Trevithick Dredger Engine- soldering the big boiler flange.

by John

Today I soldered the large flange which holds the flat end plate, to the boiler shell.  The flange is a large piece of LG2 bronze, but it is quite delicate because the centre is removed, leaving only the rim.

Here is a photo of the flange in position, fluxed, and ready to apply heat and silver.

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But before this step I made a special tool.  Can you guess its purpose?

 

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It is a disk of 12mm thick steel with a steel bar bolted to the surface.   A hint….  the disk diameter is slightly less than the internal diameter of the boiler shell.

 

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Here is the tool in use.  With all of the heat from yesterday’s brazing, the boiler shell had distorted slightly, and the flange to be soldered was a bit tight in places.  So I identified the tight spots, placed the tool against the tight spot, and gave the bar a whack with a hammer, slightly expanding the tight spots.   After this, the flange dropped into position easily and nicely.

 

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After soldering the flange.  No video I’m afraid.  Not enough hands.   To minimise the risk of the flange distorting with the soldering heat, I rested it on a plate of flat steel during the soldering.   Note the different shape of the forge for this braze.   

 

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And after the brazing, the end plate was nice and square.

 

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Square in both directions.