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13. Forging a hinge pin for use on a wooden gatepost

Material. Mild-steel square section of 16 mm and 85 mm long; mild-steel round section of 12 mm and 65 mm long.

Additional tools. 12-mm bottom swage; 25-mm bottom swage; bolster plate with 12-mm hole; punch; hot set.


Upset one end of the 16-mm square section in the 25-mm bottom swage until the end is 25 mm wide and just over 16 mm thick (Fig. 95A). Heat to a bright red heat and in this end punch a hole fractionally smaller than 16 mm in diameter (Fig. 95B). Chamfer one end of the 12-mm round section and upset the other end to about 18 mm in diameter to give a mushroom shape (Fig. 95C). 

Heat the punched end of the square section to a bright red heat and drive the upset peg into the hole, settling it firmly into position. Place the bolster plate over the tool hole of the anvil having made sure that the 12-mm round peg will pass easily through the hole.

Take a full welding heat on the upset parts with the peg uppermost in the fire. Heat slowly to give time for the whole thickness of the job to reach welding temperature. At full welding heat remove the job from the fire, quickly pass the peg through the hole in the bolster plate and hammer the upset end of the peg to complete the weld (Fig. 96). After the initial blows a set hammer can be used to flatten the end neatly. Do any straightening needed and make sure that the peg is at right angles to the shank of the job. The width of the point should be the same as that of the metal, i.e. 16 mm. Next, take a bright red heat over this pointed end over a length of about 60 mm and lightly drive a hot set into the edges (Fig. 97). This gives a ragged finish that will firmly fix the hinge peg into a wooden post. Only five or six cuts on each edge are necessary. Finally, true up the work, wire-brush it and allow it to cool.

Select tongs that fit well on the peg or hinge pin. Take a near-welding heat on the unwelded end of the job and forge a flat point (Fig. 95E). Note that one side is flat.

Agricultural engineering in development

Figure 95

Agricultural engineering in development

Figure 96

Agricultural engineering in development

Figure 97

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