Tig Brazing - Give up and go with Oxy/Propane ?

[Premiershipman]

Been trying and failing miserably to tig braze effectively on dissimilar metals.

I am using the SifSilCopper 968 which is great to brazing copper or steel, but I am trying to braze brass to copper and having a nightmare.

By the time i get enough heat to braze the two, I have overheated the brass and made a lot of zinc fumes !!

I am wondering whether to invest in an oxy propane brazing set ? I appreciate Oxy Acetylene is considered to be better for all round use but as I have a Portamig, Lorch T220 and Hypertherm I don't need it for cutting or any other jobs.

Also, i am not wanting acetylene due to the cost given that a bottle of propane from a local supplier has no daily rent, especially as I am just a hobby welder !!

I think that a gas based brazing systems would be better for brazing copper and steel than my tig setup so it would just be the rent for a bottle of oxygen (£7 a month ?).

Any advice / suggestions ?!

Shady

 

[mike os]

brass is always going to be a problem to braze because the melting point is so similar to the filler..... best bet would be silver solder I would think

 

[hotrodder]

Dunno which flavour of brass you're using but FWIW the melting point of the TIG brazing wires including CuSi3 (SIF 968) is higher than most brasses including oxyfuel brazing wire

Oxygen is available rent free from most of the usual suspects, a few offer rent free acetylene too... more expensive than propane which'll do everything acetylene can except weld* however the way the heat is distributed within the flame makes acetylene nicer to use a lot of the time- heat is more concentrated in the primary flame (nearly double that of propane) whereas propane produces most of it's heat in the outer flame (more than double that of acetylene)

* acetylene uses O2 from the surrounding air to complete combustion in the secondary flame, this results in a shielding effect for welding which brings us to mixture ratios- propane usues several times as much O2 as acetylene

 

[Premiershipman]

The biggest issue I have is my location which means no rent free options !!!

I know the tig brazing can be done but I just end up boiling the zinc from the brass before I get anywhere. I am not interested in gas welding so the option of oxy propane seems a better price alternative.