Core material too stiff.

[Huck Pitueee]

I just layed up my first "real" snowboard and it seems the core wouldn't hold the rocker through the middle of the board. It just went flat when removed from the form. The core was verticle grain fir and Saligna eucalyptus. Should I look into high density foam as material that will hold its shape? I'm split boarding so a lighter board would be better. And a foam core might hold up ok for back country. Are there suppliers who sell partial sheets?

[MontuckyMadman]

we need more details on your layup.
Core dims?
Composite type and weight?
Resin system?
Heat? NO Heat?
Pressure, vacuum? pneumatic? Pressure in PSI?

[Huck Pitueee]

Core 10mm thick
18 oz e glass top
19 oz biax bottom
Fiberglass hawaii aluzine slow
plenty heat
vacuum no gages but good vac.
Seems like i asked too much of the layup to hold the shape.
Thanks

[MontuckyMadman]

interesting. I think the composite is not strong enough to hold a mild rocker perhaps.
Those are pretty light composites if I understand and a thick core.

[chrismp]

so this is a splitboard? don't known about core thickness for these, but 10mm still seems like a lot.
usually a stiff board has a core around 7-8mm.
and vacuum pressing without any heat might be part of the problem as well.

[Huck Pitueee]

That board is ready fo testing in a few days. Any input on the foam core Idea? I understand foam isn't ideal for longevity but light is right sometimes. We have tons of snow in the Sierras and I would be stoked to test a board with the right rocker. Is Divinicell the stuff to look for? Does anyone sell it in core sized pieces?

[twizzstyle]

What was the orientation of the composite fibers top and bottom? Is the e-glass biax? Was the bottom layer at 45 deg? If the layers were oriented differently that could be one driver of your camber gain (I say gain because you went from negative camber to basically zero camber).

Not many people have had luck with foam cores around here, but you might look at end-grain balsa. A few people have had great results with that.

[Huck Pitueee]

Bottom orientation 45 deg. Top 90 deg. I forgot about end grain balsa what a concept. That stuff must drink resin.

[Huck Pitueee]

It seems like when the board bends into the form the top layers are being compressed and the bottom layers streched. Maybe a pretensioned and cured layer on top will help. Along with a thinner core.

[twizzstyle]

Are you saying you only have fibers running laterally (90deg) on the top? Nothing going lengthwise? If that is the case then that is your culprit. The composite layers shrink when cooling, in the direction of the fibers. If there are no fibers running lengthwise on top, the bottom layers will pull more than the top and cause this camber change.

[OnDeck]

Are you saying you only have fibers running laterally (90deg) on the top? Nothing going lengthwise? If that is the case then that is your culprit. The composite layers shrink when cooling, in the direction of the fibers. If there are no fibers running lengthwise on top, the bottom layers will pull more than the top and cause this camber change.

You spoke my mind. I imagine combining that effect with that thick core would only make it harder to get the profile needed.

Related note, If i ever use carbon stringers i find it quite dificult to predict the effect on vert profile. The carbon resists the tendency for the glass to shrink.

[Huck Pitueee]

One half of the fibers run lengthwise the other half run across the board. Just plain ond eglass. Sad note. I just got back from the local ski shop where they murdered my board while doing a base grind. The split board hardware made the board hang up in the machine. So there is a deep grind mark in the bottom. Almost through the ptex.