Infusion. How to fix material?

Discussion in 'Fiberglass and Composite Boat Building' started by open650, Mar 7, 2008.

  1. open650
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    open650 Junior Member

    [​IMG]

    And where i must put vacuum line?
     
  2. the1much
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    the1much hippie dreams

    how big is this boat?
     
  3. open650
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    open650 Junior Member

    6.5 meters length and 3 meters width.
     
  4. the1much
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    the1much hippie dreams

    i dont know much about infusion,,well,,hehe,,nothing,,,but,,wouldnt your mold already be split?, or are you going to do it in 1 shot,,instead of doing the 2 pieces separate.,,,,im sorry,,im used to building 45' and above
     
  5. wet feet
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    wet feet Senior Member

    I don't have a copy to hand but there are several ads in Professional Boatbuilder for cans of adhesive for exactly this application.
     
  6. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    There are spray adhesives for this purpose, some are made from solvents and resins that will not affect the strength of the laminate. Others like the 3M spray adhesive are not really compatible with polyester resin and will weaken the part, but they can be used if you're carefull and don't over apply it.
     
  7. jim lee
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    jim lee Senior Member

    To install the vacuum line you need a "resin brake". This is something that air can pass though and resin can't. Magical stuff.

    Lucky for you, peel ply makes a wonderful resin brake. Resin can pass through peel ply from side to side easly, but it has a really tough time flowing along it.

    Here's a mini example of a boat we infused just this last week.

    [​IMG]

    Now, we used the spray adhesive to hold everything together including core etc.

    Along the bottom you can the resin feed line. Its peel ply and some flow material to get the stuff out to the ends in a hurry.

    Along the top edges are the resin brakes hooked to the vent lines.

    To make a vent line; Take a 1 foot wide strip of peel ply and, using the spray adhesive, fold it over a spiral cut tube with a "T" in the middle. Then glue this to the edge of your laminate stack. 1" overlap is good.

    The folded part with the pipe in it should be hanging about 5" from your laminate. This gives 5" of time and keeps the heat of the resin in the pipe from overheating your part when it kickes.

    Oh also, you can't use woven roving for infusion, it doesn't flow. This stuff in the pix is a biaxial glass that's designed to flow. The core was also designed to flow and it speeds things up a lot.

    This hull was infused in 9 minutes. It was the first attempt for this mold. An experement 'cause this mold was never designed to be used as an infusion mold. (Seem's to have worked though)

    A couple things : Make sure you can hold a vacuum on your mold BEFORE you start loading stuff in there.
    You will also need a vacuum leak sniffer for finding those impossible to find leaks.

    Good luck, don't spare the monkey poop, I hope this helps.

    -jim lee
     
  8. Fanie
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    Fanie Fanie

    You can buy some time by working when it's cold and be slightly more conservative with the hardner. Here in SA you have to work either VERY fast of work when it's cold. Winter sounds like the best time to work. Set things up during th day and do the resin late night so it takes longer to go green.

    Someone told me you can suck the vacuum from anywhere, assume you supply in the hull centre you could suck the resin to anywhere from the outsides which is within easy reach. You can also move the supply to anywhere you wish, so it seems if an area begins to restrict flow nothing keeps you from moving the supply point or the vacuum point. More than one vacuum pump sounds like a good idea. The holes are taped close to seal to prevent leakage.

    Haven't done this before nu I'm going to give it a go soon. Already have vac pumps etc. Sure beats a brush or roller.
     
  9. open650
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    open650 Junior Member

    more questions about infusion

    Thanks a lot for your replies!

    to the1much: I will be used only for division of mould because of internal using flange for fastening deck

    During this theme I would like to ask some questions:

    1. How do you think we chose the right construction of mould for use with infusion? In present time our project is working so we can change everything.

    2. to jim lee: As far I understood vacuum line and "resin brake" can be placed over flange?

    3. What is the best way to pressurize the junction between two part of mould?

    4. How can we avoid using much resin in laminate? How much does the special core with grooves increase the weight?

    5. How can we do infusion better: with gel coat or paint part later? Someone said that it was necessary to spray gel coat and then put skin coat manually, and the last one was to stow the rest material and to do infusion. It is said that if we do not do skin coat it will become apparent the structure of fiberglass on the surface of completed part. Skin coat = more weight :(

    6. It seems to me that Airtech buy and relabeled 3M spray seria 77 - this is applicable or is there something better?
     
  10. jim lee
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    jim lee Senior Member

    Typically you -do- put the resin brake on the flange, that is a good spot for it. On my picture we didn't have a flange so we hung them kinda' out in the air. That was a pain! If you can get a flange, do it! They say 6" is what you want for a flange.

    We've not tried a 2 part mold, so I can't help.

    How to not use too much resin?
    #1 Pull a solid 29.9 in Hg vacuum.
    #2 make sure your resin bucket/barrel is not higher than the part your infusing. Level is good. Then you should get the correct amount. Higher can flood the part cause it will be under pressure.

    To gelcoat or not gelcoat and paint later. Paint or not, I'd -always- gelcoat first. Why?

    1 - The gelcoat helps seal up the mold so it does a better job of holding a vacuum.
    2 - Gelcoat also makes the part easier to pull out of the mold.
    3 - Gelcoat seals the mold so the resin under vacuum won't get into the little cracks in your mold and cause the mold to break & chip when demolding your part. We learned this the hard way and I have a mold to fix now. :(

    Skin coat to help the gelcoat? A skin coat is going to add weight, but it very well could save your gelcoat. It seems like its one or the other. For the lighest machine possible you maybe can let it run with print through? Or respray and sand it smooth? We've not been able to solve this one yet. From what we've seen, the print through is the worst over the core. You can almost see where the core pieces are if you get the light right on the exterior of the hull. (But it is light!)

    As for the spray adhesive; We haven't experemented that much with different sprays. Every one says to go sparing with them. One hull here has dry spots and its currently being blamed on too much spray glue.
     
  11. simon99
    Joined: Nov 2007
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    simon99 Junior Member

    hi

    infusion if i can help pls email me at ns_composites@yahoo.com ive done from boats to 47m wind turbine blades
    Regards NS
     
  12. open650
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    open650 Junior Member

    Is it necessary to wait for full drying of gel coat before laying of materails?

    Thank You!
     
  13. the1much
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    the1much hippie dreams

    yes ;) ,,,well,,,at least 24 hours is what we do with hand lay up,,,and if they use the gel to "help seal" the mould,,,then it would have to be cured to do that,,,so i think infusion is same,,but,,again,,,i aint very "cultured" hehe ;)
     
  14. Fanie
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    Fanie Fanie

    The gell coat manuf specify a time at a temperature. If you apply too soon the material may embed in the gell coat and even show on the outside. If you allow to cure completely you could get poor bondage between gell coat and fiberglass.
     

  15. jim lee
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    jim lee Senior Member

    We've tried both. The picture I posted above we actually vented the vacuum bag to CO2 overnight before letting in the resin. The idea was to force the gelcoat to completly kick in hopes that this would give us a tougher cured gel that wouldn't print through so badly. But.. It still had terrible print through.

    Typically, around here, we've been either shooting the gelcoat in the early AM and loading the drystack in the afternoon or shooting the gelcoat the day before.

    -jim lee
     
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