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Old 05-20-07, 04:37 PM   #1
Patriot
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Repairing an aluminum frame. Yes, it can be done.

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.

http://www.bikeforums.net/showthread...35#post4476035
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Old 05-20-07, 08:36 PM   #2
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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.


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Originally Posted by 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.

http://www.bikeforums.net/showthread...35#post4476035
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Old 05-20-07, 09:17 PM   #3
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Of course they're repairable. Here's a few pictures of a repair on the bike of a riding buddy.

before




after
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Old 05-20-07, 09:33 PM   #4
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how did the weld hold up? I imagine that the repair has worked flawlessly.
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Old 05-20-07, 09:41 PM   #5
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gastro,

I'm curious, what caused that damage? It doesn't look like riding damage.
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Old 05-20-07, 10:50 PM   #6
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Of course they're repairable. Here's a few pictures of a repair on the bike of a riding buddy.
Decent looking weld...obviously not made by an apprentice
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Old 05-20-07, 11:15 PM   #7
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I've been welding aluminum/titanium/inconel/etc for 20 years now. Never really thought that repairing a broken/cracked fram wasn't possible.
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Old 05-21-07, 01:00 AM   #8
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^^^ 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.
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Old 05-21-07, 07:29 AM   #9
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Thanks for the link and tips, I may have to try this out one day!
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Old 05-21-07, 07:39 AM   #10
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Quote:
Originally Posted by jetta_mike
how did the weld hold up? I imagine that the repair has worked flawlessly.
It's taken a year's worth of hucking and racing, no problems thus far.

Quote:
Originally Posted by MtbVA
I'm curious, what caused that damage? It doesn't look like riding damage.
I believe it was a result of a conflict between the car rack the bike was on and a steep driveway grade.

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Decent looking weld...obviously not made by an apprentice
The repair was made by some local good ol' boys that are pretty handy at fabrication - here's a shot of their shop:

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Old 05-21-07, 08:26 AM   #11
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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.
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Old 05-21-07, 08:36 AM   #12
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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.
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Old 05-21-07, 09:38 AM   #13
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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?
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Old 05-21-07, 11:47 AM   #14
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I'm using an air-acetylene turbo torch at work. No O2 tank. You can use MAPP gas too.
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Old 05-21-07, 12:02 PM   #15
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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.
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Old 05-21-07, 12:04 PM   #16
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Quote:
Originally Posted by 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.
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Old 05-21-07, 04:18 PM   #17
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Quote:
Originally Posted by MtbVA
gastro,

I'm curious, what caused that damage? It doesn't look like riding damage.
It looks like a tentative to get insurance money
No, just kidding... but it'S a strange place to hit ...
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Old 05-21-07, 09:18 PM   #18
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Quote:
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Mine's the red one on the far wall
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