Installing Screws into Foam Core

Discussion in 'Fiberglass and Composite Boat Building' started by OGM, Sep 13, 2007.

  1. OGM
    Joined: Sep 2007
    Posts: 12
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    Location: Jupiter, FL

    OGM Junior Member

    Is there a recommended method for installing screws into a foam core? For the hard top I'm building I plan on installing an aluminum track for the isenglass enclosure. The track will be screwed into the top and I'm concerned that the skin will not be sufficient to hold the screws. I plan on gluing the track with 5200 also, but I'm still concerned. I could inlay a strip of wood in th foam when I'm building it, but didn't know if there is an easier way. I thought that there was an insert like the ones you put in drywall. Does anyone know about them or have suggestions.
  2. KnottyBuoyz
    Joined: Jul 2006
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    Location: Iroquois, Ontario

    KnottyBuoyz Provocateur & Raconteur

    The wood inlay is a good idea or a high density foam insert. Include it when you lay up the top. Next popular method is to overdrill the holes and fill with thickened epoxy. Then drill out for screws. 5200 is gonna be a b*tch if you ever have to take the track down. 4200 might be a better choice or a foam gasket. Sorry, just that most things I build I have to eventually take apart!! Maybe it's just me!

    post some pics of your project OGM I'd be interested in seeing how you do it.

  3. JRL
    Joined: May 2007
    Posts: 83
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    Location: Palm Beach Gardens, FL

    JRL Im with stupid

    I used SS nut-certs on a set of radome couplers I made a few months back. Sealed the back side with 3M DP-420. Although it was anchored in 9 layers of plain weave E glass.

    Also had good success using those twist in bolt inserts (cant remeber the name). I believe there meant for wood. I used them as the boot anchors in a kiteboard that me and a buddy made. We set them into the foam before the layup. Filled the thread with plasticine. Then performed the layup on top of them. When the glass is nearly dry you cut it away with a razor and then dig the putty out.

    And another way is to use solid fiberglass rod. Cut them to size and counter sink them into the foam (before the layup). When the layup is done drill a slightly undersized pilot hole before you screw into it and your all set. Just make a location template before you start your layup.
    Last edited: Sep 13, 2007
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