bonding plastic and fiberglass

Discussion in 'The Garage' started by sailah, Jan 6, 2013.

  1. sailah

    sailah Lampin' it

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    I am building a project bike and one thing I want to be able to do is extend the seatpan to allow a more comfortable seating position. The seatpan is on the Ninja below and my hand is approx how far I want to extend it. I don't have any idea what type of plastic it is, but its fairly flexible and smooth. I've used adhesive like 3M 5200 before and that stuff seemingly would stick to anything and was a nightmare to get off, nightmare:deal.

    [​IMG]

    Here's about how far I want it to go

    [​IMG]

    Underside

    [​IMG]

    I am planning on making the extension from fiberglass and epoxy but I don't expect the epoxy to stick to the plastic. I was hoping to either mechanically fasten it with rivets maybe or some badass adhesive that will hold the part to the original seat pan yet remain flexible enough to allow some slight movement as you would encounter on a seat.

    The extension and original seatpan will be properly supported all the way to the subframe so this is just to hold parts together. Suggestions? Esp from McMaster since I seem to order from there a couple times a week.

    Thanks
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  2. Unstable Rider

    Unstable Rider Moto Fotografist

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    Might be a good application for carbon fiber. Strong as shit and the goo might bond better to plastics, but I am not sure. There are a couple excellent CF threads going on ADV, some of those guys are real rock stars with that stuff, they would know.

    Great post, just the same.
    #2
  3. the_gr8t_waldo

    the_gr8t_waldo Long timer

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    if possible, i'd go with 3M9485 in the 5mm thickness adhesive( about 25$ for a 60yard roll X1/2"wide).. this is a tape composed of just adhesive on a coated peil off paper strip. the bonding surfaces must be clean before using this 3m product. and the more overlap the better. this 3m product should be applyed to the entire mating surface(only one side need be covred). and once set and allowed to bond it's permanet! i'd sweeten this with two pop rivits, to insure that the parts are alined,before the two parts are allowed to make contact, and that some pressure is applyed for the bonding to take place. full bonding takes place a in about 24hours of close contact... not a cheap project, but anyone who uses this stuff comes away impressed with the ease of handling and a first class repair.
    #3
  4. therivermonster

    therivermonster Been here awhile

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    Hey Sailah! You have an interesting project going on there.

    I have a little bit of composite experience, and it is my experience that a good epoxy resin will stick very well to just about everything; even plastic if it is prepared correctly.

    How do you plan on laying up the extension of the seat pan?

    Are you going to make a mold of sorts?

    Have you ever worked with fiber glass before?

    Your pics are great, and your post has been very informative so far, but if you could include a few more details on how you plan to create the composite part, that would be of great help to those of us who might have some answers.

    I'll keep an eye out for your next post.
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  5. mouthfulloflake

    mouthfulloflake Not afraid

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    It has been my experience as well, that epoxy resin will bond to sanded and cleaned plastic.

    polyester resin will likely not work.

    the 3m 5200 is great stuff, but i think you would have to prep the seat in the same manner as epoxy resin to adhere, and the 3m5200 takes, what 10 days to cure in warm climates?
    #5
  6. sailah

    sailah Lampin' it

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    Thanks guys. I have a reasonable about of composite experience used to work for a large custom yacht builder that did SCRIMP infused hulls plus I have built a number of small craft using epoxy. I have a gallon of west epoxy, carbon cloth, kevlar, mat and some light weave cloth. I don't plan to make a mold this will never be seen, just layup right over the part.

    I'm no expert though. My experience with epoxy is that it will crack if flexed. Maybe that high strength tape would be a good choice after I layup the part.

    I'll probably keep the build thread updated if folks want to help with suggestions
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  7. Anorak

    Anorak Woolf Barnato

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    Plastic welding? Find a body shop that does it, perhaps.
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  8. sailah

    sailah Lampin' it

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    I have a good friend that owns a plastic welding company, I'm sure he could help but I was hoping this could be done much more simply, and he's 2 hours round trip.
    #8
  9. the_gr8t_waldo

    the_gr8t_waldo Long timer

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    5200 will be more forgiving because of"not perfect" surface matches. and can always be picked up at the local marine box store.- just something to consider
    #9