Infuse two sides foam at once

Discussion in 'Materials' started by MassimilianoPorta, Nov 14, 2019.

  1. fallguy
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    fallguy Senior Member

    Can someone pm me the stack and method to infuse if I have perforated core? I don't want to hijack, but super curious and already have wet bag core. I would be able to do one side at a time if needed. I would be infusing 12mm Gurit M and 17 oz or 1708 (if needed for the infusion) for catamaran walls that are not integral to the hull. I have a vac table 4x16'. Thanks.
     
  2. Eric ruttan
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    Eric ruttan Junior Member

    Friend,
    Why are the male plug? Is flat against the table no good? Seems simpler.

    If you want defined/sharp corners, run strips around the layup? Makes resin flow 'up' and into discharge, making the 'well' flood with resin, and easier to see dry areas, if any.

    Advanced mode! Lay a flat sheet of MDF/whatever on top,and a bag on it, after infusion, when you know it is well wet out. Vac sheet onto layup. Nice flat top, squeeze any excess resin, and IF you have occluded dry spots, they gone.

    Did you do a test? How are you sealing the bag?
     
  3. AndrewK
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    AndrewK Senior Member

    I can give you a general guide for resin consumption but you should test your materials and create a spreadsheet to calculate the resin for each job accurately.
    Stitched glass; 50% of weight
    Peelply; 40g/m2, this is for light weight ~60gsm cloth
    Foam surface; 600g/m2, ie 300g each side. Grooves and perforations depends on the core, 520g/m2 for the core I used.
    Feed line and distribution line; calculate the volume of your tubes.

    Remind us again why you want the MDF plug, also no need for the release film assuming the table and MDF is sealed and will be waxed or pva release used.
    Also don't forget a large resin break on the vacuum side.
     
  4. MassimilianoPorta
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    MassimilianoPorta Junior Member

    Maybe I have not been clear (sorry but english is not my first language...).
    I sketched a cross section of what I would like to achieve. Plese see picture below.
    Basically is a flat rectangular roof top for my boat with "extended" borders for extra stiffness, and I can't imagine any other way to achieve this but using an mdf (or XPS foam) plug.
    ttop-xsection.jpg

    I am more than open to change process (wet bagging?) or approach if you think a better/easier result can be achieved in any other way... please suggest.
    AndrewK thank you so much for the general guide for resin consumption!
     
  5. MassimilianoPorta
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    MassimilianoPorta Junior Member

    This is the current roof top the previous owner installed.
    20190727_140352.jpg
    It is a very heavy hand laminated plywood core weighting 50 Kgs / 100 lbs.
    My goal is to replace it with something in the range of 10 Kgs/20 lbs.
    It has not to be walkable, just has to support the radar mount (which has a counter plate below), the solar panel and thermal camera etc.
     
  6. AndrewK
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    AndrewK Senior Member

    You said that learning to infuse was your objective, provided that you already have a high vacuum pump (100%) then give it a go.
    But if your pump is not capable of full vacuum then do a wet bagging job.
    Your finished panel is going to be more than 10kg, more like 15kg if you use 600gsm laminates. Reason is that you need high density inserts under the hand rails and radome.
    You can also do the reverse of the plug, narrow border profile, less material required.
     
  7. MassimilianoPorta
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    MassimilianoPorta Junior Member

    Thanks Andrew!
    Sorry I did not get the mail this thread got an answer :-/
    Yes my pump is a two stages 100% vacuum pump.
    Could you suggest what could I use as a high density insert under the hand rails and radome?
    Also I can't visualize the reverse of the plug, how could I build it?
     
  8. AndrewK
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    AndrewK Senior Member

    Inserts can be anything that will not get crushed by the bolt loads. Most expensive 200kg foam, cheapest plywood. You could also do a talc and resin bogg mix, you would fill the holes in a number of stages to avoid excessive exotherm.
    Another option is to see if you can get expanded pvc board off cuts from a local plastic sheet supplier.

    The reverse of the plug is to have a border of say 100mm wide mdf planks plus the radius corner infills.
     
  9. MassimilianoPorta
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    MassimilianoPorta Junior Member

    I think I will use the talc and resin bogg mix as more flexible, thank you!

    Now I see it and I will for sure use this approach on a rod holder project which will do next this one. Thanks again!
    For this one I am thinking about replacing the MDF with EPS board, 30 mm thick.
    Easier to cut and to round corners... could it work?
     
    Last edited: Jan 29, 2020
  10. AndrewK
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    AndrewK Senior Member

    Yes the EPS board will work.

    If I was doing this my self I would simply rebate the top edge of the core, make the flat panel alone.
    Then using a right angle aluminum extrusion as a mold make the edge piece, two most likely. Then glue these on to the board, to go around the corners notch out the top of the angle. Use a heat gun to soften the laminate to go around the corners.
    Very easy to fair flat surfaces so I probably would not bother with trying to get two finished smooth surfaces in one hit, but I have a propeller sander that makes fairing of the top surface very quick.
     
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  11. MassimilianoPorta
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    MassimilianoPorta Junior Member

    Andrew thank you!!
    Your creativity is amazing to me, I have to come to visit for an extended training!! :D
     
  12. fallguy
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    fallguy Senior Member

    I, too, would build three panels.

    Rebate the outside edge of the core or both edges of you like, then glue the side panels on.

    I would also make the side panels one inch of core thick. They are so small, the gains from vac bagging are rather incremental.

    Radius a one inch core side panel on three sides with a nice wide radius with a router. When you laminate that edge; if you have trouble keeping the glass down; you can wrap it with plastic and tape; just keep the plastic dry.

    I don't think the prior owner was wrong to use the ply. It is darn handy as a core as it requires only bedding for holes. A foam core needs thixo or inserts.

    If you think you are going to get it to 20 pounds; that is really not valid.

    The three panel method will be heavier than a single layup. But I think your 20 pound goal is a little unrealistic. I would probably make it from 25mm core, personally. Then I would probably buy some aluminum tubing to use as inserts. Just make the inserts really rough on the outside when you epoxy them in or they can slide out under bolt pressures. I did some and wish I had filed grooves into the sides of them.
     
  13. MassimilianoPorta
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    MassimilianoPorta Junior Member

    Thank you Fallguy!
    I am rather new to composite building and a plug approach looked the simplest to me.
    Tomorrow all the materials will be delivered and I will give it a try... if unsuccessful I will use the other approaches AndrewK and you suggested.
    Wish me luck! :)
     
  14. AndrewK
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    AndrewK Senior Member

    Hi MP, have you done any test infusions? if not yet it would be a good idea if you did a trial full length of your job 1500mm.
    Only needs to be 200mm wide and can be anything, no need to waste your good core if you can not make use of the test panel.
    Can be cheap polystyrene, plywood, timber plank, anything that you can drill and put saw cuts in the same as the core.
    Most important thing with infusion is not to be tempted to infuse even with tiny leaks. Make sure you have a perfect seal and you will be impressed by the quality of the laminate.

    good luck Andrew
     

  15. MassimilianoPorta
    Joined: Apr 2019
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    MassimilianoPorta Junior Member

    Hello Andrew!
    So far I prepared "everything" and I have to say I am a little concerned (scared) about this first job... it is very big seeing it live!
    Very tempted to do a wet layup instead of an infusion...

    20200208_191433.jpg 20200208_210429.jpg 20200208_210433.jpg

    Will do for sure a test run (also for the thickness of the fiberglass), thank you again for the advice!
     
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