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Thread: epoxy bonding

  1. #1
    o.O Seggybop's Avatar
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    epoxy bonding

    awesome new forum!

    I'm experimenting with reconstructing a frame from lugs I removed from some trashed frames. I remember that in the past aluminum frames were constructed by epoxying the aluminum tubes to steel joints.

    I would like to try assembling a frame with some unconventional materials (bamboo ftw) but I'm wondering how effective epoxy will be for this? Additionally, what type of epoxy would be best? I don't really know that much about it-- my first thought is JB Weld, but it can't be that simple.

    any aid is appreciated

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    Senior Member Nessism's Avatar
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    JB Weld is popular to glue on carbon rear triangle parts so in this instance, it CAN be that simple.

    Regarding bonding a frame together, it's been done many many times before. Just make sure the surface area of the bonded area is large enough to support the load; you can't just take lugs intended for brazing and glue in the tubes instead because the joint area is too small.

    Good luck.
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    dbg
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    Epoxy is what golf clubmakers have used for years to bond the head to the shaft. I think I've probably done a thousand or more. There are little tricks and tips to get the bond extra strong (roughing the shaft surface, etc). I wonder if the same techniques are used for bike tubes.
    David Green, Naperville, IL USA "The older I get, the better I used to be" --Lee Trevino

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    I work for Lotus cars, bonding glass- and carbon-firbe parts. We use something very similar to JB Weld (Betamate, made by Dow, don't know if it's available retail) for some of our parts, including metal-to-composite bonds. Bonding epoxy would be good too (not the same as laminating epoxy), as long as it's resonably thick (like JB Weld).

    The real secret is prep. To apply the glue to a front crash structure for a Lotus takes about 5 minutes, but the prep takes 25 minutes. Make sure everything is keyed with Scotchbrite (or steel wool), cleaned well with acetone, and preferably primed with an appropriate primer (ask your epoxy supplier).

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    Quote Originally Posted by Jonny B
    I work for Lotus cars, bonding glass- and carbon-firbe parts. We use something very similar to JB Weld (Betamate, made by Dow, don't know if it's available retail) for some of our parts, including metal-to-composite bonds. Bonding epoxy would be good too (not the same as laminating epoxy), as long as it's resonably thick (like JB Weld).

    The real secret is prep. To apply the glue to a front crash structure for a Lotus takes about 5 minutes, but the prep takes 25 minutes. Make sure everything is keyed with Scotchbrite (or steel wool), cleaned well with acetone, and preferably primed with an appropriate primer (ask your epoxy supplier).
    Jonny offers wise counsel.

    Various epoxys have different properties & differing applications. All are not created equal &/or suitable for all applications. As mentioned, JB Weld makes a broad line which is readily accessable to the retial public. Dow is nearly king in some areas, but usually in high end, production facilities, particullarly in the vinyl end of things. It is difficult for the small retail customer to obtain.

    From your original post, it sounds as if you are just messing around. In this case, it may just be eaisest to stick with JB. But check their entire product line, or contact their customer service/rep people for advice, before buying. If you are going to be doing a lot of work, it is worth establishing a relationship with a very knowledgable, experienced supplier. A good such supplier is worth their weight in gold.

    Just my $02. Good luck & have fun with it. Bob

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    Quote Originally Posted by Seggybop
    awesome new forum!

    I'm experimenting with reconstructing a frame from lugs I removed from some trashed frames. I remember that in the past aluminum frames were constructed by epoxying the aluminum tubes to steel joints.

    I would like to try assembling a frame with some unconventional materials (bamboo ftw) but I'm wondering how effective epoxy will be for this? Additionally, what type of epoxy would be best? I don't really know that much about it-- my first thought is JB Weld, but it can't be that simple.

    any aid is appreciated
    It depends on the materials your going up. myself I like an epoxy with a ltitle bit of flex to it. that way it is not brittle and it seems to hold better. I tested joints by gluing two flat pices together then breaking them apart.
    the best easy to get glues were acraglas 9it is a paste type epoxy that works very well. and antoehr oddball was e6000 it is a silicone based glue that is about the most practial stuff to use. but when it can't get air in the joint it takes several days to fully cure.

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    Most "I did this then broke it appart" tests are risky to put too much faith in. Failure modes are rarely the same. Steel is really hard, and we are talking socketed joints, hard should be a real advantagebrazing would be harder, so would welds, ahrd and tough go together at these kind of durometers. Very little epoxy is really brittle where hitting it with a hammer is going to make it shatter.

    Find something that benefits from a heat post cure, that usualy really helps.

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