Tich Small Boiler Joint question

I apologise first of all for the lack of proper terminology, however can someone help me out with the following. I am currently building a small boilered tich as per the original words and music. The original design calls for the boiler to be formed from copper sheet and the boiler barrel to be formed into shape and overlapped by 1/4" and riveted by 1/16" copper rivets prior to silver soldering. The examples I have seen on the internet seem to all have a thin (approx 1/2" wide) copper strip placed over the joint which is left flush and then this is rivetted into place (double butt joint?) prior to silver soldering. Which is the best method to use and why do the boiler examples on the internet use the addition of the copper strip if this is not mentioned in the original plans?

Dave

On a seperate note, I am aware of the issues with the boiler with regards to the threaded stays and the lack of bushes on parts of the boiler and will deal with them when I get to them.

When I built my small boiler Tich I overlapped the boiler joint by about half an inch and silver-soldered it, in accordance with the instructions that you quote. This makes a good joint but it makes the fitting of the smoke-box end tube-plate and subsequently the boiler tube into the smoke-box a little more difficult as the end of the boiler can not be formed into a circle. The boiler -> smoke-box joint must be airtight.

The use of a lapped strip over a butted joint is more in keeping with modern practice and makes the fitting of the tube-plate and then boiler into the smoke-box with an airtight joint easier.

Regards,

Phil

hi dave,

you need to discuss the boiler longitudinal joint with your club boiler inspector. these days an outside butt strap is preferred rather than an overlap joint.

cheers,

julian

Hello Dave,

I prefer the interior butt & strap joint, for the reasons mentioned, . . . with qualifications. The only riveting absolutely necessary is what is required to hold the joint in place and keep it snug during soldering. Otherwise there's essentially no structural benefit from the rivets - it's all in the solder. For that reason it's important to get complete solder penetration to this joint and to do this, in addition to keeping the surfaces scrupulously clean, I file a slight relief angle (creating a "V" ) on the abutting edges of the barrel. This V helps admit and distribute solder along the joint. I also file a solder port (wide spot) every inch or so along the joint, likewise to provide entry points for the solder. I also grind (by Dremel, etc) shallow solder paths in the solder side of the strap to help solder wick to the edges of the strap. Tiny details I admit, but this will help insure a sound joint.

Edited By GWRdriver on 18/12/2015 14:26:18