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Re: Jewel Box Jr construction question

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  • sirdarnell
    First, drywall screws are brittle and not designed to carry flexing loads so should only be used for clamping. Question if removing screws, is it better to
    Message 1 of 13 , Mar 1, 2011
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      First, drywall screws are brittle and not designed to carry flexing loads so should only be used for clamping.

      Question if removing screws, is it better to just fill holes with epoxy or would wooden dowels dipped in epoxy work better?

      David

      --- In Michalak@yahoogroups.com, "cruising.sailor" <tom@...> wrote:
      >
      >
      > Not to say that anyone should should not go their own way on this stuff, but just to share some ideas on wood/epoxy building versus traditional building using wood/fasteners.
      >
      > After years (40+) of wood/epoxy boat building (mostly unballasted boats, lightweight multihulls from 24 to 38 feet) and repairing three times as many wood/epoxy boats... I can tell you unequivically that the source of later maintenance problems with wood/epoxy builds is 99:1 in the area of metal fastenings used in the construction.
      >
      > True, there will be many fasteners in a boat that will not be the source of problems - but the problems will come in the area of fasteners. My reasoning is that the fasteners produce point loading inside the structure whenever the bending flexing of the wood occurs in the area. This may come from sailing loads, but will also come from thermal loads (as in the deck) where expansion/contraction can produce more than enough movement to create point loads that eventually creates small cracks that migrate to the surface, allowing fresh water to enter the structure - producing rot.
      >
      > Boats engineered for wood/epoxy are dependent on the surface area of the epoxy/wood joint to be large enough to carry the expected loads.
      >
      > Most everybody doing wood/epoxy, even the designers who build, will use fasteners - but for temporarily clamping bits together -- not depending on the fasteners doing any work after the epoxy has cured.
      >
      > Sorry to be going 'rant' here, except you said/inmplied that wood/epoxy was a new are for you -- and for me at least, the most common mistakes I see in newbie boats are:
      >
      > 1) Overbuilding: using thicker/heavier ply or wood -and- using way too much epoxy when doing fillets and glassing. Besides costing lots more money, heavier wood/ply can make getting the boat 'fair' much more difficult.
      >
      > 2) Overclamping (with clamps): applying too much force in local areas and creating unfairness in the finished product, which then needs to be faired. Better, IMNSHO, to use a temporary clamping batten to help get the fairness and spread the clamping loads more evenly.
      >
      > 2a) Additionally, overclamping, even if there's no risk to the 'fairness', will starve the joint of the epoxy that is supposed to be there working for you. Better to work with hairline gaps everywhere and not have to overclamp.
      >
      > 3) Overclamping with fasteners: same as above. if you have to torture the ply to get the joints to close, then there's something wrong elsewhere. It's my practice to dry fit (with the clamping fasteners) and open up touch points (and carefully check fairness with a batten) to be sure I am not fighting the joints when the glue-up begins.
      >
      > 4) Using fasteners inappropriately: adding unnecessary fasteners and leaving in fasteners that were used for temporary clamping.
      >
      >
      > Drywall screws and a dedicated (cheap) portable drill with the phillips bit is you best friend.
      >
      > I would never us nails or ring nails of any type as the corrosion of the metal seems to not necessarily be the biggest culprit.
      >
      > My 2-cents,
      >
      >
      > --- In Michalak@yahoogroups.com, "daraffa" <aikidave@> wrote:
      >
      > > I was thinking of using #14 x 3/4 inch bronze ring shank nails for permanent assembly. Is this a good size?
      > >
      > > Thanks for your advice. These are probably the first of many questions! <grin>
      > > Dave
      > >
      >
    • Hajo Smulders
      I m a big fan of the coated deck screws with the Torx heads. The heads don t strip; so you can re-use them quite a bit. If you forget one, they are remarkably
      Message 2 of 13 , Mar 1, 2011
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        I'm a big fan of the coated deck screws with the Torx heads.
        The heads don't strip; so you can re-use them quite a bit. If you forget
        one, they are remarkably good in not rusting.
        Wooden dowels look neater; but there is no need for them. You can fill the
        screw holes with bog; putty etc... I tend to use quickfair, so that takes
        care of that...

        Hajo
        --
        "Language is the source of all misunderstandings." (Antoine de
        Saint-Exupery)


        On Tue, Mar 1, 2011 at 7:28 AM, sirdarnell <sirdarnell@...> wrote:

        >
        >
        > First, drywall screws are brittle and not designed to carry flexing loads
        > so should only be used for clamping.
        >
        > Question if removing screws, is it better to just fill holes with epoxy or
        > would wooden dowels dipped in epoxy work better?
        >
        > David
        >
        >


        [Non-text portions of this message have been removed]
      • cruising.sailor
        For me, using a syringe pushed right down to the bottom of the hole works best of all. As it gets the epoxy down to the bottom of the hole right from the
        Message 3 of 13 , Mar 2, 2011
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          For me, using a syringe pushed right down to the bottom of the hole works best of all. As it gets the epoxy down to the bottom of the hole right from the beginning of the fill - filling the hole from the bottom up gets rid of the usual air bubbles that cause most of the problems requiring second and third fairings of holes.


          --- In Michalak@yahoogroups.com, "sirdarnell" <sirdarnell@...> wrote:
          >
          > First, drywall screws are brittle and not designed to carry flexing loads so should only be used for clamping.
          >
          > Question if removing screws, is it better to just fill holes with epoxy or would wooden dowels dipped in epoxy work better?
          >
          > David
          >
          > --- In Michalak@yahoogroups.com, "cruising.sailor" <tom@> wrote:
          > >
          > >
          > > Not to say that anyone should should not go their own way on this stuff, but just to share some ideas on wood/epoxy building versus traditional building using wood/fasteners.
          > >
          > > After years (40+) of wood/epoxy boat building (mostly unballasted boats, lightweight multihulls from 24 to 38 feet) and repairing three times as many wood/epoxy boats... I can tell you unequivically that the source of later maintenance problems with wood/epoxy builds is 99:1 in the area of metal fastenings used in the construction.
          > >
          > > True, there will be many fasteners in a boat that will not be the source of problems - but the problems will come in the area of fasteners. My reasoning is that the fasteners produce point loading inside the structure whenever the bending flexing of the wood occurs in the area. This may come from sailing loads, but will also come from thermal loads (as in the deck) where expansion/contraction can produce more than enough movement to create point loads that eventually creates small cracks that migrate to the surface, allowing fresh water to enter the structure - producing rot.
          > >
          > > Boats engineered for wood/epoxy are dependent on the surface area of the epoxy/wood joint to be large enough to carry the expected loads.
          > >
          > > Most everybody doing wood/epoxy, even the designers who build, will use fasteners - but for temporarily clamping bits together -- not depending on the fasteners doing any work after the epoxy has cured.
          > >
          > > Sorry to be going 'rant' here, except you said/inmplied that wood/epoxy was a new are for you -- and for me at least, the most common mistakes I see in newbie boats are:
          > >
          > > 1) Overbuilding: using thicker/heavier ply or wood -and- using way too much epoxy when doing fillets and glassing. Besides costing lots more money, heavier wood/ply can make getting the boat 'fair' much more difficult.
          > >
          > > 2) Overclamping (with clamps): applying too much force in local areas and creating unfairness in the finished product, which then needs to be faired. Better, IMNSHO, to use a temporary clamping batten to help get the fairness and spread the clamping loads more evenly.
          > >
          > > 2a) Additionally, overclamping, even if there's no risk to the 'fairness', will starve the joint of the epoxy that is supposed to be there working for you. Better to work with hairline gaps everywhere and not have to overclamp.
          > >
          > > 3) Overclamping with fasteners: same as above. if you have to torture the ply to get the joints to close, then there's something wrong elsewhere. It's my practice to dry fit (with the clamping fasteners) and open up touch points (and carefully check fairness with a batten) to be sure I am not fighting the joints when the glue-up begins.
          > >
          > > 4) Using fasteners inappropriately: adding unnecessary fasteners and leaving in fasteners that were used for temporary clamping.
          > >
          > >
          > > Drywall screws and a dedicated (cheap) portable drill with the phillips bit is you best friend.
          > >
          > > I would never us nails or ring nails of any type as the corrosion of the metal seems to not necessarily be the biggest culprit.
          > >
          > > My 2-cents,
          > >
          > >
          > > --- In Michalak@yahoogroups.com, "daraffa" <aikidave@> wrote:
          > >
          > > > I was thinking of using #14 x 3/4 inch bronze ring shank nails for permanent assembly. Is this a good size?
          > > >
          > > > Thanks for your advice. These are probably the first of many questions! <grin>
          > > > Dave
          > > >
          > >
          >
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