should i have a cross grain or have all the grain going the same way on my board..? to be STIFF
its going to be 9ply thick of 1.2mm birch? for dh/freeride STIFF
there will aslo be a layer of fiberglass on the bottom for more stiff and waterproof
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Replies to This Discussion
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Premium MemberPermalink Reply by Matthys on -
if you dont like tortional flex, you will want to have at least 2, preferably 3 plies running crossgrain.
otherwise it will snap and you wont be able to make any concave...
also
work on your grammer...
that sentence is completely whacked...
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Permalink Reply by Louis Tragear on
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so i have to have atleast 2-3 crossgrain or it will snap or if i have more than 2-3 it will snap..i have mass concave so what would you recommend...thanks man
sorry about the shithouse grammar im lazy
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Permalink Reply by Sakamoto on
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Hi Louis,
this is a really good question, and it's an area of board construction where alot of crew get it wrong.
Longditudinal grain strands are the dictators of stiffness/flex. The best way to make the board as stiff as it posibbly could be, ie, the number of layers/ply, is to run all the veneer's with the grain running the length of the deck. The more veneer's you put into the deck with the grain running across the deck, the more flexible the deck will become. if you are using fibreglass as your bonding agent/medium between the layers, this will also become a determining factor. F/glass, which has a curve in the final product, is stronger than a flat sheet of the same weight/thickness. In this case, the more crossgrain veneer's you put into the deck, regardless of the bonding medium, the weaker the deck will become.
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so if i have all of the grain going down the line of the board with the fiberglass on the bottom it will be rigid but in time torsional flex may become a problem..and im using titebond3 as glue..it has be recommended as extremely stiff, durable and weather proof :)
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Premium MemberPermalink Reply by Matthys on -
without crossgrain plies, i have found that a board literally becomes a noodle
the concave also does not hold, as there is no ridid force holding it there.
10 plies of 1.2mm with 3 crossgrain and a f/glass layer will be plenty stiff...
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Dependant upon the glue/bonding agent you use, torsional flex may become an issue. Concave is another factor in this.
More stable concave, greater stiffness, less torsional flex. Also, paralell lines of the side of the board, which form the edge of the concave, also dictate torsional flex issues. A pointy nosed pintail will have more torsional flex than a straight sided deck.
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Premium MemberPermalink Reply by Steve on -
Most veneer boards have 2 cross grain veneers to aid in the reduction of the dreaded torsional flex. When a board gets to a certain thickness 2 cross grain veneers really aid in the torsional stifness while not really detracting from longitudinal stiffness and strength.
Many. many other factors determine the final stiffness. Concave, hardness of timber used, glue used. fibreglass used, type of fibreglass used, thickness of board, the list goes on and on.....
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i have a tub concave through all of it except the middle/back has a gnarly W
so if i have 2-3 cross grain and maybe 6-8 grain down the board plus the fiberglass it should be stiff and not much torsional flex
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Premium MemberPermalink Reply by Matthys on -
yea, according to my knowledge yes.
use 10 plies though..
usual decks have veneers of about 1.6mm thickness
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Premium MemberPermalink Reply by Steve on -
That should be pretty good and a fine starting point ( only 2 cross grains not 3). Put them 1 or 2 plys in from the top and bottom plys. But not knowing what sort of glass your using, your concave and board shape etc etc, I wouldn't know for sure. You have to give it a go and see for yourself. You get to know your materials after a while and know how they respond. Even experienced builders are in the dark when using totally new materials. Good luck
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thanks guys so pumped...definately use all the advice i've had given to me
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Premium MemberPermalink Reply by sean meaney on -
cant wait to see how your board turns out louis, hopefully you have it done for the kongwak race so i can check it out then, if it turns out how the press looks you gotta build me one
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