A little pictorial story on building the boiler...

The cracking was due to "Intergranular penetration of silver solder due to cold working and thermal expansion stresses".

This could have been avoided had I known about this single non-desirable property of the copper-nickel material.

It NEEDS TO BE ANNEALED, not only before, but also AFTER it is cold worked - such as bending out the sides of the firebox.

50 hours of work down the drain. The 2-6-0 project is in a state of hiatus at the moment, while I'm contemplating how to continue... :-(

For a thorough description of the boiler and of the reasons for the disaster, please see the extensive article in "Live Steam & Outdoor Railroading" magazine, May-August issues 2006.

Here's a good source of info, a 52-page tutorial on joining nickel alloys: