7005 Frame - Crack Welding Repair- Mtbr.com
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  1. #1
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    7005 Frame - Crack Welding Repair

    I have been browsing the internet for a few days since I cracked my 7005 frame at a gusset weld, which then propagated down through ~1/2 the downtube all within a week or so, this frame is known to crack at this location.

    7005 Frame - Crack Welding Repair-20180927_222802.jpg7005 Frame - Crack Welding Repair-20180927_222817-1-.jpg

    The bike is great, I want to keep it, I ride it hard.

    I am connected with some master AL TIG welders who work on auto racing parts and mountain bike frames. They have both told me that they can weld my 7005 frame no problem and it will be just as strong, it is an advantage of 7005.

    The plan is as follows:

    1) Remove paint and prep weld area appropriately

    2) Weld crack + area around crack, will be a multipass weld most likely

    3) Artifical aging of frame for 6 hours at 200 deg F, then 4 hours at 320 deg F

    4) Spray paint over weld

    I appreciate any and all comments from the frame building community, if anyone has had success stories with welding 7005, please let me know! Also, any failure stories with 7005 are much appreciated as well!

  2. #2
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    There's an area of the crack under the current weld that won't be repaired. Likely that crack will just continue to propogate -- through or around the weld repair.

  3. #3
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    Quote Originally Posted by briderdt View Post
    There's an area of the crack under the current weld that won't be repaired. Likely that crack will just continue to propogate -- through or around the weld repair.
    What if that weld was ground down and then gusset to tube was rewelded? Or the gusset removed, the frame welded, and then the gusset replaced.

    Also - what makes you say that there is an area of the crack under the current weld? It seems like crack has gone along the edge of the weld and then down into the tube itself.

  4. #4
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    Try it, you'll only be out the repair costs. That said, I think you'll only delay the inevitable next failure.
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    Why is that? That seems to be the general consensus amongst people, but I don't see why. Is it because aluminum is designed for so many stress cycles? And if I have a crack somewhere that is fixed another stressed area will just crack as well?

    This frame fails in this area relatively commonly, so my thought is that melting (welding) that area will relieve all the stresses and form a stronger area that before with new multi pass welds on it.

  6. #6
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    Quote Originally Posted by swensonator View Post

    This frame fails in this area relatively commonly, so my thought is that melting (welding) that area will relieve all the stresses and form a stronger area that before with new multi pass welds on it.


    Using that logic the original weld would have eliminated all the stress, no? The leverage of an extended seat post is creating the cracks in the HAZ of the gusset weld.
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    With that logic yes, all of the stresses that I am inducing through riding, any micro-fractures will be melted and reformed as a solid again, right?

  8. #8
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    And rinse and repeat.
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  9. #9
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    Quote Originally Posted by life behind bars View Post
    And rinse and repeat.
    As in I'll just end up in the same place as I am now? Just down the line, and not necessarily soon? That is just the nature of dealing with aluminum?

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