Flexible fiber glass?

Discussion in 'The Garage' started by gweaver, Jul 25, 2008.

  1. kubiak

    kubiak Long timer

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    heres a pic on the bike.i was worried about fiberglass with the new fuels.i heard they can soften up the resin so i went with steel and used fiberglass resin over the welds just for extra in case one of the welds had a small leak.
    #21
  2. Grider Pirate

    Grider Pirate Long timer

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    Okay, without metal working tools or skills, fiberglass is a good way to go, and you're definately right about the ability to make complex shapes. One 'trick' I've used forever for getting the glass cloth to go (and sort of stay) where I want it is to lightly dust the cloth pieces with 3M77 spray contact cement, then rub them into place on the form before stippling in the epoxy (or polyester). It can be argued that the presence of the light dusting of cement degrades the overall strength, but loss isn't much. When you select glass cloth, you'll want cloth that 'drapes well'. Some online suppliers include quite a lot of information about the characteristics of the cloth, while others just assume you know what you want. (Never a good assumption in my case:rofl ). I often buy from http://www.cstsales.com/
    and also Aircraft Spruce and Specialty. If you can buy your resin/epoxy locally, you'll save on the outrageous shipping costs associated with resins.
    Best of luck.
    #22
  3. notmybikemodelname

    notmybikemodelname KOTW is a myth!

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    That's a good story, have another one?
    I have been in the composites biz for over 20 years (not at the moment though). The best way to do this is to make your plug (model) out of 1-1.5 lb Styro. You will have to laminate it with epoxy as the styrene in polyester or vinylester will melt the foam on contact. DO NOT use carbon fiber, it has no impact strength at all. Your best bet is a comingled laminate of Kevlar/S-glass/Epoxy. After you're done and the epoxy has cured for no less than 7 days, cut your hole for your filler cap and start spraying in acetone to melt the styro. Once you have the majority of it out, pour in no less than one gallon of acetone and swirl and tip for about 20 minutes. Dispose of that, preferably on a bonfire:kboom

    If you want to do this correctly, make two plugs, one about 1/4 inch less than the other in overall size. Use the largest one for your plug for the hard outer tank shell. Send the other off to Fuel Safe and let them make you an internal flexible bladder to go inside the hard shell. This is a fuel cell like structure similar to those used in indy cars and off-road racing vehicles. This will keep the tank from rupturing should you crash and let's you transfer the bladder to another shell if you need to replace the other one after a crash. I have made many of these for race cars, race boats and prototype military vehicles. It's the way to go.

    Your materials source in Cali would be Composites One http://www.compositesone.com/about_us.htm
    For very small amount of material, call Crystaliner in Costa Mesa (949) 548-0292. Talk to Jackie...he's the man!
    #23
  4. fully_geed

    fully_geed Listens to Tom Waits

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    Hi all - Sorry to resurrect an old thread but I am curious about fiberglass fabrication techniques vis-a-vis motorcycle fuel tanks...I'm building a tank myself using a two part (bottom glued to top) process with a female molding process and possibly vacuum bagging the layup although I'm not sure how effective that will be at consolidating the layup with "overhangs" in the mold (that's another story).

    My question is: how much glass is enough for a strong fuel cell? I've mostly worked with 9oz woven glass like this (the twill drapes nicely):

    http://www.tapplastics.com/shop/product.php?pid=84&PHPSESSID=200902131940261569067489

    But perhaps I should use some heavier glass too?

    I was thinking that 8 layers of the 9oz should suffice; your input would be welcome (especially you: notmybikemodelname :)).

    I notice you say "S" glass below...Tap plastics sells something that appears to be of that caliber in the 5-6oz range. Is this acceptable? how many layers would you run and would you vac-bag the assembly to eliminate voids?

    thanks loads for feedback,
    adam

    #24
  5. the_gr8t_waldo

    the_gr8t_waldo Long timer

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    first of all- how "strong" do you want to make it? you can lay up just about any glass cloth enought that it'll resist just about anything! the trouble is that it'll weigh a hellva lot. a foam core will eliminate a bit of glass/weight. the notion that fiberglass is light is "out the window" once you start thinking in terms of "strength". if you'r project is all curves you'll, pretty much have to go with glass reinforced plastic. but if it's flat sided i'd think that aluminum would be a much better way to go.even if your forced to take the sides to a welder, and pay him, his "flat rate" to weld it together. if you still want to do grp flat sided construction, i've done fuel tanks useing gass resitant foam as a core mat'l and laying up one side..then carefully cut out the flat sides, bottom and top. and pin the assembly together ( bottom & all four sides) fiber glass all internal peices together. once you'r happy with the inside, glue the top on. then fiberglass the outside untill you're happy. if you'r intrested in hearing the whole process message me and i'll explain over the phone. i've never used a vacume bagging system, but doubt if it would make the building process easyer. btw voids can be filled after the fiberglass has cured.
    #25
  6. fully_geed

    fully_geed Listens to Tom Waits

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    hey waldo - how does the adage go?

    "Strong, Light, Cheap: Pick 2."

    :rofl :rofl

    I'm mainly interested in strength and understand weight goes out the door with all the resin (I think that's one reason why composites nerds like to vacuum bag);

    If I understand the process you're talking about, it sounds like you build the essential part on a male mold and then cut it off in facets to epoxy/glass back together. Then lots of fairing, etc. I might go ahead with that kind of plan I just figured building from a female mold would allow me to shape a plug that I could build exactly to the bike, including reliefs for the forks and triple clamps....

    I see you're from Tacoma, I grew up in maple valley on the other end of HWY 18. My parents say it has been a pretty wet winter. Hope you're staying dry! PM...

    Adam


    #26
  7. the_gr8t_waldo

    the_gr8t_waldo Long timer

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    i've been working in puyallup at the bottom of a ditch for the last 2.5 months- not dry but i'll muddle thru. what i was trying to explain is a way to built a tank without any kind of mold at all. it follows closely, the "stich n glue" method used in a lot of boat building projects. and is really easy to do in a home workshop.and pretty darn strong construction 2 boot! when done right it produces flat sides and rounded cornners.but the one big problem is my ability to type out the whole process. btw if you want 2, check out "aircraft spruce$speciality" they also have a good selection of mat'l. "S" glass is good stuff, but carbon firberglass is WAY stronger.
    #27
  8. fully_geed

    fully_geed Listens to Tom Waits

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    It IS a complicated process; boat builders are a valuable resource in figuring this stuff out tho! I googled "stitch-n-glue boat building" and came up with this website:
    http://www.pygmyboats.com/Construction.htm

    That's a pretty cool idea, i could see how that could work. Thanks for pointing me in that direction...I PM'ed you earlier today with my phone number. I got my fuel tank cap from aircraft spruce, they're a cool outfit. My dad has an RV-7 and I thnk did a lot of ordering through them...a family of tinkerers, heh.

    OK well i'll read up on this process a bit more...Adam

    #28
  9. DaC

    DaC Been here awhile

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    check out this boatus article:
    http://www.boatus.com/seaworthy/fueltest.asp

    ETHANOL can wreck havoc on your glass tank.




    #29
  10. fully_geed

    fully_geed Listens to Tom Waits

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    Good find, thanks for posting. I wish they would have been specific about what epoxy they were using in their tests; as well as what kind of tank sealers they were using and how they prepped them with the sealer. I could imagine the sealer would not work so well if the tank had already been in service.

    all this is just a round about way of saying: I wish I knew how to weld aluminum :rofl :rofl :rofl :rofl
    #30
  11. the_gr8t_waldo

    the_gr8t_waldo Long timer

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    yes that was very interesting to read...aluminum is looking a lot better. i've never welded al...but how costly could it be to pay a welder to do it? i can buy a finished tank from summit for about 100$ u.s. admitedly it is a simple "all most box "design but that includes two welded vent bungs and two drain bungs as well as a fill cap and welded "L's" to bolt the tank down. you could cobble up a home brew, bench top, "roller sheet metal former" fairly cheaply. if the welder wanted 150 to weld it up for you..that would be cheaper than the more labor intensive GRP. the cost of mat'ls would be far cheaper as well.
    #31