Oak ?

[alexisg1]

Hello everyone, long time no see...

I wanted to know if anyone has ever tried to put some oak strips in its woodcore ?

I made some skis with a core made of strips of pine and ash. But now that I do not have access to woodworking machinery anymore, I am planning on buying the strips from a DIY shop...And the only strips I can find are pine and oak.

I've found oak is :
- modulus of elasticity : 1200 kg/mm²
- modulus of rupture : 10 kg/mm²
- density : 0.7 g/cm3

A bit heavy but should replace ash not too bad...what you think ?

[twizzstyle]

I put two oak stringers in one pair of my piggy sticks, and two maple stringers in the second pair of piggy sticks I made (most of the core in both pairs is spruce). I haven't skied the maple ones yet, but the ones with oak feel great. The cores with maple felt about the same as the ones with oak before layup so I imagine they'll ski the same.

[AKGeoSkier]

I've put two oak stringers into a maple core, and it seemed a touch stiffer. Definitely make a really good looking clear topsheet though with the stark differenc ein wood appearance, and I imagine the screw retention is better between oak and maple.

[shopvac]

I used a pallet to build cores for the pair of skis I ski on now and it has some oak in them (also cherry and poplar I think). The oak is heavy but if you use another lighter wood with it the cores will be fine. I like the way my skis perform.

[alexisg1]

OK, thanks for the answers !

I hope it won't make my cores too heavy...as i am planning on trying to make light skis (for touring).

@AKGeoSkier : therefore I am gonna use carbon fiber...I'll work on the esthetic the next time

[AKGeoSkier]

Ive been playing around with using 9oz biax glass and 3 inch uniaxial 6 oz carbon tape on bottom only. Makes a really light ski, definitely feels different though. Since the top doesnt have the 0 degree reinforcement, it tends to feel less snappy, but for a light touring ski, it has worked great so far. I truly think that a very light ski could be made using a layup as follows:

base/edges
VDS
3 inch uniaxial carbon fiber 6 oz12k
6 oz biax carbon fiber 6k
core
6 oz biax carbon fiber 6k
vds rubber?
thin layer of aluminium, something like 7075 or other fairly brittle alloy.
no topsheet.

the aluminum is way stronger than glass in compression and the CF would be great in tension, best of both worlds. Definitely couldnt do it in a heated press though, due to the nonsymetric layup.

[alexisg1]

snappy ?

My lastest and only skis hade +-45°FB and 0/90° CFK on top and bottom (don't remember the weight though ), and they are just incredible.
However CFK is not easy to make bond and pretty expensive, therefore i'll go for more carbon, no aramid (or kevlar) and lighter core.

thanks, alex

[shopvac]

What is CFK? Why is it hard to bond and how is it different than carbon fiber? Thanks.

[alexisg1]

It is Carbon Fiber Kevlar I guess.

Kevlar is the brandname for Aramid , and I've heard somme people say on this forum that it is harder to make it bond, as it's harder to wet the aramid fibers.
I must say that I've had some problems with my pair of skis, but I can't really say if aramid is at issue, or if it's the quantity of resin (not much in my pair) ar the molds that did not behave well on the area of tip & tail.


oups...I just googled CFK and it seems to be only classical carbon fiber...

[doughboyshredder]

Bonding Kevlar is different than bonding glass or carbon. With glass and carbon the epoxy actually impregnates the fibers. Epoxy does not impregnate kevlar fiber. So, the bond is actually created by the epoxy surrounding the fibers. It is very important when using kevlar to ensure that you saturate the piece of fabric as much as possible, while keeping in mind that you need to work the epoxy around the fibers, and not in to the fibers.

[twizzstyle]

I hate kevlar... back in school (aeronautical engineering) we built a 10ft long UAV that the entire fuselage and wings were kevlar. That stuff is such a pain to work with, hard to cut before layup, hard to cut after layup. Carbon is a dream, way easier to work with. Kevlar is just good for durability, and damage resistance, but in a ski/snowboard I'd just stick with carbon.