Male plug mold release questions? Advice needed..

Discussion in 'Fiberglass and Composite Boat Building' started by Ismotorsport, Jul 8, 2012.

  1. Ismotorsport
    Joined: Feb 2012
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    Ismotorsport Junior Member

    I am about a day or so away from layup and am feeling a little anxiety about getting a good release from the plug. I am using a male plug that was sheathed with ply and csm and then finished with gelcoat surface. *This surface was sanded to 600 grit wet and then compounded and buffed. *Next we used 6-7 coats of hi-low mold release wax as per instructions on can and I plan on also spraying entire plug with partall pva #10. *

    Is there anything else I can do to ensure a good release or is it out of my hands? I am doing the actual hull layup with a epoxy resin with medium hardener (4 hour).*Huntsman epoxy and core cell foam core.

    An additional concern is the plug shape, which has some nearly vertical surfaces being a catamaran hull. The angles are not such that the part will seize onto the plug but more that the release in some parts is more of a shear load than a Direct perpendicular pull load? Any way to proactively handle this?

    Lastly, how do I construct air or water inlets on the part so I may be able help use them for release purposes?*
     
  2. Ismotorsport
    Joined: Feb 2012
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    Ismotorsport Junior Member

    Images of male plug additional notes...

    Additional note: the epoxy and laminates will be layed up directly over the pva without any gelcoat or primer...

    Also how does one build some pull points onto the part for help with release??


    [​IMG]
    [​IMG]
     
  3. midnitmike
    Joined: Apr 2012
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    midnitmike Senior Member

    Ismotorsport,
    That looks like quite a project.

    With proper application of your release agents you should be alright, but like you I'm a bit concerned about the general shape of the plug especially those long vertical surfaces. Have you considered making this a two part mold? Not only will this make your mold easier to remove from the plug, but it will greatly facilitate the construction and release of the parts you're going to pulling from it later on.

    I can only imagine how difficult it's going to be laying up inside such a deep narrow mold let along trying to remove the finished part. A two part mold would have significant advantages in every aspect of maintaining and prepping the mold surface all the way through to the final demolding process.

    If you haven't already you should read this thread.

    http://www.boatdesign.net/forums/fiberglass-composite-boat-building/boat-stuck-mould-43244.html

    MM
     
  4. Ismotorsport
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    Ismotorsport Junior Member

    MM,

    This male plug is being used to build the actual part/hull. I am not creating a female mould for this is a one off project. This is similar technique used to build one off racing sailboats. Any additional advice on some pull point construction tips etc?

    L
     
  5. Ismotorsport
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    Ismotorsport Junior Member

    Note: because this is catamaran hull and there is wing deck attachment the laminates will only go down one side halfway where the wing deck will later join. Only one side will have laminates going all the way to shear line you see in photos. Will this help facilitate release from plug somewhat?
     
  6. wet feet
    Joined: Nov 2004
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    wet feet Senior Member

    The good news is that you have now had some practice at achieving a good surface because you have to repeat the process a couple of times.The bad news is that if you had worked to the outside surface,you could have just laid up a couple of hulls in the mould you had produced.
    If it was my project I would have added a horizontal flange an inch or two above the sheer line to help with releasing the hulls and to maybe act as a vacuum sealing surface if there is any core material to be included.At least with an epoxy laminate you should not be facing any problem with resin shrinkage as the cure completes.I still would have a considerable amount of trepidation about an easy release,but good luck.
     
  7. Ismotorsport
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    Ismotorsport Junior Member

    Water/ air inlet construction

    How does one construct water/ air inlet points on the hull?
    Where are the best locations to mount these inlets?

    This image shows how far down the laminates go on the other side of plug. Just up until the wing deck joint.

    [​IMG]
     
  8. midnitmike
    Joined: Apr 2012
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    midnitmike Senior Member

    I wish I could be more help, but I've never done anything quite like that...sorry.

    MM
     
  9. tunnels

    tunnels Previous Member

    like i said the water will find the path of lease resistance so the keel line is where you will need to release dont touch any where round the gunwhale untill you have released the keel area . brass hose fittings can be moulded in during the skinning and later removed and the holes glassed over and filled completely from the inside . should only need a couple !!.
    How do you intend to lift it completely off when its demoulded !! a hiab at one end and extend the boom right inside and lift and retract the boom if theres enough reach .or simply remove the shed and replace it again for the second hull build !!:D
     
  10. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    If your going to install these lets take a minute to think about it. Since the plug is upside down I doubt you would gain much from using water over air other then to affect the PVA during the release process. It's not like you're going to float the part off like you would in a normal demolding process. If it were me I'd consider installing airline connectors from inside the plug along the keel and anywhere else you think you might have a problem releasing.

    Drill and tap the holes and screw in 1/4" close nipples. You could build a small mainfold to link a number of these together to your air source and either valve or cap them to increase pressure where needed. Simply apply masking tape over the holes on the outside to seal them off during the laminating process.

    Because of the size and shape of your project using air to help free the part from the plug might prove beneficial...and I doubt it would hurt anything...so have a ball.

    MM
     
  11. Ismotorsport
    Joined: Feb 2012
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    Ismotorsport Junior Member

    Almost there...

    Tunnels and Mike thanks for the words of wisdom.
    We pva sprayed the entire plug today, which was tricky over the wax but following your advice I got a nice coat. As for plan for pulling, will be using the posts around plug with cam a longs and an A frame for initial pop,( I hope) and then call in crane to move part to other part of yard and then start again on second hull..... Layup begins tomorrow, hitting the sack. Will post updates later.

    P.S. Did a test panel piece 1 square foot on plug that was prepped exactly the same and had success with release. Fingers crossed. Will add a water or air inlet also. Also added a quick 90 degree flange at shear line all around for stable pulling later. See photos below.

    Thanks
    [​IMG]
    [​IMG]
    [​IMG]
     
  12. tunnels

    tunnels Previous Member

    Good luck !!

    Good luck !!
    Will be waiting for a possitive reply and news that all has gone well for you . !! :D
     
  13. midnitmike
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    midnitmike Senior Member

    Now that's a project! You're last photo gives one a true sense of the size of this hull....and to make it even more exciting there's going to be two of them.

    I'd like to engourage you to consider starting a thread detailing the build.

    MM
     
  14. Ismotorsport
    Joined: Feb 2012
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    Ismotorsport Junior Member

    Successful Release

    Thanks for advice Tunnels and MM. Another satisfied customer of Tunnels pva advice..... Some photos from crane day last week. Now we have to do it all over again :)

    [​IMG]
    [​IMG]
    [​IMG]
     

  15. tunnels

    tunnels Previous Member

    congratulations on the new born !!first of a pair !!

    The second one will be a breeze ! so everything went ok ! obviously !!
    and the weight ? close to where it should be ! there again the second one could be a fraction lighter usually are . In a production situation take 6 boats to get it right after that ist a breeze . so no time to waste and into the next one before the dust had time ti settle !! Good luck !! thanks for the feed back lots people will be smiling !!:D,
     
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