Beam Pin Vacuum Infusion Help Please

Discussion in 'Boatbuilding' started by Fanie, May 8, 2009.

  1. kroberts
    Joined: Mar 2009
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    kroberts Senior Member

    Fanie,

    Do yourself a favor and work out the torque you are delivering to that pin, and then work out the forces you would need to deliver the same torque to a boat hull. Then, do some figuring to see how strong your pre-glassed boat hull is and how much you will deform the hull by adding that force.
     
  2. apex1

    apex1 Guest

    Maybe the "Plastic" association should redesign their hulls to be produced that way??????????
     
  3. Jimbo1490
    Joined: Jun 2005
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    Jimbo1490 Senior Member

    This is exactly how Boeing is manufacturing sections of the 787 airliner fuselage. It's called tape winding, by the way.

    787 Fuse.jpg

    "Alenia Aeronautica, a partner-supplier to Boeing for the 787, uses a massive Ingersoll tape layer to produce Section 44 of the Dreamliner fuselage. Tape layers are ideal for long courses that allow machinery to reach maximum speed. Most fiber placement projects, however, require a larger quantity of short courses, which is where AFP excels."


    Jimbo
     
  4. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    If someone around here would just think for a change good grief :D I WEIGHED (new concept) the resin tonight before I started the last pin. 3kg +/- 100g. So I'm using 3kg's of resin to 8 kg's of glass. Sounds about right to me. I can do better too if I have a proper made jig.

    Regarding 'tape winding a boat. If you squeegee the excess resin out of the glass prior to laying it, then one may not need such excessive force to wind the glass. The width is also important, a 1m300 glass needs double the force to be wound as tight as a 650mm wide reel.

    Even if the 'mold' or jig bends a little when you wind the glass, I'm sure it will be tolerant of that little bending movement over the length. The beam's jig also bent some, no effect to the pins.

    Such a method may be close to perfect. You tape wind the inner first and around a premade colapsible jig, premade bulkheads in place as well. Then you drape your foam around it and you can tape wind the outer layers the same way. Last layer will be peel ply to help sanding down.

    If you're organised and have a few guys to help you you can do a hull inside and outside in one day. Very little risk of failure and no air leaks and bags to fiddle with :D One doesn't need special resins either.

    Anyway, I'm glad the big pins are done. My fiberglass expert calculated the pins can handle 250 tonnes, in his words, 'very conservative for in case you don't know how to work with glass'.

    The cost saving was worth it. The HDPE pins at 30 tonnes would have cost me > R 4000, while these conservative :D fiberglass at 250 tonne pins cost me about R 1900. I used one reel of glass and less than 20kg's of resin, so there's a bit spare on the R1900 as well.

    Amazingly, now that I have saved all that money, why don't I see it anywhere :rolleyes:
     
  5. apex1

    apex1 Guest

    Why not?
    PREPREG
    is already on the market, at very , very, very competitive rates.
     
  6. McFarlane
    Joined: Apr 2009
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    McFarlane Macka

    good to see apex your looking into pre-preg glass ive been using it for the last 10 years, it does work well if you have the correct oven temps. :D
     
  7. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    The problem is getting a big enough oven to put the boat in.

    When we say SA is hell to live in it's not because the temperature is so high :D
     
  8. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    Finally... a 6 pack :D The un-wetted glass you see on the insides is where the plastic on the former overlapped the glass. I used a block and tackle to pull the glass off the former. Thumb suck about 300 to 500kg's to pull them apart.

    An up close picture of the glass on one of the pins.

    If I am to make a stand alone mast from fiberglass, I would do it using the same method. Inside layer 50% overlap so the inside layer is double, do this twice so you have four layers inside. Then wind uni glass in it's length to whatever requirements, repeat the four layers on the outside. Nice fat diameter and nothing would bend it.
     

    Attached Files:

  9. kroberts
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    kroberts Senior Member

    Yes, but look at the supports they have there so they don't crush their project.
     
  10. apex1

    apex1 Guest

    Thats all you have to contribute? Your usual blabla?
    And where did you use prepregs, on your tugboat in Alaska?

    Fanie
    the closeup shows a perfect surface, I doubt you would have done as good in infusion.

    Regards
    Richard
     
  11. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    Thanks Richard. That was 12 hours well worth spending then.

    The guy with the lathe is full this week, maybe he can cut the pins next week. Have to start on the beams then.
     
  12. apex1

    apex1 Guest

    Well, whats 12 hours for a perfect job. Remember 3 to 5 lbs per manhour is a real good result for amateur building!

    Did you temper them? Or have´nt you used a slow hardener? If you have.... temper them. If there are no spec.s provided by the supplier, heat them up to max 80°C going up from ambient temp. in 5°C steps every 15 minutes, let them sit for 8 hrs., reduce temp in slow steps again. Remember, you cannot "overcook" Epoxy by leaving it on high temp for too long time.
    If there might be no noticeable gain in strength, there is one in high temp stability.
    Fast hardeners usually have no gain from tempering.

    Regards
    Richard
     
  13. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    Hi Richard,

    So, now I'm an ammateur eh :D

    It is a good tip to remember that one can harden epoxy that way...

    I used polyester resin, not epoxy. Polyester resin as far as I know mature over a few months. Heating it would probably accellerate it, but should not be required. The green colour it is currently will turn to a bleak yellow to a bleak white over time. It will be fully cured then, hard as hell and unbreakable. The only thing that remains is to use it ;)
     
  14. apex1

    apex1 Guest

    Well, for a pro you were too slow.:D
     

  15. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    I have to start on the beams... complicated :(
     
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