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 Post subject: Strip built core?
PostPosted: Tue Jan 06, 2009 11:46 pm 
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Location: Lebanon, NH
Thinking of attempting this for a 135x41 TT. What type of wood? Thinking some combo of ash, cedar, and spruce strips. What about a core thickness (same as strip thickness in this case)? Leaning toward a max thickness of 12mm with the tips and edges thinned. Glass layers/weights? Not sure how a core like this will react and how much glass it will need. I'll be making the core first and then hand laying up the glass layers. Thanks.


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 Post subject: Re: Strip built core?
PostPosted: Wed Jan 07, 2009 12:25 am 
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I don't think you would need a lot of glass, more in the transverse direction, the lengthwise wood grain having some inherent strength. Even so, it sounds like heavy construction, but attractive when finished.


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 Post subject: Re: Strip built core?
PostPosted: Wed Jan 07, 2009 4:39 pm 
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Sounds like you have a good idea.
Not necessarily too heavy -you can probably stay under 3kg.
I would do cedar or other light stuff, maybe with a center section of some strips of stiffer wood.
Laminate should not be all that different from "normal." Which probably means around 12 oz carbon or 15-20oz glass, I think.


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 Post subject: Re: Strip built core?
PostPosted: Wed Jan 07, 2009 5:49 pm 
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Joined: Thu Jun 07, 2007 9:08 am
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Location: Ljubljana, Slovenija, EU
Oj, been working ower the holidays on similar thing (finaly some time), I usualy try to make boards out of the comman stuff. 2 different types of wood here -soft edges (25% of length which is actually over sized skim 130x54 cm, mirror TT)

http://picasaweb.google.si/matej.merkac ... 1668845970

you can still se on picture the stuff that was soft brushed off, hands last
board ready now for vacum ...

I decidet not to put anything on top, 2 layers of carbon under and thats it, soak top with epoxy and than see depanding on weight and flex. Wood is actualy a spruce tree, slovenian and african (called Marupa..basicly same thing to ours just lighter.maybe more flex) so just hoping to stay under 4kg.

has a 3 cm concave so i want to keep the flex in all directions. + additional rocker (no cheating)

I say just go for it, but apply in 2 stages the glass, to see after some days what flex vs stiffness
u forgot to tell: startded with max 1cm before even tuching it with el. grinder.


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 Post subject: Re: Strip built core?
PostPosted: Wed Jan 07, 2009 6:25 pm 
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Joined: Wed Nov 20, 2002 1:00 am
Posts: 893
Location: rhode island
12mm (1/2") planks of cedar will be significantly stronger and stiffer than a comparable thickness of plywood, especially if you mold any concave into the shape.

the 12-15 oz cloth needed over more conventional foam cores could easily be reduced to 4 oz or less.

do a survey of the folks that have built their own copy of the MAKO.
Addiction kiteboards in Oz ( if they still exist) are strip-built pawlonia, which is lighter than cedar.
i dont think he uses any glass

lay up the core and see how stiff it is before you add any glass.
the math to 'guess' the added effect of any laminate is pretty simple.

no matter what happens, it will be pretty to look at.

regards,
-bill


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 Post subject: Re: Strip built core?
PostPosted: Wed Jan 07, 2009 6:58 pm 
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Location: Ljubljana, Slovenija, EU
do a survey of the folks that have built their own copy of the MAKO.

I have 2 more friends and we all made lots copies of mako, i was the only one foolish enough to make the first one ot of foam (lost it before having a chance to brak it-nooooooo) than all latter ones were of layered light playwood. I like riding my flex make, but must know that is a different board to ride from original.
went into strip-building just to play around with flex (this year), dont care if the board is not perfect,
Next strip core: a bit larger skate for strapless fun in light wind flat knee deep watter.
will see how they work in summer


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 Post subject: Re: Strip built core?
PostPosted: Wed Jan 07, 2009 8:53 pm 
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I've been doing a bit of Googling on the topic of wood cores lately as I want to make another full-wood core board but am designing this one in CAD. I'm new to CAD so the first one I'm doing in 3/8" plywood just to save time and money. From what I found you can go a bit thinner (12mm) with a full wood core because it is stronger, and as zfennell mentioned, you won't need nearly as much outer glass reinforcement. The production ones mention poplar a lot as well as spruce. Maybe lay it up so that the denser woods are under your feet and the lighter wood is out at the edges and tip/tail for lower swing weights.

Most info I've found has the tips thinned down to about 3-4mm.

With a 12mm core thinned down to 4mm at the edges I'd start with a single 6oz. deck and single 4 oz. layer on the bottom. If it's not stiff enough you can put another 4oz. layer on the deck.

You could also do a 12mm balsa core and just put 2 layers of 4oz. both sides.

All laminates are purely wild-ass guesses though. I've got a 3/8" ply board with single 4oz. both sides and the thing is bulletproof, but it's not thinned out at the tips at all.


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 Post subject: Re: Strip built core?
PostPosted: Thu Jan 08, 2009 3:33 pm 
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Joined: Sat Feb 02, 2008 6:10 pm
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Location: Lebanon, NH
Thanks for all the input guys. Thinking that I'll probably go with a 12mm core thinned at the tips and edges and probably go with a layer of 6 oz and 1.5 oz on both top and bottom. One more question, what are your thought on rails for this core? ABS/PVC, wrapped glass rails, or just shape the wood core and seal with epoxy? What is the best way to do a wrapped glass rail using a hand layup with no vacuum? Is fiberglass tape (1"-2" width) the best material for wrapping the rails? Thanks.


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 Post subject: Re: Strip built core?
PostPosted: Mon Feb 16, 2009 9:32 pm 
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Joined: Thu Jun 07, 2007 9:08 am
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Location: Ljubljana, Slovenija, EU
update: sanding and finil finish still missing, for now 2,7 kg. Soon will have chance to test it. (hope she wont drink water due to no top glash layer)


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 Post subject: Re: Strip built core?
PostPosted: Tue Feb 17, 2009 2:26 am 
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Joined: Fri Oct 06, 2006 4:12 am
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Location: Sydney
Ok, that ingraving work is insane. Board looks awsome!


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