I just noticed that son of sinecure's (tgr) skis were built by 333 with 12oz bias glass. For a resort skier is this even safe? Am I overreacting to think that skiing these as a resort ski is dangerous?
I know for touring skis people are going that light, but for ripping bumps and jumps, etc???
lightest glass that is safe to build with?
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doughboyshredder
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LifeisRiding
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doughboyshredder
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I been working on that idea right now. I’m not going as light weight as 333, but I have four pairs of skis that all have lighter glass top and bottom. Here’s what I’ve done so far.
Base/edges
VDS along edges
17 oz biax
Wood core w/ wood side walls on 2 pair, faux cap on 2
20 oz triax on top
8oz. texalium
Silk
2-4 oz glass
My reasoning for putting the 17 oz. on the bottom is that it is on the tension side, which I’m thinking can be a bit lighter. While the 20 oz + 8 oz on top to make the compression layer tougher/stronger. I figured that would take best advantage glass’s strengths. I went with biax on the bottom, because it was what I could find at the time. It came in 6, 12, 24, 50 inch widths. The 20 oz was the same but came in 12.5, 25, and 50 inch widths.
One pair of skis have been out for about a month now to a guy that hosts/guides at a local resort. They are used every day and so far no complaints. He really likes them. He made the core out of maple and did some shaping like a scotty bob profile only. The bob tail is not there and it has the same side cut on each side. Turned out to be a mostly capped ski. The others have yet to be tested, but I know one pair is too soft for me… and almost anyone else.
The next step for me is to make a torsion box with glass or basalt sleeving down the center of the ski with a light biax under the core and a very light, so I can see the wood grain in great detail, layer on top. Something in the 4-6 oz range. The biggest thing holding me back on this idea is the cost. The sleeving is kind of pricey. Not a show stopper , but close.
Got to go more later… maybe
Hafte
Base/edges
VDS along edges
17 oz biax
Wood core w/ wood side walls on 2 pair, faux cap on 2
20 oz triax on top
8oz. texalium
Silk
2-4 oz glass
My reasoning for putting the 17 oz. on the bottom is that it is on the tension side, which I’m thinking can be a bit lighter. While the 20 oz + 8 oz on top to make the compression layer tougher/stronger. I figured that would take best advantage glass’s strengths. I went with biax on the bottom, because it was what I could find at the time. It came in 6, 12, 24, 50 inch widths. The 20 oz was the same but came in 12.5, 25, and 50 inch widths.
One pair of skis have been out for about a month now to a guy that hosts/guides at a local resort. They are used every day and so far no complaints. He really likes them. He made the core out of maple and did some shaping like a scotty bob profile only. The bob tail is not there and it has the same side cut on each side. Turned out to be a mostly capped ski. The others have yet to be tested, but I know one pair is too soft for me… and almost anyone else.
The next step for me is to make a torsion box with glass or basalt sleeving down the center of the ski with a light biax under the core and a very light, so I can see the wood grain in great detail, layer on top. Something in the 4-6 oz range. The biggest thing holding me back on this idea is the cost. The sleeving is kind of pricey. Not a show stopper , but close.
Got to go more later… maybe
Hafte
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doughboyshredder
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that seems like a lot of fiber if you ask me. The texalium, silk, and light glass seem unnecessary imo. Comparatively 333 is building with a total of 24 oz versus the pair you just described with 47 oz of fiber per square meter. That is a huge difference in the amount of fiber put in the ski.
I am curious as to your reasoning behind the top layer needing to be stronger. I gotta think about that one for a bit but I think your reasoning is sound.
I am curious as to your reasoning behind the top layer needing to be stronger. I gotta think about that one for a bit but I think your reasoning is sound.
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LifeisRiding
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doughboyshredder
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The texalium, silk and light glass are not necessary, but neither is a plastic top sheet. 
Only difference is the texalium adds structure to the top side. And I can do without it and did for the first couple of years, but I like the effect and I had a compression fracture on a ski last year that did not have the texalium layer (~60 days of use before the failure). So I figure the extra reinforcement couldn’t hurt.
The composite materials we use in the skis tend to be stronger on the tension side of the flexed ski. I figured that if I wanted to reduce weight the best place to take it from would be the tension side of the composite, so I am reducing the weight of the composite on that side i.e. the layer of glass under the core. Not as much as 333 I prefer to take small steps until I know how the ski will perform and hold up.
I guess it depends on what you are trying to accomplish. It makes sense what LifeisRiding said about doing just the opposite for a snow board for the use intended. But I have nothing to really back that up I don’t remember or have the math skills to calculate actual numbers.
I have noticed that the weight of the ski tends to be related more to the type of core material that I use. My ash boards are ~1 ½ lb heavier than the boards with a poplar core, and the cypress ones are lighter still. As small / thin as the cores are I didn’t think there would be that much of a difference. Skiing them all side by side I really can’t tell the difference in how they perform, at least in the conditions of the day.
Only difference is the texalium adds structure to the top side. And I can do without it and did for the first couple of years, but I like the effect and I had a compression fracture on a ski last year that did not have the texalium layer (~60 days of use before the failure). So I figure the extra reinforcement couldn’t hurt.The composite materials we use in the skis tend to be stronger on the tension side of the flexed ski. I figured that if I wanted to reduce weight the best place to take it from would be the tension side of the composite, so I am reducing the weight of the composite on that side i.e. the layer of glass under the core. Not as much as 333 I prefer to take small steps until I know how the ski will perform and hold up.
I guess it depends on what you are trying to accomplish. It makes sense what LifeisRiding said about doing just the opposite for a snow board for the use intended. But I have nothing to really back that up I don’t remember or have the math skills to calculate actual numbers.
I have noticed that the weight of the ski tends to be related more to the type of core material that I use. My ash boards are ~1 ½ lb heavier than the boards with a poplar core, and the cypress ones are lighter still. As small / thin as the cores are I didn’t think there would be that much of a difference. Skiing them all side by side I really can’t tell the difference in how they perform, at least in the conditions of the day.
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bobbyrobie
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doughboyshredder wrote:examples? Just curious.LifeisRiding wrote:alot of park specific snowboards use triax on the bottom layer and biax on the top to give the board more lateral flex and play. it make tweeked out nose pressing alot easier.
I am also curious of this, what companies are doing it? I was under the assumption most used a biaxial setup.
capita does it: http://www.capitasnowboarding.com/tech (have a look at their fibreglass configs down the page)doughboyshredder wrote:examples? Just curious.LifeisRiding wrote:alot of park specific snowboards use triax on the bottom layer and biax on the top to give the board more lateral flex and play. it make tweeked out nose pressing alot easier.
k2 does it too, but the other way around: http://k2snowboarding.com/boards/parkstar (triax top, biax base for their parkstar)
they tend to put the stronger layer on top for most of their boards, but a couple have the stronger layer on the base.
and there's a couple of other manufacturers that i didnt bother searching
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doughboyshredder
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for K2 is that cause it's a rocker? I have been wondering about this. If you have an extreme rocker or just a continuous rocker aren't the forces exerted on the fibers different? Wouldn't the top fibers be under tension now and the bottom fibers under compression? If so wouldn't a board with camber and rocker be affecting the fibers differently depending on where in the camber / rocker profile they are oriented?chrismp wrote:capita does it: http://www.capitasnowboarding.com/tech (have a look at their fibreglass configs down the page)doughboyshredder wrote:examples? Just curious.LifeisRiding wrote:alot of park specific snowboards use triax on the bottom layer and biax on the top to give the board more lateral flex and play. it make tweeked out nose pressing alot easier.
k2 does it too, but the other way around: http://k2snowboarding.com/boards/parkstar (triax top, biax base for their parkstar)
they tend to put the stronger layer on top for most of their boards, but a couple have the stronger layer on the base.
and there's a couple of other manufacturers that i didnt bother searching
hmm, good question...never thought about it that way.
capita uses biax top and triax base only on one rocker model. all the other with this glass combination are cambered boards.
all their other rockers are just biax (one with only 15oz glass!).
at k2 all the rocker boards either have equally strong top and base glass or a stronger base layer than the top layer.
for their camber boards it's the other way around.
capita uses biax top and triax base only on one rocker model. all the other with this glass combination are cambered boards.
all their other rockers are just biax (one with only 15oz glass!).
at k2 all the rocker boards either have equally strong top and base glass or a stronger base layer than the top layer.
for their camber boards it's the other way around.
In the first skis I made (in 2004) I used a very thick plywood core (4 mm at tip and tail and 16 mm in the middle), and I used 400 g/m2 UD plus 300g/m2 biax glass below the core and nothing above the core (or only biax above the core in some other pairs).
It is clear that the weight of the glass will depend on the core thickness: the same stiffness can be achieved using either a thick core with few glass or a thin core with a lot of glass. It would be possible to calculate the optimum core thickness for minimum total weight (I will do it some day). I guess that light skis can be built with cores thinner than 10 mm and an amount of glass larger than usual.
Remember that the core is the heaviest component in a pair of skis.
Regarding basalt, its Young modulus is just a bit larger than the glass one, and the density is a bit lower, so I am not expecting to obtain a significant weight reduction by replacing glass with basalt.
It is clear that the weight of the glass will depend on the core thickness: the same stiffness can be achieved using either a thick core with few glass or a thin core with a lot of glass. It would be possible to calculate the optimum core thickness for minimum total weight (I will do it some day). I guess that light skis can be built with cores thinner than 10 mm and an amount of glass larger than usual.
Remember that the core is the heaviest component in a pair of skis.
Regarding basalt, its Young modulus is just a bit larger than the glass one, and the density is a bit lower, so I am not expecting to obtain a significant weight reduction by replacing glass with basalt.
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FrontierSkis
- Posts: 21
- Joined: Thu Jan 21, 2010 11:26 am
- Location: Calgary, AB
Hey Guys, First Post! But not new to this form. I have been thinking about running a similar layup as 333, something like this
Base
VDS over edges
10oz Biax
6oz Biax
Core (3mm 12mm 3mm)
10oz biax
6oz biax
Cotton graphic
6oz biax or maybe even less
What do you guys think? Will this be too soft, (looking for a softer powder ski)
Base
VDS over edges
10oz Biax
6oz Biax
Core (3mm 12mm 3mm)
10oz biax
6oz biax
Cotton graphic
6oz biax or maybe even less
What do you guys think? Will this be too soft, (looking for a softer powder ski)