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 Post subject: Hi and 2nd board foam core advice
PostPosted: Sat Aug 18, 2012 3:18 pm 
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Joined: Wed Jul 25, 2012 1:40 pm
Posts: 4
Hi to all I,m new to the forum and kiteing so please be kind :D

Ive just finished my first board 60" x 18" twin tip 1/2 ply core with 2x 4oz for base and 2x12oz for the deck vacuum bagging used to apply .the plan had been to not use any cloth on this one but the ply was so poor I had to
ImageImage

Now on to my next board I hope my techniques improve as my kitting does so im not expecting a perfect blend of materials at this stage

I have available to me
materials for vacuum bagging

The only core foam i can get easy/economical is 200gm sq foot which i understand is a bit low on density
I have a roll of 300gm of what i think is e glass about 40 meters so although maybe a little on the heavy side its free

I will be using polyester to start with

has anyone used such a low density foam core if so should i add stringers
and what sort of vacuum should i use to stop the core being a big heavy sponge and absorbing to much resin

Thanks for any advice Andrew

should mention that im in the uk frinton essex


Last edited by andrew bishop on Sat Aug 18, 2012 8:57 pm, edited 1 time in total.

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 Post subject: Re: Hi and 2nd board foam core advice
PostPosted: Sat Aug 18, 2012 4:35 pm 
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Joined: Wed Nov 20, 2002 1:00 am
Posts: 908
Location: rhode island
andrew,
is the core material some form of styrene (EPS or XPS)?
if so, polyester resin will dissolve it. and you'll need to use epoxy the laminating resin.

hard to tell the density of a 200 gm sample until we know the thickness, as well.
but, it does sound like the core strength will be quite low.
8 #/ft3 is a good target for thin laminates like kite-boards

if the core density is much below that the disadvantages will be low compressive strength, and low shear strength .
If its XPS it is also likely to be relatively brittle and begin to fail if over-flexed.

if you choose to use this material i think you should design it as if it were hollow ( and completely disregard any support from the core)

some wood veneer could be used to reinforce compressive loads on the the deck.
reinforced stringers and rails would be needed to carry shear loads.
(if you dont want to make your board very thick)

300 gm/m^2 ( approx 10 oz) doesn't sound too heavy
with the core you've selected, you'll be using alot of it.

have fun.
-bill


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 Post subject: Re: Hi and 2nd board foam core advice
PostPosted: Sat Aug 18, 2012 5:30 pm 
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Joined: Wed Jul 25, 2012 1:40 pm
Posts: 4
Sorry should of said foam is 1/2" Polyurethane Foam Sheets (12mm) at 2lb @ ft 3 so is very low
but at this stage wont be jumping

Thanks Andrew


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 Post subject: Re: Hi and 2nd board foam core advice
PostPosted: Wed Aug 29, 2012 12:45 am 
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Joined: Mon Jan 25, 2010 5:55 am
Posts: 11
I have tried lighter density foams and because the tips get so thin on my boards its hard to work with.
If you can get your hands on some Divinycell you will never go back that stuff is super strong and amazing to work with
but $$$


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 Post subject: Re: Hi and 2nd board foam core advice
PostPosted: Thu Aug 30, 2012 9:25 pm 
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Joined: Tue Aug 21, 2012 2:03 pm
Posts: 6
Andrew, if you want a better core material there is a supplier of Airex in the UK that I have purchased from before, the C70/75 is a good strength and density for kite cores and comes in 12mm thick sheets. I think the only sell full sheets which you will get 3 boards out of. Last time I got some it was about £60 but I've always collected from them so I don't know what shipping costs will be like. Search for a company called Impag


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