Idea for a layup, involving carbon and aramid

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arild
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Idea for a layup, involving carbon and aramid

Post by arild » Fri May 03, 2013 2:05 am

I know, I know, keep it simple, stupid!

This might help others, though, so I´m willing to step into the flames..

I plan to build my very first (firehose) press this fall, and over the winter.

I´ve been thinking about a layup that I think might work out well, but it involves aramid and carbon, and I don´t know much about even a regular layup (except for theory), and there´s not too many threads on here regarding the use of aramid in skis.

Well, I plan to use an ash core with a maple stringer in the middle. The thickness and tapering is so far off for now, so I´m not heading too deep into that territory yet.

Around that, I think of using a biaxial +/- 45 degree carbon fibre sheet on each side, with potentially a unidirectional carbon stringer going from tip to tail on top of that, and heavy triaxial glass in a layer on each side of that again. Next to the base, I want to employ an aramid sheet for impact protection, like Igneous does.

Not using carbon fibre for weight reduction, just for torsional rigidity. Now comes the big question;

Would a triaxial carbon fibre work better on top of the core, instead of biax+stringer? Is it pointless to put carbon fibre below the core, and should I just use an additional layer of fibreglass instead?

How many layers of fibre cloth do you use in your builds, and what do you think it does?

I´m confused as hell. First topic I´ve ever made here, hope to get some information.

Thanks a bunch!

Arild, Norway.

Richuk
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Post by Richuk » Fri May 03, 2013 3:17 am


twizzstyle
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Re: Idea for a layup, involving carbon and aramid

Post by twizzstyle » Fri May 03, 2013 8:37 pm

arild wrote:I know, I know, keep it simple, stupid!
You already answered your own quesition! End of thread! :)

Seriously though, what you described sounds expensive... Don't waste the money on something that is almost gaurunteed to have a lot of errors. If this is your first pair ever, you have a lot to figure out, and you will make mistakes!! It is always very tempting to get crazy with materials, that's what gets us all excited for this stuff, but you really Ned to think about it financially. If you are ok spending the money on those materials, knowing it will likely get one day on the mountain and end up hanging on your wall, go for it. Otherwise? Do a normal triax fiberglass on your first pair to get the rest of the process figured out, then on pair number two, start experimenting.

Now if I step off my unsolicited advice train... What you described also sounds very stiff, depending on the weight of the cloths used (and thickness of your core, and probably a million other things). Aramid is a mix of carbon and Kevlar. If you are putting it in for impact protection, why not just use a biax Kevlar? You are already putting other layers of carbon, so I'd skip the carbon in the aramid and go pure kevlar. You need to figure out the weights of carbon fabric to use. Doing a biax carbon, plus uni carbon, plus triax fiberglass sounds like way too much. Stiff, and heavy. :D

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Re: Idea for a layup, involving carbon and aramid

Post by sammer » Fri May 03, 2013 8:56 pm

twizzstyle wrote:
arild wrote:I know, I know, keep it simple, stupid!
You already answered your own quesition! End of thread! :)

Seriously though, what you described sounds expensive... Don't waste the money on something that is almost gaurunteed to have a lot of errors. If this is your first pair ever, you have a lot to figure out, and you will make mistakes!! It is always very tempting to get crazy with materials, that's what gets us all excited for this stuff, but you really Ned to think about it financially. If you are ok spending the money on those materials, knowing it will likely get one day on the mountain and end up hanging on your wall, go for it. Otherwise? Do a normal triax fiberglass on your first pair to get the rest of the process figured out, then on pair number two, start experimenting.

Now if I step off my unsolicited advice train... What you described also sounds very stiff, depending on the weight of the cloths used (and thickness of your core, and probably a million other things). Aramid is a mix of carbon and Kevlar. If you are putting it in for impact protection, why not just use a biax Kevlar? You are already putting other layers of carbon, so I'd skip the carbon in the aramid and go pure kevlar. You need to figure out the weights of carbon fabric to use. Doing a biax carbon, plus uni carbon, plus triax fiberglass sounds like way too much. Stiff, and heavy. :D
Beat me to it so...

What he said. ^
But to reiterate, get your process figured out. There is way more to this than materials.
Triax works fine for almost all applications, and is already stiff enough without adding to the mix.
Once you get that figured out add one variable at a time to see how it affects that mix.
This hobby is as much science as it is magic/art (too many colors spoil the effect.)

Unless of course, you have a handful of cash burning a hole in your pocket then go ahead and blow it on "wall art"

In other words $200 paint brushes wont make you Picasso. Cut off your ear then we'll talk.

sam
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Best of luck to you. (uneva)

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vinman
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Post by vinman » Sat May 04, 2013 3:04 am

Couldn't agree more with Sam and Twizz. Way stiff, way, heavy, way expensive. Get your process down then get fancy.

I have now made 19 pair. I'm just getting to the point that I'm willing to take a chance on exotic material experiments.

I'm going to try for a lightweight ski this season. Basswood core with maple finger jointed under the binding screws, 6mm ash perimeter stringer. 17oz biax glass with 7oz uni carbon. Shooting for under 4 lbs per ski on a 183 cm ski and 107 underfoot. This will be a touring ski mostly.
Fighting gravity on a daily basis
www.Whiteroomcustomskis.com

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tufty
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Re: Idea for a layup, involving carbon and aramid

Post by tufty » Sat May 04, 2013 6:22 am

sammer wrote:In other words $200 paint brushes wont make you Picasso. Cut off your ear then we'll talk.
Can't argue with the rest, but I'm fairly certain that you're getting your painters mixed up.

http://www.youtube.com/watch?v=Kc2iLAubras
vs
http://www.youtube.com/watch?v=tHGChLGH52I

sammer
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Re: Idea for a layup, involving carbon and aramid

Post by sammer » Sat May 04, 2013 7:30 am

tufty wrote:
sammer wrote:In other words $200 paint brushes wont make you Picasso. Cut off your ear then we'll talk.
Can't argue with the rest, but I'm fairly certain that you're getting your painters mixed up.

http://www.youtube.com/watch?v=Kc2iLAubras
vs
http://www.youtube.com/watch?v=tHGChLGH52I
Thanks for setting me straight Brett. That's what happens when I start drinking beer around 3pm, skip dinner, and come home 10:30ish and try to type.
I forgot all about the Modern Lovers, thanks for that too.

sam
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Best of luck to you. (uneva)

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MontuckyMadman
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Post by MontuckyMadman » Sat May 04, 2013 11:07 am

Pretty sure aramid is geneic kevlar, no carbon fiber at all. Kevlar is the dupont brand for aramid. The processes for the production of carbon and aramid are simlar but its pretty much thermoplastic cooked nylon in both instances you just get different properties. Kevlar has the impact resistance and carbon is for stiffnes. I could be wrong as im not a materials engineer and i expect twizz would know better as he works in aerospace but i thought i had this al ready figured out.
If aramid had carbon in it al ready they wouldnt offer carbon/kevlar hybrid fabrics i would assume.
sammer wrote: I'm still a tang on top guy.

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Post by Richuk » Sat May 04, 2013 2:15 pm

Using a Kevlar sheet is going to be costly. It would need to be cut so that it sats within the edge set, otherwise there will be issues. It will be hungry for resin, so you will be adding weight and it will be a bit confusing to use more than one fabric at this stage.

Impact resistance - there are cheaper ways of doing this.

Stay with tri-axial glass until you start to determine what type of carbon fibre you want to use.

It sounds like you are looking for a soft flex, but torsionally rigid design. Playing with the dimensions of the core will do this for you (ash and maple).

SD might be a good person to help with this.

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MontuckyMadman
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Post by MontuckyMadman » Sat May 04, 2013 3:46 pm

Rich, what elze would you sugest for impact resistance?
sammer wrote: I'm still a tang on top guy.

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Post by sammer » Sun May 05, 2013 12:31 am

Richuk wrote:Using a Kevlar sheet is going to be costly. It would need to be cut so that it sats within the edge set, otherwise there will be issues. It will be hungry for resin, so you will be adding weight and it will be a bit confusing to use more than one fabric at this stage.

Impact resistance - there are cheaper ways of doing this.

Stay with tri-axial glass until you start to determine what type of carbon fibre you want to use.

It sounds like you are looking for a soft flex, but torsionally rigid design. Playing with the dimensions of the core will do this for you (ash and maple).

SD might be a good person to help with this.
Pretty much in English what all the above said...
So there is probably no denying it.
Start simple and work your way up.
Although my wife told me to mind my own business and let you do what you want... she's usually right 'though I hate to admit it...

sam
You don't even have a legit signature, nothing to reveal who you are and what you do...

Best of luck to you. (uneva)

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Post by twizzstyle » Mon May 06, 2013 6:38 am

MontuckyMadman wrote:Pretty sure aramid is geneic kevlar, no carbon fiber at all. Kevlar is the dupont brand for aramid.
You're absolutely right, I apologize! I've had that wrong for years!

Also, for what it's worth for the OP, I absolutely HATE working with kevlar. I've never used it in skis (and I never will for this reason), but I've used it in other projects before. Pain in the butt to cut. Of course, that's what makes it such an ideal solution for impact and break resistance. But you have to buy special scissors and blades for it, so factor that into your budget too.

arild
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Post by arild » Mon May 06, 2013 10:51 pm

Thank you all for your very helpful replies!

As for the ski I´m after, it´s supposed to be stiff as nails, so wasn´t planning on a very thin profile at all.

Didn´t know aramid was so tough to cut. Definitely goes in the book of "why not".

All in all, sounds like both aramid and carbon are tricky beasts to master, and yes, I should stick to just fibreglass (as stated in the OP, KISS).

Is the aramid going to stiffen up significantly in the cure so flashing really becomes an issue if I don´t precut the fibres?

The links in the first reply really helped. Learned a lot of new stuff, as did I with the rest of the replies.

Now, for dampness and torsional rigidity; is quad glass going to help with either, in addition to triax or replacing it?

And I wasn´t planning on making my first build a $400 venture into exotic fibres. Even I am not that silly.

Thank you for the replies and debate, everyone. Really appreciate it!

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falls
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Post by falls » Tue May 07, 2013 2:37 am

I think quadraxial glass is a gimmick.
Only on a super super fat ski is there going to be any flex in the core in the 90 degree plane.
Triaxial deals with torsion in the thinner areas of the core and longitudinal flex.
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twizzstyle
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Post by twizzstyle » Tue May 07, 2013 6:21 am

What Falls said, diagonal fibers give you torsional stiffness. Lateral fibers don't really do anything in a ski. In a snowboard it'll help lateral bending, but a ski is too narrow to matter.

Kevlar/aramid is hard to cut period, I wouldn't say it gets easier or harder after layup. If you cut it like Rich said so it's all "inside the ski", and no flashing to cut off, that would be the easiest (but you'll still have to get some kevlar scissors to cut the fabric)

http://www.amazon.com/Clauss-Carbon-She ... r+scissors

In my experience, cutting it after curing with a band saw, it'll turn to fuzz, pull fibers out, and just generally make a mess. Can sand it easily either. Like I said I've never put it in a ski, but I've made large RC airplane parts (and an entire 10ft long UAV out of it), and it was miserable. Carbon, on the other hand, is a breeze to work with. I love it.

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