Infusing inwards, double bag and others!

Discussion in 'Fiberglass and Composite Boat Building' started by CristianJ, Dec 14, 2018.

  1. CristianJ
    Joined: Dec 2018
    Posts: 2
    Likes: 0, Points: 1
    Location: Rosario

    CristianJ New Member

    Hello guys,

    This is my first time posting in the forum, i've been reading a couple of interesting threads that gave some new ideas that i would like to try! I wanted to ask first because i see there are a lot of experienced people that may help with this.

    1. I've never tried infusig inwards from the perimeter of the mold to the center, saw a thread from a user that was very satisfied with the results of this setup but most of the pictures that he posted were down. Have any of you tried this and what are your thoughts?
    2. Read a couple of times that people use a "double bag" to reduce the vacuum loss from pinches and others, i can't really imagine how this is done (if anyone can explain it sure help :D)
    3. The last thing is a little dumb but it i've been reading so many contradictory inputs about this that i just have to ask: does it make a difference when the resin bucket is placed lower than the actual mold? some say that it's better to put it above the mold but i just don't know.

    PS: I've done some small pieces in the past but im really trying to learn some more to make a boat with a couple of friends! Thanks in advance for any input on the subject!

    Regards!
     
  2. KD8NPB
    Joined: Mar 2018
    Posts: 47
    Likes: 7, Points: 8
    Location: South Carolina

    KD8NPB Junior Member

    1. as long as it wets out the fibers... We do it both ways depending on the mold design. On narrow pieces, we infuse "across". One side is vac, one side is resin and we pull the resin across the part.
    2. find your leaks! Use an ultrasonic leak detector. double bagging increases compaction, which further drives up glass/resin ratio, which may actually start to reduce strength if you remove too much resin.
    3. i haven't noticed a difference.

    If it was hard, a lot fewer people would be doing it...
     
  3. CristianJ
    Joined: Dec 2018
    Posts: 2
    Likes: 0, Points: 1
    Location: Rosario

    CristianJ New Member

    Thanks for the reply!, good to know your thoughts about the points i asked.
     
  4. JohnMarc
    Joined: Feb 2018
    Posts: 78
    Likes: 3, Points: 8
    Location: Knysna South Africa

    JohnMarc <--- My ultimate goal

    Hi CristianJ, reading your post I was wondering if you have had a chance to put your questions into practice yet, I am a complete newbie to this vacuum bagging process and have recently bought all the kit and just about ready to go. Are you using epoxy, I am assuming that epoxy is the only way to go on a boat but I may be wrong.
     

  5. Steve Clark
    Joined: Jul 2004
    Posts: 188
    Likes: 13, Points: 18, Legacy Rep: 163
    Location: Narragansett Bay RI

    Steve Clark Charged Particle

    It is better to have the resin buckets below the lowest part of the hull, otherwise you can create a siphon and fill the mold with resin. I have never understood the point of the “double bag.” Unless you are evacuating the air between the mold surface and there is no effect.
    We use a “drop test” where we turn of the vacuum to determine how much vacuum is lost in a few minutes. This gives you a answer if there are leaks, even if you can’t hear them.
    You can fill from the edges or from the the center. Experience is the best teacher, sometimes people have to build several test parts.
    SHC
     
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