This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
The proper metal for spanners generally, is a soft fibrous Bessemer steel; such metal is produced by rolling and hammering the Bessemer product after being cast, that the fibrous character may be produced. If such steel is soft enough, it will weld, and spanners of all shapes may be made of it.
To make a gap spanner quickly for immediate use, one end of an iron or steel bar is heated to a bright yellow heat, and bent until a hook is formed; the work is next heated at the curved part, and lengthened or shortened until the gap is of a proper width. A gap spanner of this character is shown by Fig. 108. Another simple class of gap spanners are those made of thin bar or plate steel. A spanner of this sort needs no thinning to produce the handle, because the gap portion is no thicker than the handle; it is therefore made by cutting out with chisels while the plate is at bright red heat. Small spanners only should be made by this mode, because of their wide gap portions, and are represented by Figs. 109 and 110.
Small gap spanners, of only 1 or 2 lb. each in weight, are easily made of steel, and should have cylindrical handles, usually termed round handles, to promote an easy handling. Large spanners may have broad thin handles, that they may be light, and the two edges or narrow sides are curved. A gap spanner with only one gap end is made by providing a bar which is thick enough to be made into the spanner's gap portion without upsetting, and thinning the end of the bar until it is of the desired length and shape for the spanner's handle. The gap in the thick portion is next made by first punching a hole at the place for the bottom of the intended gap, a round punch being used if the bottom is to be curved, and a 6-sided punch or drift, if the bottom is to be angular. When the hole is made, two slits are formed from the hole to the extremities, and the superfluous gap-piece is cut out, at which time the work is roughly prepared for an after trimming. Another spanner is next partly made by the same means of the same bar, if necessary, and any greater number that may be required.
A spanner in process of being made of such a piece is indicated by Fig. 111.
The forging of a spanner which is to have a gap at each end is effected by making two gap-pieces, each one having a gap of proper size, and an end or stem of about half the entire length of the intended spanner. These two stems are scarfed, or a tongue-joint is made, for the purpose of welding them together, which produces the desired spanner having a gap at each end. After being shaped at the gap parts, the spanner is bent, whether it has one gap or two, the bending being necessary that the spanner may be applied to the 6 sides of a nut by moving the handle to and fro in the shortest possible space. This bending consists in heating the junction of the gap part with its stem, and bending it until the handle or stem is at an angle of 15° with the gap-sides.
The final shaping of a gap-spanner consists in trimming the edges with a trimming chisel and curving the outer surfaces. Half-round top and bottom tools are employed for this curving, and the edges of the gap portions are shaped while between such tools, and also while a filler is in the spanner's gap. This filler is of steel, and is long enough to be supported on a couple of blocks, or across an opening of some sort, while the spanner's gap-part is held on the filler and shaped with the top and bottom tools. One narrow side of the filler is angular, similar to the bottom of the gap, and the thickness is the forged width of the gap; consequently, while the outer surfaces are being shaped at the time the filler is in the gap, both the gap and the outer edges of the gap portion are shaped at one hammering.
In order to provide good bearings in the gap surfaces, and to prevent the entire gap portion being too broad, and thereby occupying too much room, the thickness of a gap portion belonging to a small spanner should be about equal to the height of the nut which is to be rotated, and the total breadth across the gap part only about 3 times the diameter of the hole in the nut. Large spanners for nuts 3 or 4 in. height, may have gap parts which are two-thirds of the nuts' heights. The proper shape for the bottom of a spanner's gap is angular, that it may fit any two contiguous sides of a 6-sided nut or bolt head. Gaps of such a form will suit hexagonal nuts and square ones. A gap with a curved bottom bruises the nuts' corners, and it must be made very deep to prevent the spanner slipping off while in use. By Fig. 112 a spanner is represented whose gap part is of proper shape.
Gap spanners are often forged of ordinary fibrous wrought iron, and after they are properly finished and the gap surfaces smoothly filed to suit the nuts, the entire gap portion of each spanner is hardened; this is performed by heating it to a bright red, rolling it in powdered prussiate of potash, and then cooling it in clean water. Small iron spanners, that are only 6 or 8 in. long, are put into a box with bones or hoofs, and their entire surfaces are steeled, similar to the mode for steeling other small tools.
Cast-iron spanners are those that are made by pouring the metal into sand moulds that are shaped with wood or iron patterns resembling the spanners to be cast. After casting, the spanners are softened by a long gradual cooling, which makes the metal soft, and prevents the tool breaking while in use, although the metal is not made fibrous. Cast steel thus used is a preferable metal to cast iron.
The stems and handles of socket spanners are made of round iron or steel, and separate from the socket portions. The socket portion of the spanner consists of a tubular piece which is attached to the stem by welding its end in the socket hole. This socket piece may be an end of a thick tube, if such a piece can be obtained with a hole of proper diameter. The socket may be made also by punching a hole through a solid piece, and drifting the hole to a proper shape and size; this produces a good socket if the metal is solid. The convenient mode of making a socket of an iron or soft steel bar consists in curving to a circular form one end of a bar which is about as thick as the intended socket, and welding the two ends together by means of a sort of scarf joint termed a lap joint. Such a joint is made by tapering both the ends that are to be welded together, and curving the socket piece until its hole is about three-quarters of its finished diameter, which allows the socket to be stretched with welding to its proper diameter. After a socket is made by either of these means, its hole is shaped with a steel 6-sided drift which is of the same shape and thickness as the required socket hole.
One end of the socket is next heated and upset, to make it thicker and larger in diameter than the remainder, at which time it appears as in Fig. 113, being then ready for welding to the stem.