difference between telemark and alpine skis?

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littleKam
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Post by littleKam »

no i haven't had a chance to get my hands on some carbon to experiment with but i hope to make an all carbon ski in the future. i'm pretty much clueless about the stuff though and have no idea as to how i would even use it let alone make a core from it. where do you get your carbon from and what is the core construction process like?

if the carbon and wood do have tendencies to separate could you laminate some sort of super thin rubber layer between the two to prevent delams?
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pbelitz
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Post by pbelitz »

What you (I?) should do is use balsa as a filler material. As far as I can tell, the DB/Goode construction process uses foam as a filler, and wraps carbon around several foam stringers. Then the carbon-wrapped foam pieces are epoxied together, and more carbon is overlaid the entire thing.

Would be absurdly light. But it would make for one hell of a production process.....
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endre
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Post by endre »

Sounds like a of mechanical bonding to the core. I guess that is a bombproof way to avoid delams. (but not breaking) It will be interesting to see what db does now, when they don't cooperate with goode anymore. I talked to Cyrille last summer, he mentioned they were testing with magnesium inlays. Obviously wheight is their niche. They should use honycomb while at it!

My core was made from horizontally laminated ash. 3axial carbonfibre on top and bottom just like normal glassfibre layup. Where I come from there is a producer of cf mats (for windmill wings) and I get it from them.

I have heard a rumor about cf prices being doubled last month because boeing and airbus have started production of carbonfibre airplanes and vacuumed the marked. Not shure if that is true, but if it does it means very cheap cf in a few years. :)
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Post by Carbo »

I haven't heard anything about wood/carbon delam issues, but it could make sense in my head. I don't think rubber would help, just prep the surface better. End-grain balsa sheets would probably be the easiest thing to make a carbon ski from first. With the stiffness of a carbon laminate I wouldn't think you would need any added stiffness from the core, you just want a space filler. Unless you're damn sure of your foam that's not the route I would take. There are just SO many types of foam out there I would be bummed to pick the wrong one.

As for db: Looking at the sketches and thinking it through, I *think* db might make their cores exactly like a wood core. They take sheets of foam and make a sandwich with thin carbon layers. Then they stack up the sheets (just like stacking up your wood layers), turn them on their side and mill the ski sidecut cut shape and height profile in them. Think of the carbon/foam vertical layers more like poplar/maple layers, I'll bet the cores are made in the same way.
Then they drop the vertically laminated core in the press and proceed as normal.
If you're making large quantities of 4'x8' carbon/foam sandwich sheets it doesn't add too much more time than milling a standard vertically laminated wood core.

of course this is conjecture......

as for the price of carbon, yes it has gone up, about 15% in the last 8 months or so for us. Demand is outrageous, a lot of this is to do with jet production, but also because Dubya is making a lot of composite armor panels and helmets for the army. And of course the price of delivering it has gone up with the price of gas. My company is putting in orders for 2007 now so we can guarantee delivery, not normal.
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bigKam
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Post by bigKam »

question: what exactly is the cause of the delam? any thoughts out there? i'm curious.
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endre
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Post by endre »

there has been a discussion concerning exactly this at graf forum (i'v joined it as hals) recently. - design and shaping -carbon in the core
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