Composites 101: Carbon Fiber, Fiberglass, etc.

Discussion in 'Some Assembly Required' started by HickOnACrick, Jul 14, 2011.

  1. Pike Bishop

    Pike Bishop Pull Down the Ponzi.

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    Not for long. UV tears up Kevlar. It needs a UV blocker.
    #81
  2. Orangecicle

    Orangecicle On a "Quest"

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    I took a few weeks away from making CF heat shields and made this. I really, really like it. It's a little SRV and a little space age all at the same time:

    [​IMG]
    #82
  3. tmotten

    tmotten Lefthand ride Dutchy

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    I recently had the opportunity to buy a rally fairing for not to much money and went for it. Got annoyed with the lack of symmetry of mine, although I do enjoy the minimalist naked look of it so I may finish it later once the bike is on the road.
    [​IMG]

    I like this better I think.
    [​IMG]

    So now the plan is to make a quick copy in glass of it to make some adjustments to and make a mould of it. I'm a bit worried about the release of the original part as I've got no room for failure. I prefer to be able to sell it, so I won't even finish the original as there are some issues with the finish. But I guess you get what you pay for.

    So I'm thinking of covering the fairing panel below with 1 or 2 layers of 5.4oz glass and epoxy, not worrying about release angles, let it cure a day and peel it off. I'm thinking it should be flexible enough to pull off. I'll then reinforce it from the inside and use it as a prototype and mould of it.

    Dunno what to do with that vent. It looks good from the side, but jeez it's set back deep. Half thinking of filling it in half an inch deep so it looks like it's there, but it's not. Dunno, it's a tricky piece.
    [​IMG]

    This is looking from the bottom up. The idea is to lift up the edge on the right which is uniform in alignment along the whole edge and pull the prototype from the original. I won't be making the left hand edge as long. Probably half.
    [​IMG]

    My main concern is what to use for a barrier. Had some issues in the past releasing and tried a few different things. Wax, PVA, but by far the easier has been grease oddly. Sure, you don't get the finish, but it works good as a barrier making it easy to pull it off. The difficulty with that is cleaning it all off good enough for the reinforcement glass to adhere properly.

    Anyway, was wondering about wax again, and the reason for buffing it off. Wouldn't leaving it on when it goes all white provide a better barrier?
    #83
  4. tmotten

    tmotten Lefthand ride Dutchy

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    Also, is there a reasonable way of not going through all those consumables? Particularly with waiting for each layer to go tacky which really helps with negating the need for post-cure edge trimming cause I can trim it pre-wetout, I go through a roller with each layer. Seems so wasteful, but a firm roller with cured resin in it is no good either, and going through heaps of acetone isn't great either. Can't really clean the roller that much anyway.

    Just wondering.
    #84
  5. tileman

    tileman Been here awhile

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    Ah symmerty . . . I can so relate. Looks good, I'd go with wax, but my experience is a lot less than yours.

    I like the minimalist look too, shame your effort didn't give you the result you were after.

    I'll be interested once you have finished what your experience with the airflow with this fairing is, beyond that I watch with interest. :clap
    #85
  6. ebrabaek

    ebrabaek Long timer

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    Taco.... While getting the epoxy.....ask the supplier what they recommend for release agent...... I use pva that my alchemist use and sell for his stuff..... Most likely that would work with all epoxys.... But better ask.... the wax`s ONLY purpose is to create a barrier for the pva to release from the piece moulded..... Not the print. If you don't use the wax.....then the pva might take a little more time to clean off. I do not use wax ......well only in rare occasions..... Not a necessity. As far as the angles..... You might get away with one layer of 6`ish oz.....on a sharp bend.... but as you lay down more layers at a time...( wet) it tend to pull more.... ad the shift potential during cure.....and umm.... bring beer or some other anesthetic.....You`l need it....:D.....:clap:clap for starting......
    :thumb:thumb

    Erling
    #86
  7. tmotten

    tmotten Lefthand ride Dutchy

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    Cheers erling. So why isn't it more common to wait till the tacky state for all layers?

    I've managed to cover the plug with pva with a foam brush which was actually much easier than spraying.

    Anyway, somehow I was lead to believe by my surfer mate that one layer should suffice for keeping its shape but sadly not the case. So I'll add another layer on another tacky coat as it spreads our really nice on a tacky surface.

    [​IMG]

    I measured the plug's thickness and it's exactly the same as my proposed laminate at 1.5 mm but I'm not sure what's in it though, other than the inside layer which is 5.4 oz. The whole thing is glass. So my question is, do you get more strength out of more lighter layers or less heavier layers?
    #87
  8. tileman

    tileman Been here awhile

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    I'll start. How much for some copies? :rofl
    #88
  9. ebrabaek

    ebrabaek Long timer

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    Main two reasons..... One....and the most important..... You don`t get as strong of a matrix with the tack.... due to the inevitability of some/lot`s of air replacing resin in the layup = strong but not as strong..... But still pleanty strong for most applications.....
    Two..... Time... Takes more time and makes for a pricy `er piece....... Most people won`t pay for the norm labor.... and since Erlings tack method adds even more time.... you`ve have to charge even more.... Most pieces that I make.... the strength is more than enough..... But lost of people think that the more resin they plow in there... the stronger.... But it`s actually quite the opposite...... How ever.... it is a quite useful tool to bypass the dreaded vacuum system setup.....Don`t meen to step on anybody's toes here...... But many compositours.... Forgets to look/approach this with a beginners view......:thumb:thumb


    Erling
    #89
  10. tmotten

    tmotten Lefthand ride Dutchy

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    Fair enough. I've decided to go with a female mould for this fairing. Will need to cut some of the inside panel for access though, but that's there for aesthetics only anyway. This will make it easier to layup wet and produce a heaps better finish with no worries about degassing.

    What's your opinion on more layers with lighter fabrics vs less with heavier fabrics?
    #90
  11. ebrabaek

    ebrabaek Long timer

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    The thickness of the fabric... Is usually determined by the kinks and crazy angles it has to conform to..... Like thinner fabric conforms easier than thick..... But takes longer labor..... Either is fine.. Like what ever you can get the cheapest.... 90% of my projects are done with 6 ounce fabrics.... ( either carbon fiber or kevlar) It`s a great all around thickness to work with..... I use twill. 2x2. :thumb:thumb

    Erling
    #91
  12. Orangecicle

    Orangecicle On a "Quest"

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    Twill fabric is fairly easy to "bend" around odd corners, like you see on your fairing. Some fabrics, such as the checkerboard pattern, can be really hard to bend around odd shapes.
    #92
  13. Orangecicle

    Orangecicle On a "Quest"

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    I'm looking for a decent vacuum regulator. I've found decently vacuum pumps at reasonable prices, and I'm going to build my own vacuum tanks: http://www.joewoodworker.com/veneering/whybuild.htm

    (borrowed photo)

    [​IMG]


    But now I'm looking for an electro-mechanical valve that will cut off the pump when the vacuum hits about 25" Hg. Any ideas? I started trying to find a good regulator, but the only regulators I'm finding are really expensive at over $200, and that doesn't include a cutoff valve to shut the pump down when the pressure gets high enough:

    http://www.smcpneumatics.com/irv-series.html

    [​IMG]

    Maybe it's cheaper in the end to just buy a more expensive regulated pump? I don't know.
    #93
  14. trackhead

    trackhead Utard Wankster

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    Here's my finished project of a custom fiberglass, pop up camper on my Samurai.
    [​IMG]
    #94
  15. HickOnACrick

    HickOnACrick Groovinator

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    Trackhead,

    This is really nice work. I can't wait to see the inside. Did you use foam as your mold? If so, where did you find pieces large enough?
    #95
  16. HickOnACrick

    HickOnACrick Groovinator

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    I bought a Harbor Freight pump over a year ago. I have used it for multiple projects and it is still going strong. It was on sale at the time for around $130, and I believe building one yourself will cost nearly as much.
    #96
  17. trackhead

    trackhead Utard Wankster

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    Home Depot polystyrene, the pink stuff.
    #97
  18. trackhead

    trackhead Utard Wankster

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    Hey Hick, what do you think of those pumps that work off of an air compressor? I have a decent compressor in my garage already.
    #98
  19. flemsmith

    flemsmith lurk

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    Post # 36 I printed it and was waiting til I actually got the bike running again before I messed with the sidebags. Plastic Enduro's that someone jigsawed an inside corner out of. I've never done any fiberglass work, didn't even know how to buy it. So I read the detailed instructions and gave it a try....unfortunately I was using Bondo gel resin, and it's boucoup thick. It did manage to plug the hole from the inside, but on the outside (which luckily won't show when it's mounted) I still ended up with a thick mess that I couldn't really smooth when 'wet', so I sanded it and went to Home Depot to buy the 3M version, which went on much more like your description.

    http://flemsmith.smugmug.com/Other/Moto-Guzzi-T3/i-FB2PwjQ/0/M/IMG3678-M.jpg

    Here's a pix of the rough dried fiberglass before any sanding or painting. (assuming I did the picture link properly). The green color is from the bondo resin, I can't see using that again.

    The main point is that I really do appreciate the great advice available on this site, For almost any topic! Thanks!

    roy
    #99
  20. redprimo

    redprimo Been here awhile

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    Here are a couple of tips:

    Use large diameter shallow containers vs small diameter deep containers to extend the pot life of polyester resin. epoxy is less sensitive to this.

    You will get better results with spraying pva by not thining it and spraying with a non hvlp gun. The best pva gun I had was an old binks model 7.

    Tape down some heavy plastic over a table and lay your cloth flat to wet it out then pick it up and place it in the mold. On choped and thicker cloth pour/paint some resin on the plastic before placing the cloth on the table. Large pieces of pre wetted cloth can be transered to the mold by rolling or folding up the cloth to avoid streatching and distortion. Doing this will speed things up and can help reduce resin pooling in the bottom of your mold.

    Tap Plastics in California is a great resource for all things composite. their house brand of epoxy is very similar to system 3. In addition to the 3 hardeners having different working times the most important difference is they produce 3 different levels of stiffness.