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How bad is Biax?

 
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Mista Sparkle



Joined: 01 Jan 2015
Posts: 5

PostPosted: Sat Apr 16, 2016 6:00 am    Post subject: How bad is Biax? Reply with quote

I got a hundred yards or so of biax glass ~4-8" wide for free, so I'm wondering how much worse it tends to behave than triax?

I'm in the process of building a pair of big mountain skis, not decided on dimensions yet but something moderately wide... I have a yard of triax left over that I figure that i could mix in, but not enough to do the whole pair.

Has anyone done a side by side comparison of the 2 types of glass in an equivalent layup?
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MontuckyMadman



Joined: 20 Jun 2008
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PostPosted: Sat Apr 16, 2016 11:23 am    Post subject: Reply with quote

What weight biax is it?
U have to have synth n on the 0 axis.
skis bend that way.
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vinman



Joined: 09 Nov 2007
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PostPosted: Sat Apr 16, 2016 3:49 pm    Post subject: Reply with quote

biax only in an adult ski would be way too soft, there is no fiber in the longitudinal axis.

If you do biax only you'd need to add some unidirectional carbon or fiberglass to give it some strength in the 0 axis.

I have used biax only when I build very small skis for my kids and even then I add some carbon tow longitudinally.
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gav wa



Joined: 18 Feb 2014
Posts: 325
Location: Perth

PostPosted: Sun Apr 17, 2016 7:52 am    Post subject: Reply with quote

If it is biax with 0' / 90' fibre orientation then its usually pretty handy. A lot of board manufacturers are using it with mixes of carbon or even triax on top, biax on bottom. Takes a bit of testing to get it 100% sorted but can be used to make a really light weight board without losing flex.
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Akiwi



Joined: 15 Jan 2015
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Location: Olching (Near Munich) Germany

PostPosted: Sun Apr 17, 2016 10:31 pm    Post subject: Reply with quote

As an addition to what has already been said, you need to understand what the various strand directions are doing in your ski or board build.

The strands running lengthways are there to add stiffness and strength when a ski is being bent straight up or down. The strands running at 45 degrees (Probably the biax cloth you have) are mainly there to help increase the tortional rigidity or twist of your skis.

I combine biax and uni directional fiberglass when making longboards so you could easily do the same.
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Mista Sparkle



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PostPosted: Mon Apr 18, 2016 7:15 pm    Post subject: Reply with quote

It's actually a plain weave, probably in the range of 8 OZ glass. If nothing else, I imagine it would be nice and clear...

It's ~.011" thick~16tpi something maybe like this the 7-1/2Oz fabris(Part # - 243, 244) at fiberglast . I figure it should be reasonably comparable if I build it to an equivalent weight so ~3 layers... I could thin the core up a just a touch to reduce its stiffness along the ski and the slight excess of glass may be able to make up for a slight loss in torsional rigidity... Gotta work a bit more on my calculator...

I'd post some photos but It looks like I need a few more posts.

-Mista
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Mista Sparkle



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PostPosted: Mon Apr 18, 2016 7:16 pm    Post subject: Reply with quote

I also got a bunch of carbon tow from a guy at work, but I think it's probably about useless...
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MontuckyMadman



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PostPosted: Mon Apr 18, 2016 9:34 pm    Post subject: Reply with quote

You coild orient the plain weave on the bias and use the tow on the 0. Woild be like triaxial 45/45 0.
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vinman



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PostPosted: Tue Apr 19, 2016 3:11 am    Post subject: Reply with quote

What weight is the carbon tow? I usually use 12k tow. 4-8 of these in the 0 axis top and bottom definitely stiffens things some.
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Mista Sparkle



Joined: 01 Jan 2015
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PostPosted: Tue Apr 19, 2016 5:07 pm    Post subject: Reply with quote

MontuckyMadman wrote:
You coild orient the plain weave on the bias and use the tow on the 0. Woild be like triaxial 45/45 0.


Hmm, Well, it's too narrow to lay at an angle for any reasonable length...
What I suppose I could do is use a couple layers and heavily skew the fabric so one layer would act as -45/0 and the next would act as 0/45... This seems reasonable. Maybe even if it's light enough for 3 layers, it would end up being -45,0,0,45,0,90. does that seem like excessive 0?

Not sure on the weight of the tow, I'll look into that.
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vinman



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PostPosted: Tue Apr 19, 2016 6:19 pm    Post subject: Reply with quote

or you could just buy some 22oz triax from Jamestown distributors...free shipping on orders over $50 until the end of the day tomorrow
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Mista Sparkle



Joined: 01 Jan 2015
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PostPosted: Tue Apr 19, 2016 6:31 pm    Post subject: Reply with quote

vinman wrote:
or you could just buy some 22oz triax from Jamestown distributors...free shipping on orders over $50 until the end of the day tomorrow


Yeah, but where's the fun in that....
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MontuckyMadman



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PostPosted: Tue Apr 19, 2016 6:39 pm    Post subject: Reply with quote

Or buy some 45/45 biax (double bias) and use that on the 0/90 orientation...
Or lay up the tow on a 45/45 woven with fiberglas tape and use that 0/90 or do a backflip.
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twizzstyle



Joined: 07 Mar 2006
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PostPosted: Fri Apr 22, 2016 7:03 pm    Post subject: Reply with quote

Just remember that any fibers running 90 (laterally on the ski) are doing nothing for you but add weight.
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Akiwi



Joined: 15 Jan 2015
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Location: Olching (Near Munich) Germany

PostPosted: Sun Apr 24, 2016 10:38 pm    Post subject: Reply with quote

Or as said, buy some Unidirectional fiberglass and combine it..
Or go exotic and add some Carbon Unidirectional.

I bought some Carbon Unidirectioal matting, and because it is so expensive I cut it into about 1 cm strips and add it where I want some extra stiffness in the skis. Means you don't have any waste.
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