Material. Flat mild steel as available; for practice, material about 30 x 12 mm is the easiest to handle; two pieces about 150 mm long may be used.
Additional tools. Half-round hot chisel of 6-mm radius; if a helper is available, a flatter and a 12-mm top fuller, hot set or chisel.
Where sharp angles in flat material are required, it is often quicker and easier to make a corner weld rather than to make the corner from one length. Although the job described and illustrated is a right-angle corner, other angles can be produced in a similar manner. Both pieces are upset (Fig. 37A). The amount of upsetting depends to a large extent upon the skill of the smith but, as an example, 12-mm bar would be upset to about 14 mm in thickness. Pieces are then heated and cut with a sharp hot set or hot chisel (Fig .37C and 38). In this case the cuts are at an angle of 45 degrees to the centre line of the metal.
Cut the angles from one side, thus leaving bevelled ends that facilitate the scarfing. Scarfing can be carried out as in Fig .39 or by using a fuller instead of the edge of the anvil. Now decide the best position on the anvil for the initial welding and mark a right angle with chalk. This will be a guide for placing the pieces correctly. Bring both pieces to a full-welding heat, position (Fig .40) and apply quick, light hammer blows to weld the joint. If the position shown in Fig .40 suits the smith, this is where the chalk marks should be made.
Hammer blows must be applied quickly to both sides, working from the centre outwards to expel slag and to ensure that the scarfs are properly welded. One heat should be sufficient but a second may be necessary. Flatten the metal to its original thickness and true up the angle, checking with a square and working surplus material toward the inside of the corner. Trim off surplus material with the half-round hot chisel to leave a pronounced radius inside the corner. If work is needed on the outside of the angle, use the radiused edge of the anvil (Fig .41) to preserve the inside corner.
Most finishing and trueing up should be carried out as in Figs 42,43,44 and 45. Try to avoid working over the edge of the anvil.
When adjusting the angle, remember that stretching the inside of the comer will open the angle, while hammer blows on the outside comers (Fig. 45) will
close it up. Figures 42 and 43 illustrate a comer being squared up while at the same time surplus metal is being worked into the workpiece to leave clean square edges on the outside. Stretching the inside of the comer is shown in Fig. 44.
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