Things I learned about brazing

And other miscellaneous notes about metalworking.

I'm posting this 'cause it answers a bunch of questions I had that I didn't find enough information on before I dived in and tried it this weekend. I'm building a vehicle for Burning Man, and was originally going to build the frame out of wood, but it seemed like I could do a lighter vehicle out of steel.

And if anyone out there has an old bicycle taking up space in the garage, I need about that much more tubing to finish my frame, cheap steel frames are best.

First, MAPP gas through a normal ($20-30 or so at ACE) torch is hot enough for Weller bronze brazing rods, but it may take a while to heat up the surfaces to be brazed to a good glowing orange. Also, the torch flame is actually hottest pretty far away from the tip, so don't get too close to the working material.

Fluxing well is key. Mixing the powdered flux with a bit of water and applying a light film with an old toothbrush seems to give a decent coat, then periodically passing a rod through the torch flame and dipping it in the dry powder gives enough for spot application. I haven't figured out how you could possibly apply the stuff dry.

Believe it or not, hacksaws are faster than cutting disks. But hacksaw blades wear fairly quickly as well, replace them often. On the other hand, a wire brush wheel on a drill is way faster than wire brushing by hand.

Taking the time to fit a joint more than pays off in reduced brazing rod use, and if your surfaces are actually hot enough to be getting a good joint, gap filling is difficult.

Think about brazing material flow. When the surfaces are hot enough to get a good joint that stuff is going to flow downhill fast.

A clear face mask is quite a bit more comfortable than a pair of goggles, and provides a lot more protection, but I figured that part out back when we were playing with the liquid nitrogen launched bottle rockets.

No idea yet how strong these joints will end up being. I'm trying to reinforce the structure as best I can without making it ungodly heavy.

And eventually I'll have pictures.

Sunday, May 9th, 1999