Biaxial Flax as Composite

[Danielbroski]

After building a few successful pairs and getting a solid process down I have been wanting to do some experimenting with natural composites. From some research I found that flax or hemp could be suitable. options. I couldn't find any hemp that was heavy enough or woven in a bi or triaxial, but I did find a biaxial +/- 45 degree flax material.

http://www.easycomposites.co.uk/product ... 49bac2997b

It seems like it will be plenty stiff and I have read it has great dampening properties, but I'm only worried it will be too thick in the ski. On a data sheet I got from the distributor it says that before compression it is 1.8mm, and after it is 1mm to 1.2mm thick. It seemed to me like this is pretty darn thick. What do you guys think?

I also know that Faction uses flax in some of their cores, I am assuming they vertically laminate it in the wood.

[MontuckyMadman]

Sounds thick.
Pretty sure faction candid is the bcomp cores with balsa and flax vert lammed like you said.

[OAC]

I took a turn into the flax road, this summer, and made a pair with it. Mostly because I've heard alot of it especially here on the forum. Honestly, I was/am really disappointed about the outcome.
I used the biax in one layer under and above the core combined with a uni FG.
First, it consumed way too much resin and difficult to work with.
Second, therefore the composite layer became way too thick
Third, First+Second=too heavy ski!

I don't know about the other guys experience, but I don't think it's 100% optimal to use it in skis.

:-)

[pmg]

Hi OAC,

how did that ski ride?

[Idris]

Hi Danielrahn

I regularily make skis from flax - I use the biax and uni together to replace triax glass.

I use it to replace 750gsm glass - If I keep the same core I put the Uni next to the core and the biax next to both the base and topsheet. If I reverse this I need to make a thinner core as the flax is sitffer than the glass, the maths are beyond me so I asked the nice guys at Bcomp.

As for weight, yes a bit more, but like 50gms or so if I do the straight swap, if I go down the thinner core route I get about the same as glass.

Yes as OAC said it does absorb a lot more resin and is a pain to work with. I think my results are differnt as I am using a Pneumatic press rather than vacuum - 45psi in a 9" hose, that works out to be 13-17 tonnes depending on ski lenght!

Skiing they have the same flex as the glass equivalent but are more damp (less rattly on hard) but do have slightly less pop, but dosen't matter in a freeride ski.

[pmg]

Hmm, the last builds I did were with carbon - very poppy. And I like it this way. But maybe the combination of carbon and flax could be quite nice - Afaik thats what they usually do.

[Danielbroski]

Idris,
How much thicker would you say the flax composites are than a glass composite after it is pressed?

[OAC]

Hi OAC,

how did that ski ride?

I don't know... They won't appear in the snow. If you know what I mean..
I will continue to work and experimenting with regular composites. It's enough of parameters there, for me, to play with.
You shouldn't hesitate to try and test. This is just my experience.

[SleepingAwake]

I build a pair last year using the biax fabric from bcomp (350gsm) in combination with uni glass. I'm super stoked about how they perform.


here some pics: http://www.skibuilders.com/phpBB2/viewtopic.php?t=4614

give it a try!

cheers, Reto

[skidesmond]

I made a flax/CF all mtn ski last season. I used uni-CF 9oz weight 3inch wide strip which was far too much CF. A 4-5 oz would have been better or perhaps a 1 inch strip of 9oz. The ski was stiff but it ripped like hell!

I agree with the other comments. It can be difficult to cut, very fibrous. It does take more resin to wet out and it is thicker.

You best bet is to make up some sample layups of flax/FG or flax/CF combinations and start measuring,flexing, twisting etc against a baseline layup to get a feel for it.

One positive note in a flax/CF layup is there is no itchy FG to deal with.

[Idris]

Idris,
How much thicker would you say the flax composites are than a glass composite after it is pressed?

Side by side comparison, same ski, one glass one flax



Why are people mixing flax with FG or CF? why not keep things pure Biax Flax + uni Flax

[Dtrain]

weight savings. If you use that bc comp biax uni Combo in a huuuuuge width powder ski, it would weigh 7 pounds. Plus there would be too much torsional rigidity with a good core. Great for a carving ski, but I think they should lower the gsm of that biax to make it more useable all round.

[Dtrain]

I will admit a guy could play with his core thickness to achieve a desires flex as this stuff specs out pretty strong, but at the flax prices that could get expensive

[Idris]

I will admit a guy could play with his core thickness to achieve a desires flex as this stuff specs out pretty strong, but at the flax prices that could get expensive

I just figured out why the differnce in experience over weight etc.... - different flax supplier - this http://www.bcomp.ch/54-0-flax-fibre-fabrics.html is what I've been using - far finer and lighter material, guessing different strenght/stiffenss specs (per gsm) also.

Yes costs me more than FG but still cheaper than CF - and for the same stiffness ski, same weight as FG and more damp.

[Dtrain]

And I love your look. No glass here either. Made the jump right at start to basalt, won't go back. We've done some full stitched triax carbon too and it's absolutely amazing the snap and weight of the stuff being produced.