cardboard core

[ganipilo]

I do not intend to build a cardoard ski but while searching information about vaccum press on this forum I saw Big Kam's mysterious core thread (before the release of the pallet skis).
I had already saw someone's surf (for waves surfing) made from cardboard so I did a bit of research on this subject. I found this study (http://www.mtm.kuleuven.be/Research/C2/ ... _paper.pdf) wich you might find interesting.

I didn't take the time to read it because I'm supposed to study now but while skimming the study, I tought you might find it interesting.

By the way, don't think it's possible to make skis from cardboard but my english level does not allow me to explain why I'm feeling it's a bad idea. Anyhow, it would be interesting to see someone with a lot of ski building experience to try this out.

[OAC]

Why not? Just think out a good way to construct it. I did a test with foam (not shaving foam ) but it broke. Sort of delaminate, but not in the epoxy, more like "inside" . A millimeter under the surface. I don't have any picture of it, but I will use wood in the future!

[twizzstyle]

Honeycomb is used as a core material all the time in aerospace applications, but it is a nomex-based paper. Normal corrugated cardboard won't be strong enough for a core material in a ski, it will crush when flexed. Nomex MIGHT be strong enough, hard to say without trying - but based on what little work I've done with nomex (have done some) going thin enough for a ski would also make it prone to crushing.

[ganipilo]

Thin... exactly the word that missed in my english vocabulary!

Exactly! Cardboard honeycomb would be too weak in the thinner place of the core. But for cross country ski it would be a good stuff no? Less stress on the skis. Or for skate skiing...

Anyway.

Just tough it may interest you. And maybe restart the garbage core thread.

[Richuk]

Try google translate if you get stuck

[Alex13]

There's no reason you couldn't. GM use cardboard pallets and base supports for transporting engines, I've seen them stacked 6 high (that's around 1700kg of weight on the bottom pallet).

Cardboard is very strong in the right direction. However you'd need vertically laminated corrugated pieces (i.e. one piece of flat cardboard is no good, you need a heap of strips turned on their side).

It might be too thin and just deform though, especially at the tips.

I don't know if normal honeycomb would work, again very strong but perhaps too thin.

[Charles DeMar]

Fischer uses a lot of this technology in their nordic and alpine skis, but the materials are definitely not "cardboard." Volkl's aircore snowboards used "wood pulp" material in the corrugated/honeycomb sections. The aircore boards from the early '00s rode really well, but didn't always stand the test of time...

http://snowboarding.transworld.net/1000 ... l-aircore/

[agiocochook]

There was Hexcel, back in the 70's. I think they were the first ski company to use honeycomb cores. Hexcel also pioneered swallowtail skis.

[skidesmond]

There was Hexcel, back in the 70's. I think they were the first ski company to use honeycomb cores. Hexcel also pioneered swallowtail skis.

I had a pair of Hexcel skis back in the day. They were aluminum honeycomb. Super light. But if memory serves me right, I think they lost their camber rather quickly. Wish I still had them so I could cut them open to see if there was any wood in them and other material.

Using todays modern designs I could see the aluminum honeycomb making a come back for the back country skiers who want the light weight ski for hiking.

[agiocochook]

After Hexcel stopped making skis, I remember a period when a pair was a prize find for back-country skiers. They certainly had lightness going for them, but, in my own experience at least, wood cores just last longer, ski better, than anything else.

[agiocochook]

BTW, you can still buy honeycomb core material from Hexcel ( http://www.hexcel.com/Products/Core+Materials/ ). Looks like they'll profile/shape it for you too...

[doughboyshredder]

http://www.hexcel.com/NR/rdonlyres/599A ... erties.pdf

very informative pdf from that site.

I would sure like to build a core with polyurethane (surprise to me, I had no idea there was such a thing) honeycomb tip and tail sections. Along with a pure cf construction I expect it would be insanely light and damp.

[skidesmond]

Yeah they were light. I remember taking them on a trek to Tuckermans Ravine.... (way back when). Light and easy to swing them around in tight spots. Maybe it's time for a come back. With all the other modern day materials available, could probably come up w/ a decent light weight ski/board. I'll have to check out the Hexcel website.

But I do agree about the durability of wood cores.

[agiocochook]

Honeycomb tip/tails is an interesting idea....and I can definitely attest to the value of light skis for Tuckerman's (not ever having them....). Was able to drive up two weeks ago and ski the Great Gulf area -- very nice.

[agiocochook]

Is anyone familiar with a method of making cores where you start by laying up veneers of your core wood(s) to make a sheet of "plywood" (2'x6'x2", for example)? You then slice core sections off the long edge of the sheet, typically three per ski, and lay them flat so that the grain of the veneers is now vertical. I got two sheets from Olin long ago where one is just wood (3/16" veneers of softwood, sitka spruce I think, alternating with 1/16" veneers of a hardwood), and the other has an extra single top layer of sidewall material. So, when you cut your sections, one comes from the all wood sheet and two from the sheet with sidewall material. Before laminating the three sections, though, you first tack the sidewall sections to the center (wood only) section with the sidewall material on the inside. Cut your shape on the outside wood edges, break the core into three sections again, flip the SW sections over so the SW material is on the outside and when you press the three sections together during lamination, the sidecut cuts (now on the inside) will collapse, mirroring the curve on the outside with the SW material already attached.