As above , plus the correct sequence of 'assembly' is vital , one wrong step guarantees major problems further down the line.

Anthony,

Additional… There are some really good locomotive boiler build threads on the proboards model engineering site.

There is quite a recent 5" gauge Britannia boiler build (over the past few years) and Julians 5" gauge Terrier/Boxhill type locomotive boiler build. Both threads are excellent and show the boilers being build up from scratch including plate flanging etc.

The Britannia build also gives information on the sizes of Sievert torch and nozzle sizes, along with other silver soldering kit information.

From memory, the Britannia builder struggled when he tried to use 'loose' rivets as you suggest and he found that bronze screws were more successful.

I think most people seem to struggle more with the high melting temperature silver solder and they seem to reserve its use for the smaller fabrications rather than trying to use it for the larger, first stage soldering steps. I think most people try to use the lower temperature solders and use shielding techniques to prevent the melting of previous work. I suppose it depends how experienced you are with silver soldering and what heating kit you have available.

Hope that helps.

Phil H