Hei guys, a frind of mine asked me to fix a crack. My plan is to place a lumpy fillet over the crack, whole way arround. Does it work? for some time? or is it necessary to replace the tube? thanks for help and all your ideas
I wouldn’t be completely confident in anything that I did there, but that wouldn’t stop me from trying or offering advice.
What I would do is drill the ends with a small bit, chamfer and clean the crack of rust, then fill it with silver and file it smooth . Then I’d make a gusset or two that bridged as much of the crack as possible, ideally all of it. I would fillet pro braze everything together and file out the transitions from fillet to tube.
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That’s an extremely difficult thing to fix with just a fillet, since you’re essentially trying to “butt-weld” two ends of a tube together, and you’re not going to be able to get the two mating surfaces clean or properly fluxed. A fat bronze or silver fillet will of course add some strength, but you’ll still have a crack underneath that will most likely be a new initiation point for a crack in the new fillet.
Best solution is a new tube, so that you have a proper joint with no pre-existing cracks underneath.
Next best solution would be to TIG weld over the crack and existing joint, so that you’re melting the crack into the base metal, in theory, and adding a bit of material via additional filler rod. Not guaranteed to hold forever, but very likely better than a brazed fix.
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I agree that tig alone will fail less quickly than brazing alone.
I suspect that both of those solutions will fail in short order. A brazed butt joint is weak. I’ve had a similar crack repaired with tig before I learned how to build frames, and it lasted about 3 months.
Short of replacing a tube, the only repair that stands a chance of lasting is a steel bandaid capillary brazed over the top of the crack, then fillet brazed.
That could also work, but I think the difficulty would be in making the patch follow the crack along the joint, due to the weld fillet.
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Absolutely. It would be small fiddly work that’s hard or impossible to hold onto in a vise.
And the patch won’t actually bridge the crack, unless you file or grind away the weld fillet.
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Might as well replace the tube at that point.
I trying to build a sleeve. all way arround. i cleaned the crack and filled it with silver. next step i trying to place the “sleeve” aroung the tube wich connect also to the round flat area. i will show you some pictures tomorrow.
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