Allchin Crown Stay

[Peter Howell 1Participant @peterhowell1]

Is there a trick for aligning the crown stays with the boiler outer shell top? I have Farmer’s book but the boiler he is making has a flat top, the Allchin’s is round. They need to conform to the shape as silver solder is not a very good gap filler.

[noel shelleyParticipant @noelshelley55608]

Having looked at the book and drawings very careful fitting seems the only answer. Their main purpose is to stay the crown sheet, this is the joint that matters. The joint to the outer wrapper is less important due to it’s shape. Using a silver solder with a better gap filling property ? CuP alloys, the solder people may have advice. Brazing seems to have fell out of favour now in part because of the fear of zinc loss but since this joint is in the steam space unlikely to be a problem.

If you are a member of a club speak to the boiler inspector or other members in the know.  Good Luck. Noel.

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