Brazing

Just as a point of interest has anybody out there used their tig welder for brazing or silver soldering. It is something I thought about trying when I come to making a boiler for my loco this could save me having to buy heating equipment when I already have a TIG. I have googled the subject and it appears that you can but it would be nice to hear from someone who does use this method and hear of any tips.

Clive

Do not think it is possible to braze or silver solder with TIG as the heat is too localized. Assuming a copper boiler you could always weld it but will need De oxydized copper filler rods, helium as a gas and may need to back purge and as always needs to be clean.

Hi Bob, that's interesting about the tig welding of copper.

you obviously have experience of this, would you share your experiences ?

Brian

Hi Clive ,

take a look at YouTube and search for joining dissimilar metals by oxtoolco , not a boiler but it will let you see tig brazing in action.

Ian

Hi Clive, I can highly recommend watching Tom's videos at Oxtoolco, damn nice chap, he shows TIG brazing/ silver soldering but there is very little capillary flow, which normally provides a lot of the strength, as the heating is very confined to the area of the arc. It does seem to be a very good technique if you want to build up a fillet, Maybe flux would help with making the filler flow but he didn't try it.

chriStephens

hi bob et al - as an ex coded welder who tigs boilers, why on earth would you want to use helium as a gas? I have used tig to sil solder but its not a good idea - if you get too close it reacts very badly and i wouldnt try it again.

Clive,

I would also discuss your plans with your boiler inspector to get his views.

Dave

If you get too close it will vaporize the silver solder/brazing alloy. I don't TIG myself, but I would have thought that heat penetration would not be very deep, therefore the capillary action would be reduced. Ian S C

I have brazed using the old twin carbon arc and a stick welder. Takes a bit of practice but works. Not tried silver soldering with this and don't think it will work very well- to much localised heat. Also good for general heatig eg breaking a rusted joint.

I too have used the carbon arc method with my stick welder, the last lot of rods didn't work too well, they are just listed as gouging rods. Ian S C

Don't gouging rods have a hole down the middle for the air ? I think the quality of carbon rods has gone down, maybe depends where they come from.

Thanks for all your replies. I will give it a go on some scrap some time and see how I get on, as the way I see it is that heat is heat and if I was to play the arc around the seam to raise the temp before hand it may work. Of course thats the theory, as with many operations and set ups in the workshop there is always a plan B or even C.

Thanks again.

Clive

You will need a special rod we use sifalbronze 32 normal sif 1 or 101 isn't interested and likes to behave in a similar capacity to a spitting cobra only with added fumes and flame

again with the silver even using tig but you must use a flux we buy it from thessco ,primarily I tig aluminium titanium and steel bicycles but ironically my actual oxy acetylene leaves far more to be desired than my tig welding skills, I find it easier to tig 0.5wall tubing than brazing it

i will try to post some pictures