Corecell M for Stitch and Glue

Discussion in 'Materials' started by sinjin, Jan 16, 2012.

  1. sinjin
    Joined: Jan 2012
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    Location: Georgia

    sinjin Junior Member

    I'm contemplating building a plywood stitch-and-glue design using CoreCell M80 instead of plywood. Can anyone who's worked with CoreCell M80 (or any CoreCell product, for that matter) tell me if it can be bent at least as easily as plywood of the same thickness? I'm aware that it can be thermoformed, but I'm not sure I would continue with this thought experiment if that turns out to be necessary. I really want to know if I can bend it around the same male molds that I would bend the plywood, and get a similar shape/result.

    P.S. I'm already in the process of (dis)validating the weight justification for doing this, including determining the required layup schedule.

    Regards,

    David
     
  2. CatBuilder

    CatBuilder Previous Member


    You can bend Corecell more easily than plywood, actually. You can get something on the order of deck camber without even heating it. You just have to hold it in place somehow while you are laminating it.
     
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  3. tunnels

    tunnels Previous Member

    Know the product you are using , understand what it can do !!

    What kind of a radius are you talking ?? foam bends heaps easyer then ply wood the same thickness ! Its even if you put one layer of glass on the outside of the foam it will bend a nice even curve as it has no grain or hard and soft places anywhere . and the glass hold a little tension to make it fair and true .
    Can bend just plain glass sheet as well . One layer of 600 gram double bias is magic to bend ,800 gram double bias is good also just use on a bigger curve ,2 layers of 450 gram chopped strand is easy to bend ,one layer you can almost tie in knots . Unidirectional matt 400 gram is even better still and you could wrap it round a 44 gallon drum . Remember the tighter the radius the sooner you have to get it off the mould and do what you have to do and let it cure to that shape !Will stull retain a little tension but thats a good thing as it make the panel naturally fair .
    I used to make origami fold up panels to do the interiors on some boats and it worked well . The whole panel could have maybe 10 to 15 corners, internal and external in the whole length of a panel !!
    Comfortably the smallest radius is about 50mm dia just use the right glass in the corner you want to bend main thing is to use peel ply and make the glass a uniform thickness or it wont bend properly if its an uneven thickness !:) smallest radius i have made was round a 60mm pipe size , Make it flat and when has gelled pick it up and wrap it and hold till its cured . When making any kind of glass panel to bend make sure you use peel ply to get a smooth surface on the inside as well as the outside , This is a case where neatness counts as always !!.
    Biggest problem i have found with trying to use heat to bend foam is you have to be quick and the hotter the foam has been heated the more brittle it becomes . so have found lots other ways to do what i have to do and dont use any heat at all .

    Try wrapping 18mm H80 divinicell round a cone shape when the small end has less than 80 mm radius and the other end of the sheet is about 400mm radius and not using any heat !! Its really easy !!
    Theres a brain teaser for all you experts !!
     
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  4. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    How would you stitch the one side glassed foam panels together ?


    Will the scarf joints or butt joints, in the one side glassed foam panel bend fair and stay intact ?
     
  5. CatBuilder

    CatBuilder Previous Member

    I'm not sure you could do it well with one side glasses panels. If you did, you would risk delamination and leave a lot of residual stress in your panel. You'd then need darts like a Kelsall build uses to bend glassed foam.
     
  6. tunnels

    tunnels Previous Member

    :idea:You can simply lay it on a flat surface and pack up under two sided for a cambered top then glass and let cure the top side . to make a dish pack all sides and laminater the top surface cover with a sheet of plastic and add water till you got the shape you want . let it cure and drain ,flip it over the pack up the middle to the shape you want and laminate the top ! . Making shapes is only limited to your imagination as to how you make them . You need to live in places where they think creatively and how they are going to make it work !!, not the million ways you cant make it work !simple is best and work 99.99% of the times .:confused:
     
  7. tunnels

    tunnels Previous Member

    Size of boat ?? shape of the boat ?? got any pictures ??post something to look at !!! what sort of radius is the tightest ?? Build panels inside formers not over !! make glass foam panels with the glass side outside and the foam inside stitch it the same as if it was plywood !
    Think what you can do not what you cant do !! its nothing new !!
    Glass and foam will bend easyer than ply the same thickness . Darts and cuts ?? what for ?? making more work for your self !! or are you trying to get a flared bow ?? Think simplicity !!!! :p

    CatBuilder you need to get some adventure in your life and look around a little more and take note of what and how jobs can be done without all the bull crap and saw dust !!.
     
  8. tunnels

    tunnels Previous Member

    specially for cat builder !!

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    PS: Just the fact that I sent it to you should make you feel good.
     
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  9. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    It sounds logical.

    Does it save build time over plywood ?

    Ply is very easy to use and cheap.
     
  10. Herman
    Joined: Oct 2004
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    Herman Senior Member

    Great post, now let's help the topic starter.

    I have no idea of the size of boat you are making, but very likely you would like to make panels that are larger than a sheet of Core-Cell or PVC foam.
    As the foam is more flexible than plywood, curvature is not a problem. Actually you would like the panels be a tad more stiff. Which is when laminating one side jumps in. (already mentioned above)

    There are 2 ways of making these panels:

    -1. is the simple way.
    Take a large sheet of a suitable material (can be melamine board) and make a table large enough for a needed sheet.
    Apply wax
    Lay glass fabric and impregnate
    Lay down Core-Cell sheets
    add weight, use vacuum or whatever.

    -2. is the more complicated way, which is suitable for the more weight conscious builder. Basics are a table again, but shape the foam core more exact, and recess the edges, so any outside tabbing can be faired without using too much fairing compound.

    There are 2 simple ways of doing that. If you like the idea, I could elaborate further. Let me know.
     
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  11. tunnels

    tunnels Previous Member

    Use a thin sheet of a MDF board or what ever and cut the shapes you need and make two panels one for each side to that pattern !!, you will have very little waste !! step the foam core back from the edge 50mm on all sides and it can have the edges all way round tappered nicely and ground to shape so when its all in place can be glassed over and all joins in the chines the transom and up the bow and the keel can be doubles up with a few extra layers of glass for good measure . Carefully grind and sand a slight recess for the outside layers of glass but if you are really clever and thinking ahead when making the panels you can mould a recess into the outside and then use peel ply and its just tear the peel ply and hand sand and there is the recess also moulded so after the layers of glass have been applied its pretty will close to the level of the actual panel .
    With any thing to do with Glass work its always thinking away ahead of what you are actually making !! ,almost vizulise the finished product and think backwards from there . I do the same with the planning of any job !!, I work backwards from the launch date and then you dont forget anything and you have a schedual and time frame of where you need to be at any given time . And people will wonder why you are so well organised !!;)

    Making simple panels with thin foam never use weights !! vac bag always !! dont need a lot of vacumn just enough to hold the foam firmly in place till the resin has gone hard . Always make sure you use perfirated foam when using sheets so resin and air can bleed out to the top surface every where over the whole panel . :D
     
  12. tunnels

    tunnels Previous Member

    Save time !! mmm
    what will you do with all the time you have saved ?? sit for hours watching mindless tv programs !!
    Building a boat even if it takes a year is never a of waste time ! Sheet of ply wood ,sheet of fibreglass, sheet of aluminium , sheet of steel ,sheet of titanium ! a sheet of what ever it dosent matter! its the method of stitch and tape thats the important of this excise . :D:p:p
    Ply maybe cheap and easy to use but to get it to the smooth shiney finish of a fibreglass panel made to shape with very little waste ! how will you go about that and how much extra time and materials will you have to use ?? What you save on one thing you could spend 4 times as much to get to the end product of what you will get naturally if you use fibreglass ! .
     
  13. rberrey
    Joined: Oct 2010
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    rberrey Senior Member

    With stich and glue the bend of the ply from frame to frame developes the shape of the hull. Foam may not do this, so you would have to develope the bend with battens. A male form with wood battens or pvc pipe battens would allow you to use the foam . rick
     
  14. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    What are the implications of having the glassed side of the corecell to the inside of the boat, rather than the opposite way ? Either way, there seems to me to be a likelihood of problems obtaining a fair curvature where foam sheets meet one another. And it needs to be borne in mind that a core glassed on one side only is quite 'floppy' till the other side is laminated, much more so than ply.
     

  15. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Thats an advatage of ply....its stiff and lies fair on the molds.
     
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