# aluminum welding for cracked frame?



## somewhat_absent (Mar 14, 2004)

i've got a cracked 03 RM Switch Ltd. that's a year out of warranty. It blows, I know, so I've been sulking and feeling guilty about thrashing that baby for a few weeks, but now I just want to get back out on a ride! Anyone know anything about where I should go from here? Should I try to get in touch with a local framebuilder or could I just go with a general aluminum welder? I was referred by a local bike shop to talk to Frank the Welder at Sinister Bikes. Any idea on how long this welding would take or cost?

Thanks, and thrash it hard!


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## Maida7 (Apr 29, 2005)

I would go back to where you bought the bike or to the manufacture. Even out of the warantee period a good shop / bike company will make you a deal on a replacement frame. Remember it never hurts to ask.


As for repair, I'm no expert but I would be wary of a repaired aluminium frame.


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## Harold (Dec 23, 2003)

Aluminum can't be re-welded to its original strength like steel can. If you weld it, it will be barely any stronger than not, and you run the risk of a major breakage. I would just replace the frame rather than attempt to repair it.


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## Tracerboy (Oct 13, 2002)

somewhat_absent said:


> I was referred by a local bike shop to talk to Frank the Welder at Sinister Bikes. Any idea on how long this welding would take or cost?


I agree with the guy who said you should talk to the manufacturer, warranty or not. Frank the Welder is legendary and should be able to fix your frame - although if it's 6061 the heat-treating might be a problem. I agree with the guy who said you should talk to the manufacturer, warranty or not. I'd get an estimate for both a replacement and a repair. The manufacturer may let you have a frame at cost,


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## Uzzi (Oct 28, 2003)

As above try and get a deal through your LBS or RMB. I have good experience with RMB... 

I had an aluminum chain stay re-welded and it's still holding up (about two years now). I would however not use that particular bike for anything else but XC and even then I'm worried it will leave me on the mountain some day.

Good luck!


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## WTB-rider (Jul 25, 2004)

Another good reason to ride steel.  

I wouldn't take a chance with welding it, FTW's a master but he ain't a magician.


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## CraigH (Dec 22, 2003)

Pyrotek can do it, but it is probably cheaper to buy the parts from Rocky.

Old article on Pinkbike about it:
http://www.pinkbike.com/modules/news/?op=articleview&id=1117


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## pablobaq (Jun 23, 2011)

theres not much to loose


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## whydomylegshurt? (Jul 28, 2004)

Sorry, I'm a materials engineer and I can't help but to correct a couple things. Steel cannot be welded to it's original strength, there is always a heat effected zone. Post weld heat treatment is usually not required with steel, but the HAZ will have different structural properties than the parent metal.

Heat treating AL isn't as hard as some make it out to be, especially with a swing arm that can fit into a home oven. 6061 heat treatment can be done in the 320 to 350 degree F range, 7000 series AL can be done much lower (room temp if you give it enough time but it is accelerated with temp). You would want to bring the 6061 down to T4 or even T0 after welding to balance the microstructure of the entire swing arm as much as possible, then bring it up to T6. Everything can be done with your oven and a bathtub. If you are married just make sure your wife isn't around with you use the kitchen and bathroom to fix your bike.


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## AZ (Apr 14, 2009)

Must be thread dredge week.


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## whydomylegshurt? (Jul 28, 2004)

Dang, I need to get in the habit of checking the date of the OP not just the most recent post.


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## Prophet Julio (May 8, 2008)

whydomylegshurt? said:


> Sorry, I'm a materials engineer and I can't help but to correct a couple things. Steel cannot be welded to it's original strength, there is always a heat effected zone. Post weld heat treatment is usually not required with steel, but the HAZ will have different structural properties than the parent metal.
> 
> Heat treating AL isn't as hard as some make it out to be, especially with a swing arm that can fit into a home oven. 6061 heat treatment can be done in the 320 to 350 degree F range, 7000 series AL can be done much lower (room temp if you give it enough time but it is accelerated with temp). You would want to bring the 6061 down to T4 or even T0 after welding to balance the microstructure of the entire swing arm as much as possible, then bring it up to T6. Everything can be done with your oven and a bathtub. If you are married just make sure your wife isn't around with you use the kitchen and bathroom to fix your bike.


I had a Jekyll frame welded a few days ago. Cracked at the top tube to seat post weld. It is 6061 T6. I was going to bake it at 175 Celsius for 4 hours. Do I need to do anything else? Someone said I needed to heat the HAZ and quench it. Then artificial aging.


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## archman99 (Jun 24, 2011)

*Hopefull Fix*

]Just got my frame back from the welder. Going to try to get alittle more out of it. I had him install another support tube to add extra strength to the weakened old crack site. Check the pic. Hope it holds. (for my sake)


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## mtbjac (Aug 4, 2011)

*Complete Newbie in need of advice*

Hi everyone

Have been following the forums for a while V interesting. I have a question? My son has just bought a used kona king kikapu frame cos he wants to build a bike from scratch. The frame has been welded right up front where the frame meets forks/handlebar joint. Weld looks clean but he has been told not to risk using it by a guy in a bike store because it is an AL frame and so can't be welded safely. Is this true? and if not how do we check if the weld has been done well? Seller just says he thinks it is fine but will refund purchase price if we are not happy. Son would rather keep frame if possible but will take advice as he obviously doesn't want to build an unsafe bike or sell on an unsafe frame

Any advice gratefully received


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## AZ (Apr 14, 2009)

mtbjac said:


> Hi everyone
> 
> Have been following the forums for a while V interesting. I have a question? My son has just bought a used kona king kikapu frame cos he wants to build a bike from scratch. The frame has been welded right up front where the frame meets forks/handlebar joint. Weld looks clean but he has been told not to risk using it by a guy in a bike store because it is an AL frame and so can't be welded safely. Is this true? and if not how do we check if the weld has been done well? Seller just says he thinks it is fine but will refund purchase price if we are not happy. Son would rather keep frame if possible but will take advice as he obviously doesn't want to build an unsafe bike or sell on an unsafe frame
> 
> Any advice gratefully received


Since the weld is of unknown "pedigree" I wouldn't take the risk. My two cents.


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## sil2222 (Feb 27, 2013)

*Has reapir held up ?*



archman99 said:


> ]Just got my frame back from the welder. Going to try to get alittle more out of it. I had him install another support tube to add extra strength to the weakened old crack site. Check the pic. Hope it holds. (for my sake)


Hey has the weld repair on your bike held up? Please let me know I have a nice frame i want to get repaired thanks.


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## archman99 (Jun 24, 2011)

*lasted for about 10 rides*



sil2222 said:


> Hey has the weld repair on your bike held up? Please let me know I have a nice frame i want to get repaired thanks.


It lasted for about 10 rides. I had a major failure when I was clearing a fallen tree. I was lucky i did not get hurt. It was ugly . It broke in 3 places like a ripped open pop can.Long walk back. If you can afford it. I would buy a new frame.
My KHS frame was about 8 years old when I repaired it. That probably had something to do with the major failure.
Good luck.

Arch


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## fos'l (May 27, 2009)

Wouldn't even consider riding it since the welded area is the worst possible place for a failure.


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## unterhausen (Sep 28, 2008)

a pointer to this thread should be added to the faq since "can I get my aluminum bike fixed" is such a common question


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## bikeabuser (Aug 12, 2012)

unterhausen said:


> a pointer to this thread should be added to the faq since "can I get my aluminum bike fixed" is such a common question


Agreed, it's a common enough question.


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## mudtrek (Aug 15, 2009)

I just finished putting my FSR XC back together. The chainstay completely broke and I had it welded. Looks good. So far, a ride around the parking lot, bouncing the suspension seems to be solid. I have to wait till next weekend to really test it. I'll post back with deets. Oh yeah, I made it a 69'r too. Should be fun.


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## mudtrek (Aug 15, 2009)

Took the bike for a ride today. (Welded chainstay) So far, it passes the novice to advanced novice test. Next week, intermediate to advanced full blown throw down break it test.


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## unterhausen (Sep 28, 2008)

doubt it would break in a few rides. Who welded it? Please report back in a year/and or at failure


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## TacoMan (Apr 18, 2007)

The biggest difference between steel and aluminum is that steel can be designed for an unlimited fatigue life, where aluminum is always destined to fail at some point. Whether that point is within the life of the part is another question. That is why aluminum frames have to be so stiff, if they flexed as much as steel they would fail very quickly.

So if your aluminum frame has cracked, it was not designed/built properly or it suffered a major load which yielded the material causing a stress riser which eventually led to failure.

Bottom line -replace a broken aluminum frame with a better one.


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## mudtrek (Aug 15, 2009)

A little bit of history on this break. It did not occur under "Normal" wear and tear. I beat the balls off this bike. The bearings in the pivot completely fell apart and it snapped in half. So I went to HD, got some bolts and "There, I fixed it"
I didn't plan for it to last too many rides so I went and put a 29r fork n wheel on it to play. Maybe keep it for urban rides. After three light rides, the chainstay snapped. I knew it was going to happen but I started really liking the 69r setup. So I welded up all the parts and tightened up the suspension. I'll ride it some more and If I keep it, I'll get the right parts. 
I like having the "rolls over everything" of a 29r and the speed of a 26r. 
I need more rides to be sure though.

I'm in S Florida and went to a local guy. 
I think he did good work, looks solid. We'll see.


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## unterhausen (Sep 28, 2008)

don't ride further than you can walk back


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## Prophet Julio (May 8, 2008)

unterhausen said:


> don't ride further than you can walk back


Truth! I had an old Jekyll frame welded about two years ago. It is still solid. BUT, I had the triangle re-heat treated post weld. They baked the frame in the oven at 1,050 degrees and after the whole thing was up to temp, they removed it and quenched it. Then they baked it for 4 hours at 450 degrees. That brought the whole thing back to T6 Temper. If you just weld, you have a zone that is very weak. It is called the HAZ (Heat Affected Zone). It is no longer a strong aluminum alloy, but rather it is a soft amalgam of disparate metals that can't wait to break. You can repair a frame, but it costs more than a welder. You have to have it heat treated or you have wasted $ on welding. There are companies out there that specialize in heat treating different metals, so call one who knows about aluminum (know the type of aluminum you have and the temper) and they can help.


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## racebum (Mar 13, 2013)

whydomylegshurt? said:


> Sorry, I'm a materials engineer and I can't help but to correct a couple things. Steel cannot be welded to it's original strength, there is always a heat effected zone. Post weld heat treatment is usually not required with steel, but the HAZ will have different structural properties than the parent metal.
> 
> Heat treating AL isn't as hard as some make it out to be, especially with a swing arm that can fit into a home oven. 6061 heat treatment can be done in the 320 to 350 degree F range, 7000 series AL can be done much lower (room temp if you give it enough time but it is accelerated with temp). You would want to bring the 6061 down to T4 or even T0 after welding to balance the microstructure of the entire swing arm as much as possible, then bring it up to T6. Everything can be done with your oven and a bathtub. If you are married just make sure your wife isn't around with you use the kitchen and bathroom to fix your bike.


best reply ever

i've also welded aluminum and looked into doing repairs, the first being when i was 15

the only thing i will add is that the welder you use has a major impact on the strength with aluminum. i would never attempt to mig aluminum even though some union welder may be able to make it work. using something like a miller syncrowave makes the heat penetration so much easier.

i've personally never had a problem with cracks on aluminum re welds but always used a TIG and quality rod

the absolute minimum level of welder needed to repair an aluminum bike frame is something like a miller diversion 165


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## mudtrek (Aug 15, 2009)

Well so far after some pretty tough riding, I'm still solid. 

Nevertheless, I found a chainstay online and bought it. The weld may be good enough but my piece of mind is worth the few bucks. 

Anyhow, I will never ride a 26" front wheel ever again. I'm in love with the 69'r configuration. I surprised myself at how much faster I can go.

Pfft and I almost chummed up 3g for a new bike.


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## remac226 (Oct 11, 2012)

So how are all of the welded frames holding up? 

I have a Blur XC with a crack near the brake tab on the rear triangle. Santa Cruz no longer has any of the rear triangles and the frame is in great shape otherwise. Local welding jedi says he can fix it but of course we will have the HAZ issues. Girlfriend will be riding this for XC and honestly is not an agressive rider (no jumping or drops). Do you guys think I can get away with just welding it? Should I try to heat treat it afterwards or what do you all think about reinforcing the area with carbon fiber?, fiberglass?, aluminum brazing rod around the area?, JB Weld? 

Thanks in advance!!!!


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## Prophet Julio (May 8, 2008)

My Jekkyl that I had welded back in July of 2011 is still going strong. But I didn't just have it welded. After welding, I had it Heat Treated professionally. For 6061 Aluminum, to bring it back to T6 Temper, it was heated to 1,050 degrees, removed from oven and quenched immediately. Then it was baked at 450 for 4 hours to bring it from T4 to T6.

That is the only way to guarantee a proper repair with full strength.


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## Walt (Jan 23, 2004)

How much do you like your girlfriend? So little that you're going to put her on an old bike of yours (which probably doesn't fit, to boot) that's cracked?

Seriously, folks, if you're not going to do it right (ie heat treat post-welding) don't even bother. Period. Thread closed. 

-Walt


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