Has anybody had success in repairing aluminum welds on bikes?

Discussion in 'Cycling Equipment' started by Boxtersushi, Aug 5, 2005.

  1. Boxtersushi

    Boxtersushi New Member

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    Our beloved tandem has developed a crack in one of the welds. :eek: Our mechanic doesn't know any one in the SF Bay Area who can repair it and the company is no longer around. Has anyone had success with a repaired aluminum weld? We've had the bike retrofitted so our 5 year daughter rides on the back while dad hauls her, so it's handling alot less weight than normal. I'm not ready to give up on her:(
     
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  2. artmichalek

    artmichalek New Member

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    Re-welding aluminum frames typically costs more than replacing them. Depending on where and how big the crack is the best option is probably to strip the paint in the surrounding area, wrap the cracked part with two or three layers of carbon fiber, and re-paint.
     
  3. 531Aussie

    531Aussie Well-Known Member

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    a frame builder told me that it depends how thick the area is.....????

    If it's a thick area, such as the bottom bracket, then there's some hope, but I was told that thinner sections are much more difficult to repair.
     
  4. DannoXYZ

    DannoXYZ New Member

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    I haven't had an problems with repairing alloy frames. Picked up a couple of used Cannondales and Kleins with cracks just beyond the welds. The ultra-thin tubing used on those bikes causes stress-risers at the joint where the thin-tubing meets and solid joint. It would be better if they had tapered butted-tubing that flows into the joint smoothly. And grinding down the welds to provide a concave vs. convex lump would spread out the stress-riser as well, kind like shape of the fillet-brazed joints on steel bikes.

    Anyway, yes, it can be repaired, but you have to find a qualified welder. Some standard procedures:

    1. determine actual alloy used in frame and select appropriate filler
    2. fill innards of frame with argon
    3. use high-freq. AC TIG

    Takes all of 30-60 minutes maximum really. Simple way to find a welder that's capable of this job is to ask them if they can weld beer-cans together without blowing holes through...
     
  5. boudreaux

    boudreaux New Member

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    Yeah, and then find a way to re heat treat it if it is 6061.
     
  6. TX101

    TX101 New Member

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    Done properly, it should be as good as new. Manufacturers use welding to build the bike so you can also use welding to fix it! The problem is finding someone skilled enough to do it properly. Most people will TIG weld and back purge with argon, but you can also gas weld aluminium with the right filler rod & flux.
     
  7. boudreaux

    boudreaux New Member

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    Yeah baby!! And after welding they are heattreated. 6061 heattreating is a complex high temperature process. 7005 is less ctitical.
     
  8. lumpy

    lumpy New Member

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    I'd suggest you contact some aviation or marine welders. They have to be the best as lives depend on them. :eek:

    I had a racing kart repaired at a marine welding shop shop in Princeton - by Half Moon Bay - and they really new their stuff. They spent a lot of time determining what grade steel the frame was made of so that they'd weld it properly.

    Call "Alan Steel Supply" in Belmont and see who they recommend.

    good luck!
     
  9. terravelo

    terravelo New Member

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    I have a Santa Cruz Blur frame that developed a crack in the seatube weld at the bottom bracket. The frame is built out of 6061 aluminum that would require heat treatment after a welding repair,so that option is out. I've seen some sites online (Durafix is one), that sell welding rod that is used with a propane torch. The operating temp is around 735F which is below the annealing temp of 775F. Has anyone tried this or know of anyone who has?
     
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