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Thread: messy welds

  1. #1
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    messy welds

    I am not sure if this is a question for this forum, but since many folks here are welders, frame builders, etc, here goes...

    The frame I am talking about is a run of the mill mass produced aluminum 29er frame ( fisher/trek) I have 2 of them in my basement. A 1st generation version with beautiful welds ( for a mass produced bike anyways), and a 2nd generation (2010) with some of the worst welds on a bike frame I have ever seen. Its so bad, I sometimes wonder if it should be a warranty issue ?

    The area I am speaking about is where the 2 chain stays meet the bottom bracket shell. This 2010 frame does not have a bridge, and the chainstays look formed and stout where they are welded to the bottom bracket. However, it looks like the factory just went crazy with welding material inbetween the 2 chainstays. I am not sure if I am explaining this correctly, but the welds do not "meet" each other very neatly. There are actually divots in the weld which look like tiny holes, or air pockets turned inside out ? It seems to me that water and dirt could actually get inside these holes and underneith the welding ? Like I said, to me it just looks like a lot of weld material just shoved inbetween the 2 stays with no concern for making it neat, smooth, etc.

    Is this normal, even on an inexpensive mass produced frame ? My 1st generation frame uses gussets on the outside of the stays, and there is no weld inbetween the stays. Rather, the welding forms a nice circle around each stay and it looks clean. The newer frame looks messy in that area. I understand its not a custom frame, and its made with cost in mind, but still could this be an issue down the road or a warranty matter ?

    Thanks for any insight

  2. #2
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    Pictures are always nice but really don't think it will be a problem. Welds can be an almost an art form for some high end builders but in terms of function it will likely be fine even if it does not "look" like high art.
    Mark Farnsworth, Raleigh, NC
    http://farnsworthbikes.com

  3. #3
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    yup.

    Function first, then form (a la stack of dimes)

    I rode an AL frame (MTB Hardtail) for almost 10 years that had the *****est welds you've ever seen......but they were good welds.

    Some of these bikes that really have stack of dimes are running the risk of not being complete welds (you don't know until failure because you cannot see under the stack, especially if its a 2 pass)

  4. #4
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    You would be surprised at how strong an 'ugly weld' is, hell some times those ugly ones can be stronger than the pretty ones. At the end of the day it's about penetration into the base mettle, if that is good even with the defects that come to mind from your discretion that frame will last for a very long time.

  5. #5
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    This forum cracks me the fcuk up. In one thread people argue how cheap frames are inferior because of the poor weld quality, and in another someone else talks about how ugly welds are better. Awesome.
    Mind your own religion.

  6. #6
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    Quote Originally Posted by PoisonDartFrog
    This forum cracks me the fcuk up. In one thread people argue how cheap frames are inferior because of the poor weld quality, and in another someone else talks about how ugly welds are better. Awesome.

    I think what they're getting at is that, in terms of welding, 'ugly', and 'poor quality' are not always the same thing. A weld can be ugly and strong at the same time.

  7. #7
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    98% of MTBR users wouldn't know a good weld if it hit them upside the head.

  8. #8
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    Quote Originally Posted by BP73
    There are actually divots in the weld which look like tiny holes, or air pockets turned inside out ? It seems to me that water and dirt could actually get inside these holes and underneith the welding ? Like I said, to me it just looks like a lot of weld material just shoved inbetween the 2 stays with no concern for making it neat, smooth, etc.

    Is this normal, even on an inexpensive mass produced frame ? My 1st generation frame uses gussets on the outside of the stays, and there is no weld inbetween the stays. Rather, the welding forms a nice circle around each stay and it looks clean. The newer frame looks messy in that area. I understand its not a custom frame, and its made with cost in mind, but still could this be an issue down the road or a warranty matter ?

    Thanks for any insight
    I am no welding expert but I know a little.

    I hate to tell you this, but based on your description, that is an inferior weld. The "divots" or pits are a sign of porosity in the weld, and they most likely aren't just on the surface, but rather permeate the entire weld, which therefore makes it less strong.

    Porosity in a MIG weld indicates insufficient use of shielding gas, and should have been ground out and rewelded. The messy "look" of the weld is also an indication of poor welding skills. Its true that some ugly welds may be strong, but based on your description I am willing to bet that is not the case here.
    Mind your own religion.

  9. #9
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    "I hate to tell you this but" there's close to a 0% chance this was MIG.

  10. #10
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    Quote Originally Posted by PoisonDartFrog
    I am no welding expert but I know a little.

    I hate to tell you this, but based on your description, that is an inferior weld. The "divots" or pits are a sign of porosity in the weld, and they most likely aren't just on the surface, but rather permeate the entire weld, which therefore makes it less strong.

    Porosity in a MIG weld indicates insufficient use of shielding gas, and should have been ground out and rewelded. The messy "look" of the weld is also an indication of poor welding skills. Its true that some ugly welds may be strong, but based on your description I am willing to bet that is not the case here.
    Nobody that actually knows anything about welding would make those assumptions based on the OP's description.

  11. #11
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    I've seen a lot of structural aluminum welds done with a spool gun and MIG...

    I don't think that's the best way to join aluminum but it is entirely possible, especially in the cheap mass produced frame market.

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