Rob Roy Boiler

[Barney66]

3.5" Rob Roy boiler; in what order and with which melting point solder is it best to deal with the throatplate and the wrapper extensions etc? All in one hit, or do the wrapper extensions first with the reinforcing strips, all loosely rivetted to the barrel, then the throatplate? I have 455 and 438 silver solder, and would like to use the 438 for it's higher melting point for this, then the 455 for the foundation ring etc. I have a Seivert propane setup. Similarly I would use the 438 for the firebox wrapper/tubeplate and lower melting point 455 for the tubes.

[millman]

I would do both joints together, cannot help with 455 and 438, I am still using up stocks of easyflo, C4 and B6 but it sounds like a good idea to use a higher melting point alloy for those joints.

[springcrocus]

When Wilf and I were making the Britannia boiler, there were a couple of instances where we used 38% silver solder rather than 55% and it needed a much higher level of heat that we expected. For a single torch, you might start to doubt yourself before you get the workpiece hot enough! Following our experience with 38% silver-solder, we finished the whole of the rest of the boiler with 55% solder and never once had an instance of remelting existing joints. Unless you are confident that you can get the heat in for the 38% stuff, just build the whole thing with 55% and sell the 38% to someone else.

Regards, Steve

[runner42]

The Rob Roy boiler is fairly small so using a 1" dia propane torch should be able to be used on the extension to the wrapper with 55% silver solder and similarly on the throat plate. You shouldn't experience any re-melting of adjascent joints so using different melting point silver solders is uneccessary. Doing them individually or together is just a a matter of choice, but if you feel that an individual approach is preferred then do the wrapper extension first because it is rivetted and this mechanical connection would prevent movement in the unlikely event that you re-melted the solder when doing the throat plate. Later assembly work you may struggle with that size of propane torch and a bigger one or oxy-propane be required.

Brian