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#10347
BRIAN MARSHALL
Participant

Hi,
I have had very mixed results from attempts at welding Scott crankcases over the years, from both my amateur attempts, and from top-notch professional alloy welders, and I’ve come to the conclusion that the factory changed alloy casting suppliers from time to time, and that the quality of the metal varied accordingly. Whilst the straight-back crankcases of 1927/8 are usually quite good, there are some around that have a markedly darker colour to them, and they are almost impossible to get a good polish on, and tricky to weld. The late 1928 and 1929 RZ and RY crankcases are VERY brittle, prone to cracking, and difficult to weld. Once they have cracks around the main bearing cup housings they are usually beyond redemption. Things then seem to have gradually improved through the 1930’s, but there were some bad crankcases immediately after the war, when there was a huge glut of scrap aluminium around from the scrapping of thousands of aircraft. Instead of ‘virgin’ metal, it would be an unpredictable brew of duralumin, aluminium, and maybe some magnesium or zinc thrown in for good measure.
When metal is relatively porous it becomes oil-saturated, and that of course prevents good welds being achieved. In conclusion, it is all really a matter of ‘pot luck’, melting pot luck !
Brian