Material. Flat, square- and round-section mild steel as available.
Additional tools. Hot sets and hot chisel sharpened from one side only; side set; set hammer; top and bottom swages; a hole gauge; if desired, a monkey tool may be made but it is not essential.
The blacksmith must often forge shoulders in the form of tenons, pegs and rivet ends for many applications. Some examples shown in Fig. 95 are: flat-to-round (A); square-to-round (B); round-to-square (C); square-to-square with upset shoulder (D).
Among the tools used for these operations are a side set (Fig. 96) and a monkey tool (Fig. 97). The side set is similar to a rather short, blunt hot set with one vertical face and another face at about 45 degrees to it with a small radius on the edge like a thin fuller. The monkey is essentially a block with two holes at right angles to each other and is used (Fig. 98) to finish and true up shoulders where the use of a bolster plate would present difficulties. One hole is the correct size for the peg end to be forged while the other provides clearance for the end of the peg end.
If used, monkeys are required in a number of sizes and the holes need to be drilled with the peg hole slightly countersunk where it will meet the shoulder.
To produce the type of peg end shown in Fig. 95 A, the easiest method is to cut away the unwanted material, leaving a square shoulder, and then forge the peg. Some smiths prefer to use a hacksaw to cut away the surplus material. This takes more time but leaves neat and clean surfaces.
A good job can also be done by using a hot set or hot chisel sharpened from one side only and with a slightly blunted or radiused cutting edge like a very thin fuller. Carefully mark out the positions of the shoulders and, from the centre line, the width of the peg and then centre-punch these marks. Heat to a bright red heat and cut the shoulders from both sides nearly to the full depth (Fig. 99). Reheat if necessary and cut along the sides of the peg (Fig. 100), removing metal from both sides and leaving the centre part. This centre section is then forged to a square section (Fig. 101). A set hammer may be used close to the shoulder. Next, remove the corners (Fig. 102) to give an octagonal section. Finally, round up to size in top and bottom swages (Fig. 103) and check the size in a hole gauge (Fig. 104). Any surplus length is then cut off with a hot set or hot chisel, working all around the peg to give a neat finish.
To form the square-to-round peg (Fig. 95B), the shoulder positions are marked with centre-punch marks. At a bright red heat, a side set is used to set in the shoulders (Fig. 105). Work around the four sides of the bar, entering the side set a little on each side until just short of the full depth (about 1 to 2 mm short but it will depend on the size of the workpiece). Reheating as needed, forge to a square section using a set hammer with slightly radiused edges. With hand hammer or set hammer remove the corners and finish between top and bottom swages.
Great care is needed to keep these peg ends on centre throughout the forging operations as very little, if any, correction can be made later.
The round-to-square tenon (Fig. 95C) is made in much the same way as that shown in Fig. 95B.
Additional care must be taken to keep the side set vertical and at right angles to the centre line of the metal. Set in as for the previous workpiece, then forge to a square section with hand or set hammer. When working with the round section, it is more difficult to turn the work exactly one-quarter of a revolution when setting in the shoulders. If necessary, each of these workpieces can be trued up in a bolster plate or with a monkey tool. Slight errors in the squareness of shoulders or some unevenness can be corrected. Tenons and pegs must easily fit into these tools and smoothly pass through up to the shoulders.
The square-to-square tenon with reinforced shoulders (Fig. 95D) is made by upsetting in the shoulder position and then working with side set and set hammer as before. Again, trueing up and finishing are done in a bolster plate. This type of tenon will be encountered later when making spike-harrow tines. Some smiths prefer to draw-down the ends of pegs and tenons a little and then use a set hammer and the edge of the anvil or the edge of a suitable block held in the tool hole of the anvil. Try both methods and adopt the one you prefer (Figs 107 and 108).