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Will it be strong enough

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RichR2
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Will it be strong enough

Postby RichR2 » Sat Jun 30, 2018 1:50 pm

I’m planning my next two builds; a 125 x 48 x 3 pocket board and a 150 x 50 hoover style board but I can’t decide on the lay up and need some advice.
I think I usually overdo it and end up with a board much heavier than I would like, my last 125 x 48 x 5 came in at 3.8kg. On the plus side, I’ve never had a board break.
So this time I’m thinking of a much lighter layup but am worrying that its too light, what do you think?
From the top it will be:
100g e glass
200g Carbon twill 3k
3mm closed cell foam
100g e glass
EPS core with two full length 3mm ply stringers
100g e glass
200g Carbon twill 3k
100g e glass
Plus extra patches around foil tracks
All input would be much appreciated. Thanks.

tmcfarla
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Re: Will it be strong enough

Postby tmcfarla » Sat Jun 30, 2018 6:42 pm

I don’t have any expertise here, but I did a pocket board (108x40x3), with 2 layers of 200 g carbon weave and two full-length strips of unidirectional carbon on each side (about 8 inches wide). Extra carbon patches by foil attachment. It weighs only 2.6 kg including a full deck pad (and core foam is pretty dense), and has been holding well so far. I feel like that is over-kill, but it is still pretty light. If yours are coming out significantly heavier, might check whether you are getting excess resin out.

If I were doing another, I’d do more unidirectional, and just one layer of carbon weave (with extra carbon by foot and foil placement). I suspect the unidirectional is really what provides strength.

BWD
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Re: Will it be strong enough

Postby BWD » Sat Jun 30, 2018 9:04 pm

If you are gentle, 200gsm carbon cloth is usually reported to be adequate. I’m not so gentle so would do more at least around standing area. Extra patches around foil mount on bottom are a good idea. Also worth considering to feather in a strip of the 3mm foam from back to front foot position on the bottom for toughness/stiffness/strength. Uni gives great stiffness and overall strength but vulnerable to point loads like at the front edge of foil plate unless on top of something tougher than light core foam...

RichR2
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Re: Will it be strong enough

Postby RichR2 » Sun Jul 01, 2018 7:40 am

The previous build used 200g glass in place of the 100g and also included a layer of 100g ud top and bottom. Probably resin rich as I wasn't able to vacuum but will with these builds. Still not sure what to go with. Perhaps I should ask what layups have you done that have failed.

revhed
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Re: Will it be strong enough

Postby revhed » Sun Jul 01, 2018 8:03 am

My current DIY board 125 x 50 x 4 uses a rigid and stiff extruded cheap foam core with 300 g/m2 and uni on rails for easy shaping forming.
Did use 1000 g m/2 quadri rektangles about 15 cm x 30 cm top and bottom at STRUT board plate connection for added moment of inertia strength.
Is 2.2 kilos and works great, was vac sacked at about .75 bar and LOTS of time spend roughing foam surface and then micro ballon epoxy applied to ensure cloth adhesion.
Based loosley on Ketos pocket shape and scoop.
Each time now I fly a heavy set up it feels so slow!
R H

bigcane
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Re: Will it be strong enough

Postby bigcane » Mon Jul 02, 2018 7:09 am

I have built several boards, current one is the best so far. XPS core 140x41x7, 1cm pvc foam under feet and foil, 100gr carbon uni strips on deck between feet, 200gr carbon weave top and bottom with 2 extra patches under foil. Pigmented west system micro sphere resin mix to finish, sand and done. 2.6kg and no cracks so far even after jumping. Vac bag is essential to keep the weight down

RichR2
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Gear: Cabrinha
LF Solo
Gong Strutless
Shinn
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Re: Will it be strong enough

Postby RichR2 » Sun Jul 08, 2018 9:11 am

Thanks for sharing your experience. Clearly I'm going a bit far in my reinforcements compared to the rest of you. So, I will go ahead with my suggested lay up and will post how it goes.


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