Fillet Brazing

We build bicycle frames out of steel. And fillet brazing is our thing (or bronze welding as it’s sometimes called). Why? Because it’s the most versatile way to build steel frames (we can set the angles of the joins ourselves), and it’s what Brian knows inside out and backwards. He’s famous for it. You’ll come away from one of our courses being able to join any two tubes together any way you want to. So you’ll have more skills at your fingertips than if you’d learnt to build a frame with pre-made lugs.

Lugged vs Fillet Brazing

Lugged steel frames have a kit of parts: steel tubing and specially (pre-made) sockets, called lugs. Frame builders cut the steel tubes to the right length, mitre the ends and put them into the lugs. Then they braze (solder) the lugs and the tubing together, filling the gap between the two with a silver or brass filler metal.

Fillet brazing (or bronze welding) is a way to make bike frames without the lugs. Frame builders cut the steel tubes to the right length, mitre their ends and then, using a brazing torch, melt the filler metal into the join, which creates a fillet between the two tubes. Fillet brazing gives us a bit more freedom because it means we don’t have to rely on the angles set by lugs. And it’s what Brian is famous for.

What does fillet brazing look like?

Here is a photo of Brian’s fillet brazing, Brian only ever cleans the flux off the joins (as pictured below) but some people like to file the braze to make it look like the tubes blend together once painted. You can do either.