How did Cannondale make its welds so beautiful? That's what got me wondering about this. In the 1980s, when C'dale was welding aluminium bikes, was no-one thinking about welding steel bikes? Was all the innovation focused on other materials, was steel already musty and tradition-bound by then, at least until the MTB guys came along?
air powered 1/2" belt sanders..
early on the solution normalizing heat treatment left the tubes less than straight,
but the jig held them an alignment