wire should be fastened under the screw-head. Any outside wires which are to be joined to the apparatus should be clamped under the bur by turning the screw-eye. A small hole should be made in the wood before putting in the screw-eye. (See [App. 25].) Do not turn the screw-eye too hard, or you will spoil the thread made in the wood.
| Fig. 30. | Fig. 31. | Fig. 32. |
65. Binding-Post. Fig. 32. The size of the bolt used in this form of binding-post will depend somewhat upon the thickness of the base of the apparatus. In general, a ¾ or ⅞ in. base should be used where screws or screw-eyes are necessary. With this kind (Fig. 32) a thin base can be used. The head is shown counter-sunk into the bottom of the base. This is not necessary, provided at least 3 heads are placed far enough apart to form legs for the apparatus to stand on. Strips of wood may be nailed upon the underside of the base to make room for the heads in case they are not used as legs. The wires should be pinched between the nut and the copper bur shown. If the bolt is too large for a bur, an iron washer may be used. A washer may be made of tin, or two nuts may be used.
Fig. 33.
66. Binding-Post. Fig. 33. This is a suggestion for a combination of [App. 44] and [47]. It is useful in school apparatus. Wires may be permanently fastened on the right, under the nut, and a spring, as in [App. 44], may be slipped on the metal strip at the left, which is held under the head of the bolt.