Steve Best
Well-Known Member
Another ancient post drug up for perusal.
Most bikes these days are aluminum or chrome-moly.
Aluminum will require either fitted joints and aluminum braze or MIG or TIG.
TIG is best because it is the only weld that doesn't undercut at the edges.
Aluminum, bronze or silver braze works great if you have enough overlap.
Because the overlap surface area exceeds the material cross section the brazed joint is stronger than the tube.
It gets questionable when you do butt or fitted joints. Fillets are not too bad if cleaned, fitted close and lots of fill.
Chrome-moly will temperature harden at the edge of most arc or gas steel welds.
The weld holds but will crack just outside it. I have experience with MIG, TIG and gas on thicker chrome-moly motorcycle frames.
Fluxcor is garbage for this work, except for maybe a tack during assemble, but no more than a tack.
Braze is my favourite, just don't get the chrome-moly too hot.
MIG and TIG work well with pre-heating and then insulating after the weld.
Proper flaring and fitting so there is enough overlap and no holes.
Thorough cleaning, minimal heat, and slow cooling are the rules what ever you use.
Stick can be done with tiny rods but on chrome-moly it will likely crack on the margin of the weld.
Try pre-heating frame and insulating after weld, but I'm not hopeful.
Most bikes these days are aluminum or chrome-moly.
Aluminum will require either fitted joints and aluminum braze or MIG or TIG.
TIG is best because it is the only weld that doesn't undercut at the edges.
Aluminum, bronze or silver braze works great if you have enough overlap.
Because the overlap surface area exceeds the material cross section the brazed joint is stronger than the tube.
It gets questionable when you do butt or fitted joints. Fillets are not too bad if cleaned, fitted close and lots of fill.
Chrome-moly will temperature harden at the edge of most arc or gas steel welds.
The weld holds but will crack just outside it. I have experience with MIG, TIG and gas on thicker chrome-moly motorcycle frames.
Fluxcor is garbage for this work, except for maybe a tack during assemble, but no more than a tack.
Braze is my favourite, just don't get the chrome-moly too hot.
MIG and TIG work well with pre-heating and then insulating after the weld.
Proper flaring and fitting so there is enough overlap and no holes.
Thorough cleaning, minimal heat, and slow cooling are the rules what ever you use.
Stick can be done with tiny rods but on chrome-moly it will likely crack on the margin of the weld.
Try pre-heating frame and insulating after weld, but I'm not hopeful.