The shapes usually adopted for ends of bolts are indicated by Figs. 1094, 1095, and 1096. Bolt-ends should be formed to their respective shapes and sizes with turning-tools, previous to beginning the screw-cutting, in order that unnecessary screwing of the ends may be avoided. After the screws are entirely finished, each extremity or point should require merely a smoothing with light cuts, or with polishing, to complete it.

The bolt-end denoted by Fig. 1094 is that suitable for the greater number of all the bolts which are made, whether small or large, screwed, or without screws. It will be seen that the entire point or curved extremity in this Figure has the curve of a semicircle for its boundary. Such a form presents an elegant appearance, and also allows an abundance of metal to guard against injury to the screw.

In Fig. 1095 the end has a comparative short portion extending beyond the screw, and is suitable when but little room exists at that place while the bolt is in use. An end of this character also allows a pin-hole to be made therein, if it is specially desirable to prevent the nut's rotation after being adjusted.

Fig. 1096 shows an end having a point of comparative great length, in which a key-slot is made to admit a key. Plenty of metal also exists in such an end to prevent injury to the screw's end, and to allow a great amount of hammering without doing much damage. Such an end is therefore suitable for any bolt which is liable to become fixed tight in its hole, and which must at some time be removed without thickening the point to- any great extent, which would prevent its being driven out.

In Fig. 1099 two nuts are shown on one bolt-end. The outer nut is termed a lock-nut, because it is intended to fasten the nut next to it, and thus prevent it shifting on its bolt. The efficiency of a lock-nut depends on its amount of screwed surface, and therefore depends on its thickness or height. It is more likely to fasten its companion in proportion as it possesses greater screw-surface or friction-surface. If it is no thicker than the inner nut, it cannot fit the bolt tighter, unless the outer one has a smaller screw than the other. A lock-nut should not, in any case, be thinner than its companion, but can be as much thicker as the length of the bolt-screw will admit. A thin nut is always more liable to shift than a thick one, because of the smaller amount of screwed surface in contact with the bolt, and because of the difference between the pitch of the bolt-screw and that of the nut-screw.