Brazing question

[Danimal]

Hey guys, haven't tried my hand at brazing a damaged frame yet, but looks like I'm gonna have to. So a basic question for you. Does all the old brass HAVE to be removed? It's a fairly large area of complex shapes and will not be easy to remove it all, let alone flow it back in all the areas. So can you just reflow a joint with more brass?

 

[Sphinx]

I'm certainly not an expert, but I think the possibilities of impurities in or around the old brass might have an adverse effect.You might want to let a couple more people weigh in on this before you proceed.

 

[c.p.odom]

No need to remove old brass but remember it is all about cleanliness. You can burn some impurities out with lots of flux.

 

[Danimal]

Ok, I'll give this a try!

I bought flux coated rods, is that the best? Or should I buy bare rods and separate flux?

 

[c.p.odom]

You want powdered flux to sprinkle on as needed.

 

[Danimal]

Ok then, should I sprinkle it on the metal (the frame) before I start to heat it up too? I assume you can't "Over-flux" it?

 

[c.p.odom]

Spot on mate, and heat the rod and dip it into the flux.

 

[ratcycle]

Could you post photos? It would help some of us out. Also what type of gas are you going to use. I would suggest mapp with a self igniter, and when brazing make sure to heat it up until it is orange almost a liquid.

 

[Danimal]

I'm gonna use Oxy/Acyl torches. I work at an auto dealer and we have them there.

Perhaps a Mapp gas one would work great at home...may have to look into that.

Either way, when I do it, I'm gonna post pics of the job. Hope it all comes out good. I'm more concerned about the metal repair than the brazing itself.

 

[ratcycle]

that's even better. Make sure you use a slighty carbrazioning flame.

 

[Danimal]

You mean run it a bit low on oxygen, right? What does that do for me?

 

[ratcycle]

yes run it until u see black flame, turn it after that. That is how I was taught in college. If you a technical reason I don't have one but you could look it up. It probably has to due with temp. of the flame and the base metal.