Material. Top section of railway-line metal, spring steel such as from a large broken cultivator tine or a piece of old motor-vehicle axle shaft; about 1 m of mild-steel rod, 8 or 10 mm in diameter.
Additional tools. Tongs adapted or made to fit across the face of the flatter; swage block; 20-mm top and bottom swages; grinder or a good second-cut file; cold chisel.
If a swage block is available, bevel a square hole to accommodate the metal section used (Fig. 152). This is easily done with a sharp cold chisel and a file. In some cases the tool hole of the anvil will be large enough, and this is bevelled.
The metal should be forged and neatly cut to about the dimensions in Fig. 151A. The dimensions of your workpiece will depend on the size of flatter required. Next, bring one end of the workpiece to a bright red or yellow heat, restrict the heat to within about 30 mm of the end by cooling, and upset (Fig. 153). Upset until, when the cool end is placed in the hole in the swage block or anvil, about 25 mm stands up above the level of the hole. Next, take a longer bright red to yellow heat and forge in the handle recesses with top and bottom fullers (Fig. 154).
Now bring the upset end to a bright red or yellow heat, place the work in to the hole and flatten it (Fig. 155). A fuller can help spread the metal in the directions required. Flatten until 8 to 10 mm of the metal stands up above the face of the anvil or swage block. Flatten as smoothly as possible with sledge- and hand hammers and use another flatter if available. The better the finish obtained, the less filing or grinding will be needed later.
With well-fitting tongs, reheat the flattened end and square up the face (Fig. 156). Again, use a flatter if available. It will probably be necessary to return the job to the swage block or anvil hole from time to time to eliminate distortion of the face. Finish up as square and flat as possible.
Next, with properly fitting tongs, reheat the opposite end of the job and forge the head end (Fig. 157) to give the shape shown in Fig. 151D. Bring the whole job to a good red heat and cool it in sand, lime or ashes to soften. When cool, grind the edges and faces flat and square. If no grinding wheel exists, this work must be carried out with a file. Next, remove all sharp corners and edges and, if the tool is for fine work such as carpenters' cutting tools and knives, the face should be polished. If you want to harden this tool, heat the face slowly to a dull red heat and quench in water by placing the other end of the tool downwards into the water first. This will give a more even rate of cooling to the face. If the face enters the water first there is a danger of cracking because the edges of the face cool more rapidly.
To temper the piece, polish the face and then place the head of the tool into the fire with the face uppermost. Observe the oxide colours and when brownish blue is reached (if you are using spring steel), requench it. During this tempering do not allow the head to reach red heat. If this happens, the head will be hardened by the second quench, damaging the hammer face, and it is likely to crack and splinter during use.
A rod handle can be fitted as described in Job 11. You must always keep in mind that a flatter is a finishing tool and is not intended for heavy forging work. Kept in good condition, it enables good finishes to be made when required. If metal other than spring steel is used, some experimenting with hardening and tempering will be needed. A good file should just be felt to be scratching the tool, but it must not file easily.