Harris wrote ;
> If you will,please clarify.Copper filler?Do you mean steel filler
> that is copper plated to prevent corrosion in storage?Which those
> tacking of steel tube blotches most likely are.Just questioning.There
> probably is a copper filler for tig welding copper......
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Nope, not a copper coated steel filler (the copper burns off the steel anyway) but a bright copper coloured filler indicating something with a very high copper content. Copper filler rods were once commonly used for braze-welding copper tanks and other low-temperature non-fusion joining of copper-copper, copper-brass (vis 'Cuprotectic copper-phosphorous alloy rod')
It has to be something with a higher melting point than the bronze/brass filler used to do the main brazing of the lugs lest it would in theory fall apart. Silicon-Bronze as an example of a main filler has something like 60% copper in it and melts at around 875-895 deg.C, high-copper allloy rods are over 90% copper and melt at just over 1000 deg.C, and pure copper 1085. My guess is they use filler rods leaning at the 90 plus per-cent end of the range, and these surely would look predominantly copper coloured when brazed on.
p.s. Asking an Engineer is as bad as asking three scientists. You'll get three answers, and three outcomes, (all in theory correct) then expect the project manager to make a decision) Who we really need to ask is one of the assemblers who used to work at, for example, Lenton Road. (No P.C. it's not a cue to tell us the vurtues and values of Raleigh's finest)
Bob Reid Stonehaven Scotland
http://www.flying-scot.co.uk (mapped)