fiberglass and carbon proportions O_O! - Page 4

> Brazen wrote:You can use mylar in place of a topsheet in the press, then pull the mylar...comes right off. Leaves a great finish.

True! Gives a great shiny finish

So the Mylar will give the epoxy a shiny finish instead of dull like with the parchment?

Polyprop, used by florists to wrap flowers. Long lengths and about the right width. Just need to check the quality of the material.

Suspect there will be issues with UV damage long term ... will be issues with edge strike, if anyone is thinking this is a straight out of the press solution. It should provide an ideal surface for obtaining a smooth flat final finish.

I've not made a CF ski yet, but I did just get some in the mail last night, so soon (hopefully soon enough to ski 'em once or twice before summer sets in). I will say with FG that using release film for vacuum bagging in place of the top sheet gives a really nice finish (and you don't have the weight of a topsheet).

I'm going to do a uni carbon, +/- 45 biax FG stack. Not decided on whether the FG or CF will be on top. I plan to do a test layup with each and see which looks better, then make the bottom symmetrical.

^^I am planning a hybrid lay up like that as well to see if

1. It's lighter than a full glass layup

2. More pop than full glass

3. Stiffer than full glass

I was thinking about 9oz uni carbon and 17oz -/+ 45 glass. I might throw some carbon tow on a 60 deg angle also to be sure it it torsionally stiff enough.

I'm going way lighter than you.

If you look at the breakdown of triax FG, it's something around 50/50 for what's in the 0deg vs. +/-45 direction. It's a little off from this, but I can't remember which is which or what's the site that actually has it laid out to look it up again and don't have the time to search right now.

So, for a 22oz triax equivalent, let's say that's something around 11oz in the 0deg and 11 in the +/-45deg. Assuming CF is 3x as still (like the beginning of this thread asserts), I've gone with 4.4oz uni CF (which should be equivalent to about 13oz FG) and 12oz bias FG. I was going to get 9oz bias but fiberglass supply was all out (this is for a pair of backcountry skis). So I think I can get away with a slightly thinner and/or less stiff core (material) and get ~equivalent stiffness to the aforementioned 22oz triax that I've used in my previous skis.

If you're using 9oz CF and 17oz bias FG, you're going to be heavier for your composites versus "normal" weight triax so, if you change nothing else for the design I'd wager that

1. It's heavier than full glass

2. I know nothing of pop, but I'd guess there'd be more

3. It will be much stiffer.

but I suppose your could win on weight depending on the density/stiffness of the core you're comparing and if you use a thinner core. I haven't done the math (I'm sure someone has), but since stiffness is proportional to the square of half the thickness of the core, I tend to think that you win the most on weight while maintaining stiffness by staying with about the same thickness core and using a lighter composite stack. Obviously this is more true for a lighter core than a heavier one.

Great info FD. I'll have to think this layup out a bit more I think.

I did a layup with 12oz biax and 5oz uni carbon, turned out a little soft with my core profile so I put a wood veneer topsheet and the ski is a great lightweight med stiff backcountry ski.

MM, did you use the same core to get the slightly floppier skis? That's actually what I'm looking for since my backcountry boots aren't super beefy (Dynafits Zzero4)

Pressed the skis, no topsheet. Flashed, flexed and put a wood topsheet on to finish the stiffness. Comprende

MM do you think the 12oz with something beefier like 7 or 9 oz carbon would have done the trick? How thick of a core did you use? Maybe throw some carbon tow in on the 60deg axis?

Or maybe the 17 oz biax with the 7oz carbon?

I'm going for the proverbial lightweight beefy backcountry ski with this build.

Yo comprendo your layup. What I'm wondering was what the core dimensions were compared to a full FG ski that *was* stiff enough prior to the wood topsheet. If such a thing ever existed, that is.

IOW, when you say
> turned out a little soft with my core profile do you mean you used the same core profile as other skis or did you make a special (thin???) one for these skis?

Really appreciate the input, BTW.

Yeah standard core but .5mm thinner. 2-11.5-2.2 ski dims were 135-106-122 @188cm and core was 168cm core profile also had a flat spot set back from center and about 30cm long.

Schweet. Good to know. That helps with my design. I think my initial attempt to use some leftovers as an extra thin core isn't going to happen. Thanks again.

I'll likely just go with my standard core of 2.2/12/2.2 and use the 12oz biax and 7 oz uni carbon with some 12k tow on the 60 deg axis. I will probably put an extra layer of glass underfoot as well for extra beef in the binding zone.

My core will be basswood with maple finger jointed into the binding mount plus a perimeter stringer of ash. I think I ca get a nice light yet somewhat stiff touring set up with this config.

Resurrecting this thread once again. I’ve been away from building for a couple years but ready to have another go around.

I’ve searched many threads looking for info on carbon/fg combinations. One thing I’ve learned is there is no single answer... I talked with a guy at fiberglass supply and he recommended trying 12oz bias fg and 4.4oz and 6.7 oz carbon uni.

My current design is a core of red cedar, bamboo stringers in binding area and ipe side walls. 2.2 11.5 2.2. The shape is 140 112 120 semi pintail with early rise tip. I’ve built a number of these and am looking for a light touring ski. Thought I’d try -

top sheet

6.7 carbon uni

12oz fg biax 45/45

Core

12oz biax

6.7 carbon

Base

I’m curious what the results were in similar lay ups in this thread and if I’m way off base. Carbon’s not cheap

I made some quick calculations based on your info and compared it to my go to flex profile. The numbers are not overly precise but should be close enough (unless you planed to use high modulus carbon...)

The tip is 16% stiffer than mine, the center is 60% stiffer than mine and your tail is 15% less stiff (...insert joke here).

On top of that 6.7oz uni carbon really is on the light side. And I think skis with uni carbon (mostly) suck.

My proposition would be to go with something like that:

uni glass

biax carbon

core

biax carbon

uni glass

The main weight saving in a carbon ski comes from the thinner core, not the lighter laminate. It's actually really rather hard to design a carbon ski as carbon is just really stiff so the core needs to be really thin to get some flex, which means you need a lot of carbon otherwise it's going to break which means you need a thinner core and so forth. I would recomend sticking to uni glass unless you know what you are doing. Which means you design the core profile based on your layup, and not the other way round...

I hope that helps for starters...

Thanks for the reply SA. Well, I already have the carbon and glass so I’ll take another look at this. I have 20 and 22 oz triax as well so I can mix and match and come up with something

Just curious what you were comparing to my layup to?

Cheers, Bill

Thanks for the reply SA. Well, I already have the carbon and glass so I’ll take another look at this. I have 20 and 22 oz triax as well so I can mix and match and come up with something

Just curious what you were comparing to my layup to?

Cheers, Bill

> bhenry wrote:Thanks for the reply SA. Well, I already have the carbon and glass so I’ll take another look at this. I have 20 and 22 oz triax as well so I can mix and match and come up with something

Just curious what you were comparing to my layup to?

Cheers, Bill

I compared it to my freetourer with similar dimensions (105mm underfoot, 1850mm length). But I used the same flex profile for a multitude of freeride skis now.

FWIW, I agree with SA. If you are trying to lose weight with a carbon/glass layup and not get an overly stiff result, I would use carbon for your torsional stiffness and fiberglass in the O degree or longitudinal axis. You could cut your uni carbon in patches and lay it in on the +- 45 angles.

Thin fabrics and single layer unidirectional glass can save several ounces of resin weight in addition to lower fabric weight from a thick triax weave.

Well, my son came home for break with one ski. The other one is up at Mt. Baker after a deep day. So, we made a new mold top and bottom. Twin tip 140/115/135. The cores are same as above. My son used 22 oz triax top and bottom with 2" carbon tape on bottom. Mine are 6.7 uni/ 12 oz biax fg top and bottom. My version is a bit stiffer and actually about what I was hoping for( imagine that). We'll be out this weekend to give em a go.

Weight- mine- 1850 g

his- 1950 g

hello,

in the previous board that i built there were 2 layers of fiibrglass which i ordered from skibuilders store. they are 744g/m^2 each, so for the whole board i had 1488g/m^2.

now, for my new boards i wanted the top composite layer to be Carbon (for strengh and to get a black color under the topsheet).

My question is: how do i know what weight the carbon should be? same as the 744fiberglass or lighter cos the carbon is stronger?

how will i know the board wont turn too stiff?

What are the proportions between Fiberglass and Carbon ?~!?~!

help!!

tnx(:

There are too many variables to just give a quick answer.

It will completely depend on the weight of the carbon you get, the style of weave, the direction of weave, etc.

Also if you are doing heated cures, it might be a good idea to do the same layup on either side of your core (if you put one layer of carbon fiber on top, put it on the bottom as well). If you don't, when the board cools you could get some drastic camber changes (different thermal expansion between the carbon fiber and fiberglass, and core). But if you go overkill you may end up with a board that is too stiff or too poppy.

im not doing heated cures.. is it ok to do the 'carbon at top fiberglass at bottom' layup??

i still need an answer about the weight of the carbon...

the fiberglass is 744g/m, 3 dierctions weave(o,45,90). and lets say the carbon will be also 3 directions.. what weight do i need?@!?~!?~!?!~?~!? helpppp

Latest field reports would suggest that a single layer of carbon above the core may not improve performance noticeably.

Better go with a layer below and above core.

Carbon has three times the strength to weight ratio as glass.

Thinner core profile for use with carbon. 8 oz uni carbon has been suggested to me. I will get more details from my sources.

I think it was uni, maybe biax.

Hope this helps to confuse.

so you are saying that 744g/m fiberglass = 250~g/m carbon??

what is uni ?? some kind of a weaveO_o?

and how come it wont improve preformance, isnt carbon much more strong/tough/cool/durable/sexy?

Ok, lets stop a minute and think about this technically.

Uni means unidirectional, i.e. fibers all running the same direction, no woven pattern. If you're going for looks, this isn't what you want, but if you're going for function, this is what you want. Having carbon fiber at 45 or 90 deg to the ski is overkill and a waste of CF, personal opinion.

When a ski flexes it is bending upwards. Carbon fiber is much stiffer than fiberglass (strength, and stiffness are two very different things, we don't care about strength in this case, stiffness is what matters). Carbon, or fiberglass, takes a lot of load in tension, but almost nothing in compression.

When you flex a ski upwards, the top is under compression, bottom under tension - that is why carbon on the top doesn't do a whole lot. It will change the stiffness when flexing the opposite direction, but that isn't often. Carbon on the bottom would make a much larger difference because then you are putting the carbon in tension. Putting it on both sides is really just to make sure you don't get cure-related camber changes due to a non-symmetric composite layup (non-symmetric about the core). But again, if you're not doing heated cures, that might not matter?

You really can't just say "this much carbon fiber gives the same stiffness as this much fiberglass" without having stiffness data for each material. You can probably find modulus of elasticity data online, but it could vary even between manufacturers of the material.

Really - you'll probably just have to experiment and make a few skis with different layups until you find what you like.

Also, side note - there are so many other variables with handmade skis that trying to come up with a perfect fiberglass/carbon combination might be moot anyways. Big one being core thickness. Stiffness of a beam (ski) is proportional to the cube of the thickness. So if you get your thickness off even a little, it will make HUGE differences in the stiffness of the ski. So if you are going to experiment, make you sure have very accurate and repeatable ways to make a good core, or you won't be able to attribute ski differences to material differences.

this I have in an email from a bit back from a pro:

> I'd suggest and eight ounce. However, 45/45 will only give you torsional rigidity and not stiffen tip to tail, You'll need to back it up with some 0/90 for that.

0/45/45 deft triax would be best.

This makes NO sense to me.

Try aspen core, 12mm on center/high point, even taper to 2.3mm tip/tail, or maybe 10.5mm poplar core on center even taper to 2mm and 8 once uni CF top and bottom?

Think you need another axis to provide more torsional stiffness.

What is your weight and height?

What are you ski dims?

What is your application? ie: BC light weight, or inbounds hard slammer or a % of each?

I ordered some 1" carbon tape a while ago and I was going to run stringers on top, like line, but I think I am finally convinced to do them under the core. Hope it will do something positive.

I will be using heat. Thanx KRP. Do you think expansion/contraction will pose a significant problem?

Thanks a lot for the answers^_^!

btw im building snowboards not skis..

my conclusions and questions:

1. carbon at top only is useless bocs it will be under compression and not tesion. in that case the only good thing about it is the looks.

2. uni is best? that sounds odd.. are you sure it will be good for a snowboard?? cos i need torsional rigidity and if i got it right uni wont provide it..

3. why having 45 or 90 deg cf will be a waste of carbon? and what do you mean by overkill O:

4. the wieght should be aroung 225g/m.

MountuckyMadman were those questions aim to me? your msg is kinda confusing

> kipi wrote:
2. uni is best? that sounds odd.. are you sure it will be good for a snowboard?? cos i need torsional rigidity and if i got it right uni wont provide it..

3. why having 45 or 90 deg cf will be a waste of carbon? and what do you mean by overkill O:

Having it at 45/-45 is goodness, that will provide torsional stiffness as you say. Imagine twisting a ski (or snowboard). What you are doing is putting it in tension at 45 deg, and compression at -45 degrees. Twist it the other way, and that reverses. So again, its all about tension/compression.

Having fibers at 90 (going across the ski/board laterally) gives it lateral stiffness. The width-to-thickness ratio of a ski or snowboard is such that you really don't get any bending sideways. Grab a snowboard by its edges on the side, and try to see if you can bend it - you can't.

So this is why 0/45/45 is popular (thats what tri-axial weave is) for skis/snowboards because you get longitudinal stiffness as well as torsional, but no lateral. I have never seen a triax woven carbon, so you're stuck with uni or biax (which comes in a variety of weaves, twill being the most popular for looks).

> MontuckyMadman wrote:
I will be using heat. Thanx KRP. Do you think expansion/contraction will pose a significant problem?

Depending on how much CF you use, yes it could. If you do it symmetrically about the core (same layers of material on both sides of the core, in the same order in the same direction) you will have no problems. If you do things differently on top than bottom, you might get camber changes.

Two examples:

Symmetric layup (top to bottom)

Topsheet

0 deg fiberglass

45\-45 deg fiberglass

0 deg carbon fiber

Core

0 deg carbon fiber

45/-45 deg fiberglass

0 deg fiberglass

Base

Asymmetric layup

Topsheet

0 deg carbon fiber

45\-45 deg fiberglass

0 deg fiberglass

core

0 deg carbon fiber

45/-45 deg fiberglass

0 deg fiberglass

Base

You'll see there isn't much difference, but its enough that when cured with heat, you could get hefty camber changes.

Also remember that where you place the various fibers in relationship to the core can have big effects on the stiffness. (closer to, or farther away from the core). Having a composite layer further away from the core will give you a stiffer resultant ski/board. Remember that stiffness = E*I, E is a constant property of the material (modulus of elasticity) I is a function of the geometry (a rectangle in the case of skis/snowboards) and layup. The further you are from the center of the core, the higher I is, and the stiffer the ski is.

I will just say that bamboo core vs bamboo core with carbon stringer on top = very different. I definitely want to try to adding more carbon to our skis to help drop the weight down. It is something my engineer and I have been talking about for awhile with a new BC version of one of our models, and if we like the layup, we might swap everything over to it. But I would say at least in my experience, carbon on top of the core adds noticeable pop and responsiveness.

> iggyskier wrote:I will just say that bamboo core vs bamboo core with carbon stringer on top = very different. I definitely want to try to adding more carbon to our skis to help drop the weight down. It is something my engineer and I have been talking about for awhile with a new BC version of one of our models, and if we like the layup, we might swap everything over to it. But I would say at least in my experience, carbon on top of the core adds noticeable pop and responsiveness.

I suppose I should add a caveat to my remarks about carbon on top doing nothing in that some ski companies do only put carbon on top just like you guys are doing, so obviously it works - I just struggle from an engineering standpoint to understand why. I know Line skis (at least a few years ago) only had carbon on top. K2's have carbon top and bottom, but its woven into the whole seamless fiberglass sleeve around the core, and now that K2 owns Line maybe they do it differently.

When you say you guys want to use more carbon to bring weight down, are you planning on cutting down core thickness and making that back up with carbon, or cutting back on fiberglass and making that back up with the carbon? Maybe a combo of both I suppose.

You need about three time less carbon to get the same stiffness.

Carbon under compression is just a bit stiffer than glass, while in tension is much stiffer, so it is better to put a layer under the core than above the core.

I dos not really matter what the big companies are doing.

Carbon also springs back to its molded shape quicker and with more force than fiberglass. This is what we refer to as snap. That is why adding carbon above the core can effect the feel of the ski. CF is not strong enough under compression to replace x amount of fg with 1/3x of cf, but you can use lighter glass and supplement it with cf, with no increase in weight, but an increase in snappiness.

At least that's my theory.

> doughboyshredder wrote:Carbon also springs back to its molded shape quicker and with more force than fiberglass.

That = stiffness.

> twizzstyle wrote:
> doughboyshredder wrote:Carbon also springs back to its molded shape quicker and with more force than fiberglass.

That = stiffness.

Nope, rebound does not equal stiffness. For example a super stiff piece of steel will not rebound to its original shape once deformed.

> The stiffness, k, of a body is a measure of the resistance offered by an elastic body to deformation (bending, stretching or compression).

where

P is a steady force applied on the body

δ is the displacement produced by the force (for instance, the deflection of a beam)

Well you're talking about two different things there: plastic and elastic deformation. A piece of spring steel will spring back and won't deform, as long as you don't bend it too much.

The difference between carbon (or fiberglass) and metal, is that there is much less plastic region before it fails. Carbon will just take a load of force without much deformation, then break. Where as steel will bend quite a bit in the plastic region (depending on the kind of steel obviously) before it fails.

You said carbon springs back with more force, that's because its stiffer (stiffness is just a force per displacement). But we're off topic now

I'm not an engineer, but I smoked with one the other day.............

anyways, somewheres I have seen a specific measurement for rebound of a material, and it definitely is not measured in stiffness.

I am of the understanding that a piece of carbon fiber with the same stiffness (same force required for deformation) as a piece of fiberglass will rebound faster than the fiberglass.

Are you saying this is not correct? (not arguing, just trying to understand)

So, if two items have the same stiffness they will rebound the same? I don't think so. I think there is another factor being left out of the equation. I have read about this somewhere, but haven't been able to find it again.

I am an engineer - aeronautical, but I had to do a fair bit of composites and structures stuff back in school.

I suppose the only thing that could cause differences in rebound speed would be damping of the material. Where as stiffness gives you a force per displacement, damping gives you a force per speed (shock absorber on a car for instance... more force the faster the shock shaft moves).

But I think the difference in damping between carbon fiber and fiberglass might be negligible assuming they have the same amount of resin, but thats a total guess.

I still think that yes, if you have a carbon fiber beam and a fiberglass beam of the same stiffness, they will rebound the same. I could still be missing something though...

Elastic Recovery is what I was looking for.

Which is directly related to modulus. I.E. stiffness.

So a cured piece of cf with the same stiffness as fg will absolutely rebound the same.

But, that piece of cf will be lighter than the piece of fg.

thanks twizz, you're a smart dude.

> doughboyshredder wrote:
So a cured piece of cf with the same stiffness as fg will absolutely rebound the same.

But, that piece of cf will be lighter than the piece of fg.

Exactly, not only lighter from less fiber, but less resin too!

> twizzstyle wrote:K2's have carbon top and bottom, but its woven into the whole seamless fiberglass sleeve around the core,

Are you referring to the carbon stringers running down the top of the cores I see in lots of K2 skis from the past 10 years or so? Does this mean there is another stringer under these cores too?

If carbon is similar to fiberglass in compression but stronger in tension, wouldn't carbon only on top lead to a ski that feels like a fiberglass ski as you load the ski in a turn or in deep snow (hopefully both) and then rebounds or snaps back to its normal shape more quickly than a ski with just fiberglass after the forces from the turn are reduced? This seems like the kind of ski that would be fun to use.

Jono, I think you're off a bit on your understanding. In a turn the ski is flexed in such a way that the top layer of the laminate is under compression. Cf is no stronger than fg in this regard. So, adding x amount of cf doesn't increase the rebound of the ski anymore than adding x amount of fg. I don't have the specs table in front of me, there may be a little bit of weight savings using cf, but you have to use much more cf under compression than under tension to match the strength of fg. Somewhere I was looking at a comparison chart of cf, kevlar, and fg, and was surprised that under compression glass is superior to both cf and kevlar.

> jono wrote:Are you referring to the carbon stringers running down the top of the cores I see in lots of K2 skis from the past 10 years or so? Does this mean there is another stringer under these cores too?

Thats right, K2 has their awesome seamless weaving machine, and it weaves the carbon right in there, top and bottom.

And remember guys - "strength" and "stiffness" are two very different things, you are talking about stiffness here, not strength.

> twizzstyle wrote:I still think that yes, if you have a carbon fiber beam and a fiberglass beam of the same stiffness, they will rebound the same. I could still be missing something though...

[physics geek]

Almost, for a spring,

F = -kx

where k is the spring constant (i.e. stiffness) and x is the displacement. So the carbon and fg beam will have the same rebound force. However,

F=ma

where m = mass and a = acceleration

So,

a=-kx/m

IOW, the 3 times (?) heavier fg beam will accelerate back 3 times less.

[/physics geek]

I mean, let's go shred the gnar, brah!

Ahhhhh, welcome feldy. Thank you for the contribution.

oh, and that means that the cf will probably feel "snappier". Right?

I guess. I don't mean to sound flip, but I don't really know what it really means for a ski to be snappier or have more pop. I just haven't skied all that many different skis and very rarely have I ever skied two different skis back to back. But I gather these things are pretty much the same?

I have been wondering for quite a while what would happen if you did a blind "taste test" with multiple different layups all with the same shape. I wonder if the average skier/rider can even feel any difference with additional reinforcements, dampening, sidewall bevel, etc.... I venture that it's only the top riders that can feel any significant difference, and I wonder how much of that is perceived and not actually real. And how much of it even matters in pow?

Yeah I'm definitely with you on that doughboy. I mean, I can certainly tell a difference if I go from a super soft ski of mine to a super stiff ski. But I have two pairs of Line 1260's, very old ones that have no carbon, and slightly less old ones that have carbon stringers in them. I would bet if I did a blind test I couldn't tell the difference. A slight adjustment in my skiing maybe, but that would be subconscious.

And yeah... in powder nothing really matters. Lots of surface area, and softness just to keep the tips on top.

I've always wondered the same.... If you had a blind test of different ski manufacturers w/ skis that were generally the same dimensions if the avg skier could tell the difference (aside of being soft or stiff) whether one ski had a wood core, foam core, fiber glass or carbon, etc.

I thought when the "shape" ski came along it was just another gimmick from the ski industry. Happily I was wrong. However you have to adjust your style of skiing to take full advantage of the ski.

But I've seen a lot of fads come and go.... split tail skis, hole in the ski tip which Fischer has brought back for the racing stock, honeycomb. Remember the groove down the middle of the bottom of the ski? What was that supposed to do? Wonder if that will make a come back.

Determining if a ski is "good" or not seems very subjective. No doubt materials used in the ski make a difference but I've always wondered how much.

Well I hope to press my first set if skis tonight or tomorrow.

> skidesmond wrote:Remember the groove down the middle of the bottom of the ski? What was that supposed to do? Wonder if that will make a come back.

That was actually functional (although before my time...). That was before the use of ground and "structured" p-tex. A completely smooth plastic base would be sticky, you want something to break the surface tension since when skiing, you're really gliding on a very thin layer of liquid water (the friction in the skis melts the top layer of snow). The groove was a way of breaking the surface tension.

Other gimmicks that come to mind - the damping weights K2 puts on some of their skis, or the little oil shocks (these are also functional, but again... how noticable to 99% of skiers?). Or what was the snowboard company that put wavey edges? To help with cutting through ice or something? Right...

> twizzstyle wrote:
> skidesmond wrote:Remember the groove down the middle of the bottom of the ski? What was that supposed to do? Wonder if that will make a come back.

Other gimmicks that come to mind - the damping weights K2 puts on some of their skis, or the little oil shocks (these are also functional, but again... how noticable to 99% of skiers?). Or what was the snowboard company that put wavey edges? To help with cutting through ice or something? Right...

So the groove really did serve a purpose... Yeah I remember that. I think Salomon had built ceramic material into the ski that lit up when the ski vibrated. That was supposed to turn the vibrations into electricity, thereby dampening the ski. Don't see that around anymore.

I just found out about the wavy edge last year from a snowboard instructor I work with. Supposedly it gives more edge contact at certain key points to provide better carvabilty. He thought it made a difference. I was wondering when someone will do that for a ski. I've thought about it, just for grins.

I thought whatever snowboard company it was that did it, also had a run of skis with the same thing? Can't remember the company though... Libtech?

Yes it was Libtech, and they call it "Magne-Traction"...

has anyone ever used ONLY carbon fiber? Would that make the ski way to stiff? What are the main properties of fiberglass, since CArbon Fiber adds pop and snap?

This thread is old but interesting!

I only use fiberglass in my ski. And after reading this I think that I will continue to do so. Is the conclusion here that the only thing that Carbon does is to reduce weight?

doughboyshredder, twizzstyle, skidesmond and others, do you have anything to add to this, now 3,5 years later?

Many people in the forum seem to put carbon stringers in their layups, but why?

Well, I still have not tried Carbon Fiber yet but many others have. I have run some simple comparison tests between FG and CF. It does reduce weight but adds stiffness and rebound to a ski/board. There are many weaves and weights for CF just like there is for FG. For the most part my skis don't "need" CF because I use mostly hard woods (ash/maple) and 20-22oz triaxial FG, so there's plenty of firmness and torsionally rigidity. But if I was looking to make a lighter ski (thin the core out or use a lighter wood) I would definitely use CF.

So I have some triax carbon fiber from Braider that I am wanting to make a good looking all carbon ski with. I was searching for how to get a clean, shiny look to the top layer and ran across this old thread. Interesting posts, so since someone else got it going I'll add my 2 cents.

Twiz, there's possibly a bigger part than friction for the layer of water we glide upon is the fact that as you add pressure to ice the melting point decreases. Also why water expands when it freezes. I believe this is all unique to water. That and the fact that we're usually working close to the melting point (and a little friction) is what we owe to our favorite pastime.

This shows it. For all other common elements, above the split at a very low pressure (.006 atm) both lines surrounding the liquid phase will go up and to the right (increased pressure leads to a solid).

http://serc.carleton.edu/images/researc ... lor.v2.jpg

Good stuff on here regarding the weight savings of carbon adding to "pop" of a ski.

Now has anyone got any tips on how to finish a carbon top ski? My thinking is to layup the top layer of carbon with a healthy amount of epoxy, then carefully (no wrinkles) cover that with parchment paper, then top cassette, and into the press to cook. Add a urethane layer at the end to get a glossy finish.

Any thoughts?

Clear topsheet.

I'd skip the parchment myself. I good waxed AL cassette will do the trick. Clear top sheet or poly works.

If you go with parchment, adhere it to your top al sheet with spray adhesive. As the pressure is applied it will add tension to the parchment and prevent wrinkling. If you just lay it on top you'll be risking the parchment sort of slumping into the tip and tail curve....lots of wrinkles.

For a shiny epoxy topsheet, I think you can use polypropylene or mylar or other such release films. I'm not sure what Huck does, but he does it really well.

I was thinking about the clear topsheet. But Huck's board looks awesome. Thanks for the tip Richuk.

You can use mylar in place of a topsheet in the press, then pull the mylar...comes right off. Leaves a great finish.