Help! Is this a crack, or a manufacturing flaw?

[Tuckerjenkins]

Good news! The seller has offered a full refund. I've asked whether I can hold onto the frame


A full refund AND you want to keep the frame...???

 

[ForestHill]

Well, I only asked because it's basically unrepairable and I don't want it getting scrapped!

 

[fiks]

It can be repaired, it's going to be quite expensive but still cheaper than a new equivalent frame.

 

[ForestHill]

Yeah, true.
I think my assumption is that I didn't buy the frame for much,so the seller isn't going.to repair it for £150+ when they got less than that for a 'functional' frame
If the seler wants it they can have it, I'm just trying to save it from a skip.

 

[fiks]

Or they could sell it as "damaged, for repair only".

 

[ForestHill]

Yep, they could. As I said, it's up to them, I'm not trying to pull the wool over their eyes.

 

[Citoyen du monde]

The only way that I can see repairing this in a sensible way is to replace the stays completely. At that point it becomes a costly affair. Any other repair puts you in dangerous territory.

 

[Jonny69]

IMHO not so easy to TIG...you can't prep the crack with a V, the stay walls are only 0.6mm thick at the top.

Also, the frame should have been silver soldered (certainly not welded), so any melt or internal flux from the nearby fillet between the stay and seat lug will boil out and contaminate the weld.

753 shouldn't be heated above 40% silver temps, 700Cish. TIG or MIG will take it to 1500C.

All the best,

We'll have to agree to disagree

I'd still weld it. You're right though, it is thin metal and won't V very well. If you went over it with a few spots of MIG and let it cool down in between each I don't think you'd affect the surrounding metal. You could quench it with a wet rag to stop the heat spreading but I don't think you'd put enough heat in to melt the solder.