welding near brazing. Easy question.
So I have this bianchi road frame with tweaked dropouts that I want to put horizontal track ends onto.
In my life before I moved north, I welded race truck/jeep chassis, so I'm pretty handy with a welder when it comes to general fabrication. Back at home I would have just milled out some of my own ends, cut off the old ones, and TIGed those puppies on there.
Now I'm away from any sort of real shop so at best I'll only have access to an angle grinder and a flux-core wire feed unit. I may get to use a MIG, but it's not "my baby" so I'll be unfamiliar with the amperage and speed settings.
The plan is to cut out the current dropouts but leave the factory "tabs" brazed into the frame with about 1/2" of protursion from the tubes. Then I will cut the flat pre-fabbed track ends to fit the tabs. Grind/weld. Adjust/bend with frame alignment tools as necessary.
I think braze filler melts from 4-800 degrees F. I'll be heating the metal 1/2" away from these joints to 3-4 times that temperature. Will the heat from the welder permanently destroy the factory brass brazing, or will the filler soften then reanneal to it's original integrity?
I thought about filling the seat and chainstays with water before doing this to act as a heatsink. In theory the interior of the tube won't reach above 212 degreees F, so I'm hoping that the brazed joints won't get hot enough to exceed the melting temp of the filler. The heat affected zone of the weld will lose heat fast too though, but If I post-heat it over a torch or stove then I think that the crystalization of the grain structure will be minimized. Plus, it's a bike, not a truck, so the forces will never be high enough to matter.
Obviously,I''ve never brazed before.
I know it seems like a lot of work for an old frame, but it has some sentimental value. Besides, I really have the urge to do some metalwork. Even if it's fisher-price level fab.