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Thread: Project fibreglass

              
   
   
  1. #21
    Senior Member larryrose11's Avatar
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    Alen, Im using z-poxee, I belive it is a epoxy resin. It is a 50/50 mix.
    I wont say it sands easy, it doesn't. it s tough, but it does abrade away smoothly, and doesn't gum up the sand paper.

    For my application, an RC boat, TOUGH is much more important than ease of sanding.
    To make everything glass smooth (heh) as a final paint prep, Im using microbaloons to fill and build up all the small imperfections and such.
    I love that poop. I mix a small amount of this epoxy Im using, and then mix in enough microballons that it becomes a thick paste. I smooth it out with a putty knife, and give the knife a dip in alcohol and give it a final smoothing. Cures nearly as tough as the epoxy, but sands much easier than the epoxy.

    Friends have told me that pollyested sands much easier, but is also much less forgiving, and easy to crack and scratch.

  2. #22
    Ghost Rider Allen_okc's Avatar
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    Thank You Larry for the info - i only used the resin through out the years and never had any problems, so i know nothing of the poly resin or the epoxy...
    The Greatest thing about a EV, is the Song of the Terrain...

  3. #23
    Senior Member yankee1919's Avatar
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    Hello All,

    If you have a minute there a large section in youtube about fiberglass/composite layup.
    Smooth-on products are a user friendly system that I use. It does not have all the toxic hazards that polystyrene has.
    http://www.youtube.com/watch?v=eh7gtbnkck0

  4. #24
    Ghost Rider Allen_okc's Avatar
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    Thank You Yankee - man thats a bit of a process...
    The Greatest thing about a EV, is the Song of the Terrain...

  5. #25
    Ghost Rider Allen_okc's Avatar
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    im sorry Coninsan, i hope im not stepping all over your thread, if so just tell me to shut the F#@K up... i tend to get excited about threads like this...

    what ever method you use will work, its all good...

    as Coninsan slaps me upside the head...
    The Greatest thing about a EV, is the Song of the Terrain...

  6. #26
    teddillard
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    Can I just say? I hate fiberglass. hatehatehate. (Just thinking about it makes me itch.)



    (And carbon fiber is just a different kind of fiberglass IMO.)

  7. #27
    Senior Member larryrose11's Avatar
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    I think Ted was a surfboard maker in a former life. He has been hatin' on fiberglass since I came on here, despite the fact that he owes it to glass for his R5e tank and seat.

  8. #28
    teddillard
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    yep. If god wanted us to make stuff outta fiberglass he woulda made fiberglass trees. Yeah, that's it.

    Didn't really make any boards, but I sure repaired my share of them and other floaty-type stuff.

  9. #29
    Status-free and luvin' it
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    differences between weaves/mats and polyester/epoxy.. well that's a doozy

    First I will say that every product has its advantages over other choices, just depends on the situation at hand.

    Polyester resins are fine for pretty much any project, cosmetic or structural. They're forgiving in that you can adjust your desired cure time by varying the amount of catalyst. This can work against you however if you tend to add too much catalyst and end up cooking the pot of resin before you have a chance to spread it onto a part. If you use an Isophthalic tooling resin for regular layup, this makes an extremely tough part, which is why it's a tooling resin. Tooling resin is absolutely worth the little extra cost IMO. Polyesters are available with or without a wax added to them which is handy. Resins without wax will remain tacky on the surface to promote chemical bonding of additional layers, only way to get rid of the tackiness is to seal it off from exposure to oxygen. Resins that have wax added will cure fully to the touch which then makes sanding easier, but if you have to add more layers you have to be sure to remove all the wax and sand the surface well to get the best mechanical bond.

    Epoxies need to be mixed with a fairly accurate amount of catalyst, you can not speed up the cure by adding more catalyst. You'll end up with uneven curing or a part that will not cure at all. To adjust cure time with epoxies you need different formulations of catalyst, and most epoxy systems have their own ratios but for the most part you are stuck with the cure times your system of choice offers.

    Epoxies run close to twice the cost of polyester so justifying the cost for most hobby use is difficult given that polyester is adequate for just about anything. Some reasons to justify it though include the lack of smell (Polyester odor is horrid and it lingers for a long time), epoxies wet out and soak into fibers much faster/easier than most polyesters, more chemical resistant, even stronger in a composite than polyester, more flexible/elastic than polyester which makes it less prone to brittleness and cracking. Sometimes a project might be small enough that it doesnt require a large amount of resin so epoxy isnt really much more expensive. Sometimes a lot is riding on a project and epoxy can buy a little extra assurance.

    Either epoxy or polyester are both buggers to sand if the resin is basically straight from the bottle/can. Both can be made into easily sandable light fairing putties with microballoons or fumed silica, or heavy, tough fillers if short milled fibers are mixed in. There are also sprayable, high-build primers available in both polyester and epoxy versions, which are easy to sand and would be the best bet for surface finishing.

    As far as mats and weaves...

    Chopped mats build up thickness/bulk fast which makes rigid parts but the relatively high resin weight vs reinforcement means it's on the weak side. mats are cheap at about $3 per linear yard. Weaves will make a stronger part, and there are thicker heavier woven materials that also build bulk faster, but they're harder to work into tight areas and curve sections.Then there's knytex weaves which is two layers of heavy woven material stitched together along with a chopped mat - TOUGH stuff, builds fast, strong as hell.
    Mike Pipes
    - Currently under analysis paralysis.

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  11. #30
    Senior Member Coninsan's Avatar
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    Allen_okc Don't worry about it, I appreciate getting good advice.

    And Can I say, there is loads of it being dished out here

    Didn't put much thought into the choice of material until yesterday when a mate of mine came out and said that he had some mat and polyester resin from an earlier project, so the choice is obvious.
    But for future fibreglass projects, I'll have this thread bookmarked.

    Got some work done the day before yesterday, just havn't got around to upload the pics yet... heh..
    "I reject your reality and substitute my own." Adam Savage

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