Problem solving help

vinman · Post by **vinman** » Sun Sep 02, 2012 3:23 am

Thanks brazen, I am now more concerned with what type of flex I'm going to create here. This guy wanted a light-beefy BC ski. Kind of a tough combo.

A noodle won't do for this guy.

These cores only weight in at 1 lb 10 oz. so the weight will be on target but Im really trying to beef up the stiffness.

I guess there is really no way to know except just try.

I think the top layers are close I guess I just have to figure out how. Uh carbon to put in the bottom.

20 strands might be too much, maybe 12 each ski.....

vinman · Post by **vinman** » Sun Sep 09, 2012 4:55 pm

I'm still hashing this out

What I'm now thinking about is the order of which I lay these composites out

We know that a reinforcement has a great effect the further away from the core that it is placed. Twizz wrote some good posts to this effect a while back.

So what I'm thinking is

Veneer top sheet (paperbacked birch) .7mm thick (this will help some)
11oz carbon fiber diamond with 8 strands of full lenght 3Kcarbon tow
22 oz glass with long fibers away from core
4 strands basalt fiber tow running at an angle between contact points
10.6mm core
4 basalt strands as above forming Xs underfoot (beef up torsion)
FG with long fibers down
16 strands of carbon
VDS
base

I think this is the best i can do for this guy, any ideas?

More · Post by **More** » Sun Sep 09, 2012 6:35 pm

This might be a stupid idea.... But if the underlying problem is that the core is too thin, what about using a layer of veneer or two on top of the core, then proceeding as originally planned?

edit: ohhhhh. sidewall. ignore me.

Richuk · Post by **Richuk** » Mon Sep 10, 2012 3:37 am

I think you are right More, just add a veneer to the bottom. The veneer would be the size of the base, less the width of the edge set ... offset 8mm.

Usual layup ... fibre, veneer, core etc. It will raise the core up by about 0.6mm, without any evidence of the issue shown on the sidewall. Just need to make sure the veneer is saturated really well in this instance, otherwise it will upset the fibre.

vinman · Post by **vinman** » Mon Sep 10, 2012 9:19 am

Only problem with adding veneer to the base side of the core it that I've already rabbetted the sidewalls.

I could double up the top veneer though...

I'll have to think about it some. Thanks guys.

More · Post by **More** » Mon Sep 10, 2012 12:06 pm

you'd want to do it under the fibre layers I think Vinman... Isn't the spacing of the fibre layers out from the laminate centre a pretty key contributor to stiffness?

vinman · Post by **vinman** » Mon Sep 10, 2012 1:21 pm

Wouldn't adding anything that thick to the base side give me a convexity issue?

twizzstyle · Post by **twizzstyle** » Mon Sep 10, 2012 2:02 pm

Yeah keep the materials under the core flat, you don't want to ruin the base flatness.

And yes, distance from the laminate center is a huge player in bending thickness, but if you're just trying to get back to your original design, you probably do want the extra layers under the composites (but on top of the core)

vinman · Post by **vinman** » Mon Sep 10, 2012 3:13 pm

I think if I add any extra layers I'll add more carbon tow on the bottom. The cabon tape I have for the top is 12k strands/ 144k/ inch. The other tow I have is likely 3k. This fabric was carbon-basalt hybrid and the only cloth of this kind I can find on the net is 3k carbon.

So if I go with multiples of 4 I can come close to the weight of the carbon on top.without having a finite shape of stitched fabric creating base flatness issues for me. Thinking about it this way I'll need a lot more strands of carbon on the bottom.

What will the heavier carbon on the top do to my camber? Crap.... Likely a decrease in camber or increased camber? Crap...

Maybe I should just go with a diamond of glass on top with some carbon tow to back it up to not have unpredictable camber behavior?

I only have 12 feet of the heavier carbon tape. I could split it in half to get 24 feet of 1.5 inch material and just do a full lent carbon strip top and bottom with a diamond of glass under foot on top....crap

MontuckyMadman · Post by **MontuckyMadman** » Tue Sep 11, 2012 3:01 pm

Pretty amazing you are still deciding what to do here.
Few things.
I did a layup like the afterbang all veneers and I did not rabbit as the materials were too thin and I had completely flat bases. so ymmv.
I used some 2.5 inch wide carbon uni 12oz for the length of the core on top only, in one pair with a standard glass and core layup that I knew how it would flex as I have built the same ski before and I am afraid it will almost be unridebly stiff.

vinman · Post by **vinman** » Tue Sep 11, 2012 3:42 pm

The only reason I'm still deciding what to do is that the guy these are for isn't available to come help build them for a few weeks, so my brain goes into overdrive thinking about how to make these come out as good as possible.

I think I'm just going with a 1.5 inch strip of the 11oz carbon top and bottom with a diamond of glass on top and maybe some basalt to beef up the torsional component and hope for the best, it seems that is the best I can do.

Thanks for the help everyone.

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Problem solving help