Patriot

Yes, it can be done. Even by a Do-It-Yourselfer.

Modern brazing alloys allow this. There is one new alloy in particular worth mentioning. Here is a link to the thread where I just got done repairing my MTB frame. So, for those who think it's imposible to effectively and safely repiar a frame easily, or even at all, you may change your view after seeing this.

I only posted this for others who don't frequent the framebuilders forum to see.

https://www.bikeforums.net/showthread...35#post4476035

AfterThisNap

Alumrepair has been around for decades, and was a staple of "as seen on TV" sales. It's great for filling holes , but to say it's stronger than a proper TIG weld is a little misleading for a couple of reasons.
I know you beat an angled joint with a hammer, but the properties of 2 square pieces of aluminum block are vastly different than thin walled aluminum that already has a head affected zone from TIG welding at the factory and has been heat treated.

Whatev, I hope it works out for you. It looks good.

cryptid01

Of course they're repairable. Here's a few pictures of a repair on the bike of a riding buddy.

before




after

jetta_mike

how did the weld hold up? I imagine that the repair has worked flawlessly.

MtbVA

gastro,

I'm curious, what caused that damage? It doesn't look like riding damage.

Quick_Torch C5

Decent looking weld...obviously not made by an apprentice

pj7

I've been welding aluminum/titanium/inconel/etc for 20 years now. Never really thought that repairing a broken/cracked fram wasn't possible.

Patriot

^^^ I never said that it wasn't possible. However, I hear so many people say that it can't, or should I say shouldn't be done, for any number of reasons. For the home DIY'ers like myself, this provides for a great possibility to make basic repairs without having to pay someone alot of money to do a TIG weld with equipment worth thousands of dollars.

But, like I said in the repair thread. I'm hoping for the best, and the stuff is pretty impressive, but only time and heavy use, will tell.

Quick_Torch C5

Thanks for the link and tips, I may have to try this out one day!

cryptid01

It's taken a year's worth of hucking and racing, no problems thus far.

I believe it was a result of a conflict between the car rack the bike was on and a steep driveway grade.

The repair was made by some local good ol' boys that are pretty handy at fabrication - here's a shot of their shop:

misterC

In many cases, aluminum frames have a warranty with a replacement frame. If you crack a frame, and attempt to fix it, it will certainly not be replaced with a warranty later.

That nice fix in the down tube pictured above I would imagine would hold up for quite a while. A crack in a joint area like the headtube/downtube would probably not fair as well.

Patriot

That repair to the downtube is pretty major, but seems to be holding up really well. The only reason I would ever be concerned about that one, is because the whole area was collapsed and kinked, and the kink wasn't quite fully removed, so it may slowly progress down the road. Other than that, I would see no reason why one shouldn't keep using the frame.

dminor 

hey, thanks for the info, Patriot! That is indeed interesting stuff. This must be a much newer rod than what I remember reading about in Ron Fournier's book. Up to that point brazing was limited to low-stress things like gas tanks and such. Gonna have to check into this further.

When using oxy-acet, are you running a neutral flame or slightly carborizing?

Patriot

I'm using an air-acetylene turbo torch at work. No O2 tank. You can use MAPP gas too.

AfterThisNap

The middle of a downtube is , relatively speaking, a low stress area. I wouldn't trust that weld on the spez, if it were, say, a swingarm joint. Not so much because of the quality of the weld, but moreso for the lack of heat treating after the weld was done.
All production aluminum frames are welded up, then baked at 800+ degrees for heat treating, oil quenched and re-aligned, before being painted or re-heated for a second round of treatment. Aluminum is just so tempermental post-welding. That's why I'm generally skeptical of DIY or even factory aluminum frame repairs at joints.
My next frame is probably going to be steel.

_beaver_

DoYlE_RiD3r

It looks like a tentative to get insurance money
No, just kidding... but it'S a strange place to hit ...

Quick_Torch C5

Mine's the red one on the far wall