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 Post subject: how low can you go ??
PostPosted: Thu Jun 20, 2013 2:26 pm 
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Joined: Fri Apr 06, 2012 2:01 pm
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simple question, lot's of issues !

trying to built some light weight wood boards, how low can you go ?

first one : 152x50, 8 kg
second : 148x49 , 4,5 kg
third, deck only before sanding and glassing : 2.15 kg, 140x45, i cant get lower with the wood, it' already 2 times baltic 3 mm plys, hollowed inside 1,5mm for both in a fish bone patern.

any tricks ?

dont say use foam !!


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 2:43 pm 
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You could use okoume ply, or a wood strip core of paulownia, cedar, or balsa, balsa would be lightest, obviously.
2.6-2.8kg complete s not too hard. Little details like how much epoxy or plastic in rails, how thick top resin coat, etc add up...
Be careful subtracting too much wood from 3mm birch - it has only 3 plies to start, right?


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 2:53 pm 
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yep, 3 plys ! substracted one and a half ply !

ok, anyways, that's a board made to try the shape before making one from foam and carbon ( just received my carbon/basalt cloth ! )

no rails ( going to wrap them ) one set of inserts, one payer glass only top and botom, hand layed and vac baged to wrap, finishing coat only on the bottom as i'm going to glue a layer of foam carpet on top ( the bright plastic foam pads that u can use in childs room ! ) to ride it strapless, get down on production price ( just have to buy straps, no pads, and, ads floats and color for retrieving the board.) .

hope to stay under 3 kg without straps.

okoume is cool, but, 68 dollars the 4 by 8 sheet ( one board ) where the baltic birch 5 by 5 sheet will be 12 dollars. ( one board ), and okoume is only 1/4 inch so, to make a glued shape, you dont get that mutch down on weight !


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 3:09 pm 
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Joined: Tue Feb 24, 2009 1:43 pm
Posts: 306
Location: Iv.G.-Slovenia
Hi!

I just finished a composit Alaia 165 X 42 cm, no rail, no inserts, taper from 7 to 14 mm. Finished with PA topsheets. I used plys which are a combination of 2 x 1 mm Paulownia vener and 1 x 1,5 Balsa. So the board's taper is from 2 to 4 layers of ply, middle 2 layers have cuts to reduce weight. The weight is under 3 kgs. :thumb:
I didn't get so good resaults with Oukume plys on 140 x 43 TTs. The weight was a bit higher, but it was to much stiff.

Go simple, don't use the whole catalogue of materials!


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 3:15 pm 
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i shurely would like to get my hands on that plywood !! i could get down to a one kg deck before glass ! wow ! where do you get it ?, please, tell me it's in montreal !!


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 3:32 pm 
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Zob that ply sounds cool!
Like to know details about it, although I'm in us so it might be hard to get here.
It would be cool to see some more pictures of your boards,too, if you want to show them...


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 6:31 pm 
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Location: Iv.G.-Slovenia
It is no secret. Like I said, it is a 3 layer ply. 3,5 mm thick. Top layers are 1 mm thick Paulownia, the grain runs longitudinal, the midle layer is 1,5 mm thick Balsa and the grain perpendicular to lenght of the sheet. Dimentiones are approx. 2420 x 1220 mm.
I would also like to find a supplier, because where I buy it, I have to go through hundreds of plates, to find 3 or 4 I could use. I prefer this Pau-Bals combination over Okoume. It is much lighter and flexier and easier to work with.

I already presented some of my boards here. I still make a lot of progress with each new board I make, so this tells me I am stil far from perfect. Curently my biggest strugles are pouring the epoxy rail without having to correct it 2 or 3 times to get the whole rail (I prepress the core, than pour the rail, than apply the top shets). The other strugle is how to get finished surface without air traped beneath the top sheet or precured glass.

I shot 360 GB of pictures for Timelapse of building/modifying the rocker table for new composit wood Alaia and building the board. However, now when I am finished with the board, I have to make a video of my snowkiting vacation in Erciyes in Marh/April :D, than I will start on these Timelapses.

Some recent boards:
Alaia
LW TT
Wake skate


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 7:12 pm 
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Those boards look nice!
But can you say the name of the mill or brand of that plywood?
It might help to find it, or a similar product, in other countries....
Look forward to the videos,
nice cars by the way.


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 7:21 pm 
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Joined: Wed Nov 20, 2002 1:00 am
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Location: rhode island
thats sounds a lot like a trick question.

comparable to light weight fat people.

no foam cores?
how about hollow cores?

the one advantage wood has over other core materials is its tensile strength.
the obvious disadvantage in most case is its weight.
generally, cores dont need a lot of tensile strenght just a moderate amount of shear strengh.

composite skins using wood can develop alot of tensile strength while enhancing resistance to buckling (flexural stability)

balsa rails or cheap stringer or cheap FOAM can provide the required shear strength.

consider laminate of: 4 oz glass /2-3 mm balsa core / 4 oz glass.
use the above laminate as skin on top and bottom of your chosen core.
core could be balsa stringer or balsa rails along with .5lb home depot EPS.

core thickness will be function of tensile capacity of your skins.
core density will be a function of the thickness of your skins.

final weight will be a function of both.
after that its just math

you mix and match until you like the answer.
if you dont ever like the answer, folks move on to carbon and nomex

weight of glass: 4oz /yd^2
weight of epoxy: glass x 2
weight of balsa: 6-8 l/ft3
weight of EPS: .5-2 lbs/ft^3
weight of okoume: maybe 40 lb/ft3

make sense?


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 Post subject: Re: how low can you go ??
PostPosted: Thu Jun 20, 2013 8:22 pm 
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Location: The Naki
carbon !


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