tim
Active Member
Posts: 32
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Post by tim on Nov 14, 2004 21:16:06 GMT
hello
Iam about to start building a steam plant for a model boat and just trying to think ahead abit , the boiler and end plates will be of copper what will be the best way to join them ? brazing with copper rods or silver solder it.
all comments welcome (apart from anything to do with model boats only joking )
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Post by the_viffer on Nov 14, 2004 21:25:22 GMT
Well the obvious response is don't start from here but Easiflo No 2 silver solder would be a fine bet in the alternative.
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tim
Active Member
Posts: 32
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Post by tim on Nov 14, 2004 21:49:33 GMT
hi the viffer
i will need to silver solder some brass fittings, safety valve ect at some point . but copper to copper is brazing stronger ?
cheers tim
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Post by the_viffer on Nov 14, 2004 22:45:44 GMT
If you are adept at TIG and can get the right grade of copper then yes copper to copper is stronger.
We ordinary mortals find Easiflo is strong enough and easier to apply for all joints on a copper boiler. Unless you re doing anything really outrageous (and if you are well done) I'd go for silver solder
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SteveW
Elder Statesman
Posts: 1,456
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Post by SteveW on Nov 18, 2004 22:18:47 GMT
Re using TIG for sticking boilers together: I have heard that many boiler testers won't touch a TIG'ed boiler.
The advantage to a silver solder/brazed joint is that the joining metal flows down though the joint to produce a very strong result. A weld on the other hand can be just skin deep but look perfect. Also any stress will focus in the thinnest place, i.e. usually the weld.
Silver solder is also available in a range of temperatures so start with the hottest melt and and work down.
Brazing is very good except you need a hell of a lot more heat to get the brass filler to melt.
Finally, as with any soldering operation, cleanlyness is next to Godlyness. If the joint isn't completely clean it just won't happen and generally once you've melted the solder into the join you need a lot more heat to get it out (if at all). Also, don't silver solder if there is any trace of lead/tin solder around because at silver soldering temperatures lead/tin solder will alloy with the copper and convert to fresh air (it'll melt out).
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Post by the_viffer on Nov 21, 2004 22:01:33 GMT
Only one of the clubs I belong to has a rule on TIG welded copper in boilers which is a one liner (as compared with the reams of stuff on other issues) saying if you use TIG then you have to prove the copper is deoxidised.
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