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Board construction question

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Created by saltyheaven 1 month ago, 1 Apr 2019
saltyheaven
TAS, 498 posts
1 Apr 2019 7:14PM
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Hiya all,

Bit of a question about increasing the long term dent resistance of the deck of a board, eps core. Actually in this case a surfboard, but I'm asking here because I'm pretty sure I'll get a more useful and balanced reply.

The usual way for an eps surfboard is to simply laminate a single glass skin.

I've done the whole bagged sandwich skin before and there's no doubt it works. What I'm looking for is a relatively simple way to achieve a similar thing just for the back half of a surfboard deck. Something that is compatible with a simple hand layup, could be something like coremat but without such a weight penalty, maybe it's even the usual divinycell with some clever trick to get it to stay put sans vacuum.

Thoughts, ideas, experiences?

Or do I just bite the bullet and buy a vac pump?

Imax1
VIC, 1870 posts
1 Apr 2019 7:45PM
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I'm presuming laying up a sandwich will be strong but heavy . You could roll a layer of resin and tape a core down , then lay up a layer of glass and then fill . I've done this , indestructible but Heavy .
Whats wrong with just laying up a layer of 6 oz ?

saltyheaven
TAS, 498 posts
1 Apr 2019 8:32PM
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Thanks for the reply Imax.

I don't think a sandwich is too much weight penalty, it's just a frig around and I don't currently own a vac pump.

Have you had success taping a 3mm core down? I'm guessing pretty heavy on the resin underneath to alleviate voids and hence the weight...?

What's wrong with just laying up 6oz? That's what I've been doing for ages, actually 2 x 6oz plus a patch under my back foot so 3 x 6oz in that area, this is over 27kg/m3 EPS. The problem is the core sinks slowly but surely over time, significantly too. It's probably the thing that spells the end for the board before anything else so I'm keen to solve the sinkage.


Cheers!

saltyheaven
TAS, 498 posts
1 Apr 2019 8:57PM
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Here's an idea off Swaylocks from Bert Berger.... Sounds plausible to me.


also wells if you can support your rocker ..like if you have a sand pit nearby....
you could use divinycell without vacumn......

get a sheet of plastic and bed your board into the sand , so its supported evenly under the whole board, (or at least where you want to put divinycell)..
then glass the back of a sheet of divinycell ,place on your foam blank , where youve shaped it to fit , then lay a sheet of plastic over it and cover it with sand ....it gives a real even pressure and is quite heavy.....
thats how we do repairs on small jobs where it doesnt warrant using the pump....but i once had to do a whole deck that way in an emergency....

the motor on our vac pump burnt out while it was in use....
our glassing area had a sand floor , so i moved a few glassing stands and it became a temporary sandwich application area....
a couple of customers came in , looking real confused why we were burying a half made board in our glassing bay,,, you had to be there....

decrepit
WA, 9115 posts
1 Apr 2019 6:07PM
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yep that would work. The other alternative is to use a carbon patch instead of glass, it's much stiffer and dent resistant, but a 3mm sandwich would be better.

saltyheaven
TAS, 498 posts
1 Apr 2019 9:25PM
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Thanks Decrepit. The more I think about it the less I'm interested in a half way solution. 3mm sandwich coming up! Think I'll do some experiments with sand and see if I can get a rail wrap to sit down tight.

decrepit
WA, 9115 posts
1 Apr 2019 8:06PM
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depends how far round the rail you want to go, it's going to be hard with sand sitting on top, to get any tuck pressed in.

If you're making the board from scratch, I've just used d-cell on the impact area.

Mark _australia
WA, 19102 posts
1 Apr 2019 8:11PM
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you won't get far around the rail with sand pressure.....

If its just strength and heel dent resistance why not wood?

It 500kg/m3 and unidirectional. Half a surfboard is around 100g for 0.6mm pine.

Carbon patch under heel if you want to add more?

But again needs to be vac bagged.

R1DER
WA, 1205 posts
1 Apr 2019 10:53PM
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Bert already gave you the answer.
He doesnt wrap the rail due to having solid balsa rails.
Dont wrap the pvc, sand and feather it in to the top of the rail then glass over.
When I had a power cut doing a deck on a 42c day I used packing tape super stretched tight with the sand method.

saltyheaven
TAS, 498 posts
2 Apr 2019 9:23AM
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Thanks guys, All super useful input. Lots to consider and experiment with.

Especially the reminder from R1DER about solid rails, makes such good sense from a finished product and ease of construction sense. That feels like a likely direction for me.

So, I might look around for an affordable but not too crappy vac that will do the job, any suggestions for what's currently available? I'm a keen and long term backyard board builder so it'd never see anything even remotely approaching production use, once a month at most, probably far less most of the time.

515
170 posts
2 Apr 2019 9:19AM
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You know if you have vacuum you will always use it.

Balsa rails - wow!
What's your plan to glue the balsa rail on?
Shape board cut rails off, glass deck on rocker jig. The glue balsa on shape rail.
So many different ways to build a board



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