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Grinding welds on the frame????

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16K views 23 replies 12 participants last post by  az1jeff  
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#1 ·
I was talking to someone I work with that welds full time for a living. He expressed how Cannondale grinds their welds for beauty. He feels by doing this it weakens the weld which in turn weakens the integrity of the frame.

I find this hard to believe from a company that's been in the business this long and that has zero problems standing behind their frames. Not too mention, it makes for a beautiful frame !!

Does anyone buy his claim??
 
#3 ·
Cannondale doesn't grind their welds, they are created smooth by the welders. Here is an excerpt from an Dirt Rag article on their visit of Cannondale's factory:

And now a word about Cannondale's hallmark smooth weld bead. It's a common misconception that said weld bead requires sanding to achieve its smooth finish. In fact, the weld bead is smooth, right out of the weld booth. The smooth finish is created by a two-pass, puddle welding technique that Cannondale employs. Cannondale points out that their welding technique produces better penetration than welds that exhibit the typical "stack of dimes" appearance. Better penetration results in a stronger joint. Furthermore, the high and low spots on stack of dimes weld beads may act as stress risers-a potential compromise of weld durability.
 
#4 ·
Anybody out there ever have a weld break on a Cannondale frame? I've had a frame brake after several thousand miles, but it didn't brake on a weld. If there was a weekness such as this, I'm sure we'd hear about it. I'm also sure cdale would quit doing it, as I'm sure it's quite time consuming. At the rate things are going, welds will soon be a thing of the past.
 
#5 ·
rumshcawheely said:
Anybody out there ever have a weld break on a Cannondale frame? I've had a frame brake after several thousand miles, but it didn't brake on a weld. If there was a weekness such as this, I'm sure we'd hear about it. I'm also sure cdale would quit doing it, as I'm sure it's quite time consuming. At the rate things are going, welds will soon be a thing of the past.
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Hu-humm! The welds are not grinded, not sanded, see my above post. Don't worry about the welds, they are more than strong enough.
 
#7 ·
Hey Dan,
I have an old moutain bike or mtb action magazine from when I was going to start mountain biking and was doing research on which bike to buy and it just so happend that the magazine did a write up on Cannondale. They basically did step by step on the how the bikes are made. Grant it, the article I'm talking about is from 1999 or 2000, but getting to the point they told us about the detail that goes into painting the frames and talked about these special sanders they used to give the frames that smoothe weld. They also had a picture of somebody using this device on the frame. I do notice that the welds on the newer bikes are not as smoothe as the older bikes also. Like if you compare my six13 welds to my old Jekyll, You'll see that the welds on the six13 are not as smoothe as the older frame. Is it possible that this practice changed when the ownership changed?
 
#8 ·
Dan Gerous said:
Hu-humm! The welds are not grinded, not sanded, see my above post. Don't worry about the welds, they are more than strong enough.
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I'm not at all worried about the welds being week I have personally battle test Cannondales for a long time! So far I'm pretty darn impressed. Does anybody know why my previous post (about the article I read) got posted out of sequence?
 
#9 ·
rumshcawheely said:
I'm not at all worried about the welds being week I have personally battle test Cannondales for a long time! So far I'm pretty darn impressed. Does anybody know why my previous post (about the article I read) got posted out of sequence?
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They do smooth the welds down still, but it's not for the reason you're thinking.

Because they are already smooth to begin with, they have a higher penetration rate... there are no stress risers (eg, stacked dime welds)

"The minor amount of sanding that the weld beads do receive is done to remove weld spatter and slight surface imperfections. As a matter of routine, the head tubes and bottom brackets are re-reamed to clean out their bore after welding."

if you go read that dirt rag excerpt and the cannondale factory tour (i remember reading that somewhere, but can't remember where... it's not the dirt rag version)
it's all explained...

http://www.dirtragmag.com/web/article.php?ID=831
 
B
#13 ·
I don't know anything about cannondale's puddle welding process, so if it comes off the line that way then all should be fine.

However, grinding a weld will decrease strength in aluminum. Remember, this is aluminum we are talking about, not steel. Sanding, grinding, sawing...can produce enough heat to actually melt aluminum at the joint causing it to oxidize and form Al2O3. This can create porosity and defects that penetrate into the heat-effected-zone of the weld. If great care is taken than I imagine this can be prevented. Even with post-annealing (heat treating) aluminum only recovers to about 85% of its original strength (at the weld of course).

Oxidation has alway been a problem when welding aluminum. That's why it's a PITA and so much care is taken to keep the welding surfaces as clean as possible. If I remember correctly, the first aluminum frames were put together with epoxy because nobody had figured out a good, cheap, process for welding them. I think Cannondale was the first, but I'm sure I might get corrected on this.

From the above posts it seems Cannondale doesn't grind them anyway. Makes this a non-issue.

B
 
#15 ·
rumshcawheely said:
Anybody out there ever have a weld break on a Cannondale frame? I've had a frame brake after several thousand miles, but it didn't brake on a weld. If there was a weekness such as this, I'm sure we'd hear about it. I'm also sure cdale would quit doing it, as I'm sure it's quite time consuming. At the rate things are going, welds will soon be a thing of the past.
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I believe my 06 Prophet 400 suffered a crack in the weld that hold the right hand side forward shock mount to the frame. I say I believe because the actual weld was covered by the paint which cracked. Cannondale replaced the frame under warranty on the strength of photos taken by my LBS. It only took two weeks from the LBS emailing the photos to Cannondale to the new frame arriving on the shop floor. I am not entirely sure that, unless they had seen similar failures before, they would have a) acted so quickly or b) accepted that there was a warrantable failure on the strength of photos alone.

Eitherway, I'm very happy with the way that Cannondale and my LBS dealt with the issue. If the process had been drawn out tho the extent suffered by some people, I would have missed a great days riding at Luchon in the Pyrenees. The Prophet is an awesome descender.

A photo of the crack and other details can be found here:

http://forums.mtbr.com/showthread.php?t=302976
 
#16 ·
Old issue.....For anyone who cares to know the details, they use a hybrid TIG/MIG process. Tig torch, with a wire feed gun. This allows more weld material to be layed into the weld at once, as opposed to the "stack of dimes" style traditional weld. Traditional welds have a sharp coner, or edge, where the weld filler, meets the tube. This creates a stress riser. Therefore, all non smooth welds, will be inherently weaker. Thing is, all the material and process used, so exceeds what the average biker can dish out, both types work fine, and it's really a moot point. Also, Cannondale does use a thin Emory cloth belt to smooth out the ripples in the welds, and smooth the transition even further, for appearence, and longevity. I weld frames, so I understand what it is they are doing, I have been in the factory, and have seen these processes with my own eyes, and I hope that this will help everyone get a better handle on it all. To the OP, tell your welder friend about the process, it may help him get it better, no grinding, no real removal of material, just some smoothing of the final product:thumbsup:
 
#17 ·
az1jeff said:
Don't misunderstand me, I'm not bashing Cannondale. In fact I'd like to know how it happened. I never even would of known it was there had I not stripped the paint. From my eyes, it looks like the metal is just too thin right there. Swingarm is from a 1997 SuperV.
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You're lucky , you're gonna have a brand new CDale frame !

Hope you still have that original bill.....
 
#18 ·
Who really cares what they do? There don't seem to be failures happening all over the place and if any aluminum frame fails after 5 or 10 years of vibration I think that's OK. To get the thing warrantied for life is just a bonus. I have a buddy that had a super v and his ankle angles in, which in turn caused his shoe to rub on the chainstay. After a couple years it wore all the way through. Cannondale warrantied this frame. Had nothing to do with their material and they dialed him in with a new frame.
 
#20 ·
MendonCycleSmith said:
I weld frames, so I understand what it is they are doing, I have been in the factory, and have seen these processes with my own eyes, and I hope that this will help everyone get a better handle on it all. To the OP, tell your welder friend about the process, it may help him get it better, no grinding, no real removal of material, just some smoothing of the final product:thumbsup:
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Hey MendonCycleSmith, could you take a look at that crack on my swingarm? Do you think I can get it welded and use it still? I just assumed it was junk, but maybe you might see that it's not that bad. Thanks, jeff

https://s173.photobucket.com/albums/w58/az1jeff/?action=view&current=crackswingarm2-1.jpg
 
#21 ·
az1jeff said:
Hey MendonCycleSmith, could you take a look at that crack on my swingarm?
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I'd be happy to take a look, and weld it. Issue being, I don't have a way to re-anneal it, which as far as I'm concerned, will make it a less the 100% fix. I've done a few Cannondale repairs, and heard of a a few that have held up , but make no guarantees......
 
#22 ·
I've got a cracked CAAD4 swing arm (from an 01 Super V) sitting in my shed right now, next to a 97 Active 100sl swing arm that is still in excellent condition after 10 years of near constant use.

I got the CAAD4 from a guy 4 yrs ago who was into hucking and cracking Super V's so i'm rather pleased with the time i got out of it before it failed.
 
#24 ·
MendonCycleSmith said:
I'd be happy to take a look, and weld it. Issue being, I don't have a way to re-anneal it, which as far as I'm concerned, will make it a less the 100% fix. I've done a few Cannondale repairs, and heard of a a few that have held up , but make no guarantees......
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I hear ya. Kind of what I was thinking, that it could be welded up, but not at 100%. Probably not worth the risk. Thanks. :thumbsup:

jeff
 
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