edges of panel under vac

Discussion in 'Fiberglass and Composite Boat Building' started by fallguy, Sep 6, 2017.

  1. fallguy
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    fallguy Senior Member

    Just to share with all the people that contributed; we built a large panel Monday and it had nearly zero laminating defects. Any defect seemed due to variation in core height or perf locations. These parts had high density core insets.

    Here were differences:

    Xslow resin only

    No veil

    Bagged at 70 minutes from first mix of resin; so 50 minutes of open time

    Peelply on bottom.

    Release film

    Ran an extra piece of breather fabric or bleeder up the middle; not sure I will again.

    Full vac the entire time

    I will post the resin amounts I used in a final follow up.

    Thanks to all those who contributed; my idea to align resin times top m bottom was clearly a bad idea.
     
  2. AndrewK
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    AndrewK Senior Member

    Well Done
    All we need now is to get you to do a trial infusion, once you see the quality of the laminate you would find it hard to do anything but infuse when making large flat panels like yours.
    And all achieved without stress, sweat and breathing any resin fumes.
     
  3. Jim Caldwell
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    Jim Caldwell Senior Member

    "Once you try Infusion you will never go back" !!!!!
     
  4. fallguy
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    fallguy Senior Member

    Okay, so I'd like to try to infuse one of the bulkheads. They are about 4' x 6' high. I don't even know where to begin. And that is why I offered to pay someone to show me. But I will try it if I can get some instruction. Do I need to cut kerfs into my perforated core or will it not work with perf'd core?
     
  5. Tungsten
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    Tungsten Senior Member

  6. AndrewK
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    AndrewK Senior Member

    There is plenty of information in previous threads.
    No you dont need to cut grooves, for a trial use the core you have with over the top transfer media.
    You will have better results if you have extra perforations, you have perforations at ~2" centers, make another in between existing plus another row. Only need to be very small diameter and you could use a drill but I find better to use a high tensile steel rod with the tip rounded over. The solid tip from an extendable car antenna is good for this, you can stack a number of sheets together to speed this up as it is a lot of holes. Doable for a small trial.
    Providing your release film is the kind that has many closed spaced holes rather than just pin holes the extra materials you will require is 8-13mm ID tubing that will not collapse under 100% vacuum to be used as the resin feed line, electrical spiral tubing (8mm ID is enough used as the resin distribution line and vacuum line), clamp to be used as on on/off valve on the resin feed tube, and infusion media (shade cloth is cheap and works, ~50% is a good choice to start with).
    If you can source these then we can talk you through.
     
  7. fallguy
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    fallguy Senior Member

    I have found boat building very artsy. More information can become very confusing.

    I think I will put a drawing on here of the part to infuse.

    What type of container holds the resin? It seems a container with a cone at the bottom would be ideal.
     
  8. rxcomposite
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    rxcomposite Senior Member

    I think you are in level 1 of boatbuilding in a scale of 5. In house quality manual sometimes is 50 pages long.

    A lot of info is needed but once you master the use/technique, it becomes second nature, intuitive.

    In infusing, you need only a bucket but degassing is a must so the bucket must have an airtight cover modified so that vac line can be inserted.
     
  9. fallguy
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    fallguy Senior Member

    I couldn't agree with your assessment more rx. I was thinkin about a 3 on a scale of 10 just the other day. I didn't give me senior member title; the host did.

    But it is still an artform.

    Building boats ⛵️...

    If you consider how many production boats even are built poorly; you might agree.

    So; you degas with the same line and run the degas through the part first? Then when the bubbles or a time lapse happens you put the hose in the resin?

    I was warned against infusion for all the potential problems.

    I will work on the materials.
     
  10. rxcomposite
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    rxcomposite Senior Member

    When you buy plans for a boat, the plans will not outline the finer details.

    You can download Lloyd's Special Service Craft and read the first part of Composites, there is a general procedures on composites. Somewhere there is a an illustrated chapter on the method of joints, overlap, connections, ect.

    DNV also covers it but not much in details. ISO is about design but gives some basics.

    We used to write shop manuals that covers from equipment maintenance (compressor, vacuum, spray, hand tools), environment control, material storage, standard shop practices, handling and mixing of chemicals, lamination schedules, core jointings, overlaps and stagger, ect. Things that people in the shop should normally do. These are basics, then comes the craftmanship skills gained thru practice that becomes an art by itself.
     
  11. rxcomposite
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    rxcomposite Senior Member

    You degass by using the same equipment or quick release lines if you want after mixing the chemicals, before infusing. Mixing introduces bubbles in the mix. Fit the cover on the bucket and apply vacuum. If the cover is transparent, you can see the bubbles coming to the surface. With a high vacuum, 5 minutes will do but on some, 15-20 mins is required to reduce bubbles to tolerable limit. It is a compromise so as not to use too much time as the resin has started crosslinking. When infusing, you can still see much bubbles in the resin front.
     
  12. fallguy
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    fallguy Senior Member

    Something like vac bag pressure...a few guys told me never over 14"Hg, but I ran them at full vac. That is artsy.

    By the way, my release film has tiny, tiny holes 10mm apart. Cytex e2760 I think
     
  13. AndrewK
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    AndrewK Senior Member

    The more small holes in your release film the better for infusion, film I use has ~0.5mm hole 3mm apart.
    Will yours work? Yes, How well I dont know your test will determine this.
    Perhaps your first test should be just glass, say 4' x 4' of your triax.
    Containers with a cone bottom would be good, but 10L buckets work fine just tilt at the end to get all resin out.
    You do not have to degas the resin to get good results, I suggest for your trials you deliberately dont do this as this will show you the quality of the laminate at its worst, provided you had no leaks of course.
    Locally most of the guys that I personally know do not degas.
     
  14. rxcomposite
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    rxcomposite Senior Member

    Andrew, I wonder why you changed your position. You have been doing this as you stated in a thread you espoused/participated in
    Infusion Q&A https://www.boatdesign.net/threads/infusion-q-a.30590/page-3.

    And as advised by Herman, same topic,
    "Degassing can be an important step to reduce voids in the future laminate. Not only during mixing you introduce a lot of air, but already during production air is introduced into the resin. It is this air that needs to get out as well.
    For degassing I have a large pan with transparent lid. A bucket with resin is placed in the pan, the lid is put on, and a deep vacuum pump (2 stage rotary vane pump) degasses the resin.

    To help the resin get rid of the excess air, throw a scotchbrite in the resin (and make sure it sinks to the bottom). Another solution is to introduce air in the mixture (which sounds stupid) but the airbubbles will also pull the dissolved air out. (some friends did a subsidised project researching this). For simplicity, I would still opt for the scotchbrite option."

    In which you replied
    "Thanks Herman, I am using a two stage pump and a chamber with a transparent lid.
    I have also read the mentioned article using air or scotchbrite to speed up the removal of dissolved gases. I have not tried the scotchbrite yet only compared the time it takes to degas a mix with a small amount of mixed in air and one with lots.
    The one with lots of air takes longer but as the mentioned article suggest does a better job in pulling out the dissolved gas.
    At this stage I think I will be happy just to pull out the mixed in air as long as I can do it fast enough. Thus the thinking that a metering and static mixing system would help in this regard."
     

  15. AndrewK
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    AndrewK Senior Member

    Hi RX,
    I am not saying NOT to degas, only that it is not mandatory to get good results.
    The less equipment up front and steps in the process the more likely someone new will give infusion a try.

    I also recommended that fallguy only use 60% vacuum for bagging, but did not say not to exceed this amount (at least I hope I didn't).

    In regards to degassing I only tried scotchbrite once and did not notice any improvement. In early stages I was being careful not to introduce air when mixing resin and still am when not degassing. Now most of the time I do degas so do a shorter very vigorous mix that does mix in air but then have more time for degassing. Don't know if the mixed in air is helping with removing the dissolved gases or not.

    I degas until I visually see no more bubbles or when the resin mix reaches 35'C, check with an IR thermometer.
     
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