Need some help with my deck lay-up

[spleeny92]

So I'm making a board for my senior project. Its going to be 36" long, with a 27" wheelbase, about 1/2" concave, and .75" rocker. I weigh 135 lbs. and want the board to have a slight flex. It's going to be a shorter free-riding board.

I have at my disposal some 1/8th inch Baltic Birch, some 17 oz. Biax. glass at 45*, some 10 oz. uni glass, and if I want to, some 4.5 oz or 9.5 oz uni carbon.

Heres the problem....
I don't know whether to use 2 or 3 pieces of Baltic Birch. I was thinking of one of the following lay-ups.

17 oz. Biax. Glass
1/8" BB
1/8" BB
1/8" BB
10 oz. Uni glass

or

10 oz. Uni Glass
17 oz. Biax Glass
1/8" BB
1/8" BB
Uni carbon (4.5 oz. or 9.5 oz.)

I haven't used carbon, but have used fiberglass many times.
I would like to know if these lay-ups would work and which one would be best
Thanks for your input.

[Hairpin]

So I'm making a board for my senior project. Its going to be 36" long, with a 27" wheelbase, about 1/2" concave, and .75" rocker. I weigh 135 lbs. and want the board to have a slight flex. It's going to be a shorter free-riding board.

I have at my disposal some 1/8th inch Baltic Birch, some 17 oz. Biax. glass at 45*, some 10 oz. uni glass, and if I want to, some 4.5 oz or 9.5 oz uni carbon.

Heres the problem....
I don't know whether to use 2 or 3 pieces of Baltic Birch. I was thinking of one of the following lay-ups.

17 oz. Biax. Glass
1/8" BB
1/8" BB
1/8" BB
10 oz. Uni glass

or

10 oz. Uni Glass
17 oz. Biax Glass
1/8" BB
1/8" BB
Uni carbon (4.5 oz. or 9.5 oz.)

I haven't used carbon, but have used fiberglass many times.
I would like to know if these lay-ups would work and which one would be best
Thanks for your input.

ok, im a junior board builder to. and i have done some fibre glassing, and carbon fibre is essentially the same thing. the layup that i would suggest is

1/8" BB
17 oz. Biax. Glass
1/8" BB
1/8" BB
4.5 oz. uni Carbon

because i made my first board out of 1/8" baltic birch with no glass in it. and it was as flexible as hell. (ie: i could bounce in the middle and make it scrape the ground) so that 17 oz. Biax. Glass and the 4.5 oz. uni Carbon should stiffen it up and the carbon will give it that really nice look.

[spleeny92]

Thanks for the advice.
The 17oz. Biax glass is just there to reduce torsional flex.
I also think I read somewhere that any composites are best used on the outside of the board so I'll probably stick to a wood core and keep the composites on the top and bottom of the board.

Once again thanks for your input.

[cawlin]

fiberglass on the top
fiberglass on the bottom

thats how I do it. I've heard it creates the most possible stiffness with just 2 sheets.

[Hairpin]

Thanks for the advice.
The 17oz. Biax glass is just there to reduce torsional flex.
I also think I read somewhere that any composites are best used on the outside of the board so I'll probably stick to a wood core and keep the composites on the top and bottom of the board.

Once again thanks for your input.

ok. i never knew about that. i was just thinking about how a snowboard works. and it would seem to me that it might be stronger if its on the inside. but its up to you.

[hoch92000]

Wow, I envy your supplies.

Here are a few points/suggestions.

Rocker and flex is not necessarilly a good thing. You want stiffness with rocker, to lock you in and prevent bottoming out. So decide, Do you want rocker or flex, pick one. With rocker, go stiff. With flex, flat with concave or concave and camber is good.

Let's say you want rocker/concave, lke the FSM decks. You should aim for stiffness, so I would include some carbon.

27" WB is on the shorter side for a longboard (but longer than a slalom deck) and with 135# as your weight, it will not take much to get stiffness.

Also, I have experimented with a 1/4" core for a deck, but to be honest, it is really too thin for I-Beam forces to come into play. I think you need at least 5/16". Since you have 1/8" BB, go three plys.

You need some 45/45 fibers and fibers running the length. What is this Biax? Is it 0/90 or 45/45. I would recommend cutting it so fibers are 45/45. Start with one biax on top and one on the bottom. You should endeavor to equalize your skins on top and bottom to prevent warping and optimize the I beam effect.

Now test the flex. If it is your first try with this layup, it is good to start with the minimum and add skins as needed. I bet if you add, one layer of the Carbon uni across the bottom or perhaps a layer of the lighter stuff on both the top and bottom, you'll be good. Keep in mind, this will be quite stiff, but you'll need that with rocker.

[spleeny92]

Thanks for the replies guys.

The Biax is indeed 45/45 so ill use one skin the top and one on the bottom
Also, hoch, what do you mean by I-beam forces. If you could explain this it would be greatly appreciated.

[hoch92000]

I-beam - Wikipedia, the free encyclopedia

[Dimm]

Thanks for the advice.
The 17oz. Biax glass is just there to reduce torsional flex.
I also think I read somewhere that any composites are best used on the outside of the board so I'll probably stick to a wood core and keep the composites on the top and bottom of the board.

Once again thanks for your input.

Yeah make sure you lay down the biaxial so that all the fibers lie diagonally 45/45 otherwise the layup will not reduce torsional flex.

ok. i never knew about that. i was just thinking about how a snowboard works. and it would seem to me that it might be stronger if its on the inside. but its up to you.

Please avoid giving misinformation.