Richard Isaacs
Senior Member & Supporter
Bronze welding or brazing is a well recognized method of joining aluminum tube Niel and I’ve done it myself to a reasonable standard but that again requires a seriously skilled man driving the torch because it’s all about that perfect balance between getting capillary action going on between the joint but not actually fusing or penetrating the aluminum tube at all.
It’s a weird one because the brazed joint isn’t actually fused it’s a weaker joint than a weld but…….. because the joint also isn’t fused there is no or very little heat affected zone weakening the aluminum mechanicaly and 9/10 when these things fail, it’s not the weld itself it’s the material the weld is fused to right along that fusion line that tears.
You can successfully weld these grades in these thicknesses. A lot of very top end mountain bikes are made from 7000 series aluminum which is loaded with magnesium and very strong. But these are 2 grand and upwards and welded by very experienced professionals. The other thing about these bikes and racing frames both welded and brazed is you’ll notice there is a lot of thought gone into the design to remove loading off the joints.
They triangulate and fit gussets and design it in ways to put the forces on to tubes and strong areas and not the welded or brazed joint making a very strong fabrication.
Sadly our £100 fishing chairs (although made from similar graded materials) don’t get much else in the way they are put together and they will fail if used on river banks with any stress on the joints.