Search found 123 matches

by SleepingAwake
Wed Nov 14, 2018 11:29 pm
Forum: Ski/Snowboard Design and Layup
Topic: Lay up sequence - carbon next to wood
Replies: 7
Views: 1118

Was curious of how much it would change a quickly ran the numbers. for a pure carbon layup: the tip is about 11% stiffer when diagonal layers are facing the core the center is about 3% stiffer when diagonal layers are facing the core The difference is bigger with flax on the diagonals as due to the ...
by SleepingAwake
Fri Nov 09, 2018 7:10 am
Forum: Ski/Snowboard Design and Layup
Topic: Lay up sequence - carbon next to wood
Replies: 7
Views: 1118

I have seen plenty of problems with carbon directly on wood. If you need to do this then use a thin glass or polyester fleece inbetween to give a tougher interface. The problem is the huge difference in stiffness that creates big shear stresses at the interface. For the same reason the diagonal laye...
by SleepingAwake
Fri Mar 23, 2018 9:25 am
Forum: Ski/Snowboard Design and Layup
Topic: Why not completely replace fiberglass with carbon?
Replies: 7
Views: 2364

Re: Why not completely replace fiberglass with carbon?

As far as I understood, carbon young modulus is 3 times greater, than fiberglass. So 3 times less is needed, to get the same stiffness. Tension strength overpowers for typical ski tension forces for both materials. So, what are reasons (except price) to use fiberglass? The problem with that is, tha...
by SleepingAwake
Tue Dec 12, 2017 12:23 am
Forum: Materials and Supplies
Topic: fiberglass and carbon proportions O_O!
Replies: 66
Views: 25183

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 d...
by SleepingAwake
Mon Dec 11, 2017 8:05 am
Forum: Materials and Supplies
Topic: fiberglass and carbon proportions O_O!
Replies: 66
Views: 25183

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 ...
by SleepingAwake
Tue Oct 31, 2017 7:29 am
Forum: Journals: Log Your Ski Building Progress
Topic: Back and looking forward to building!
Replies: 22
Views: 5012

the advantages and disadvantages of pre cured laminates i can think of right now are: + easy processing with the possibilites of doing precuts of the fibers between the recess from the edges or things like that + good consistent fiber alignment and fiber volume fraction + Possibility to use differen...
by SleepingAwake
Sun Oct 29, 2017 9:01 am
Forum: Journals: Log Your Ski Building Progress
Topic: Back and looking forward to building!
Replies: 22
Views: 5012

Ahhh, got it. Are you saying you'd have to sand the sheets before layup, or are you thinking during finishing? Sry, what I meant is after pressing the ski when trimming off the flash and finishing the sidewalls there is a lot of sanding involved and generally sanding natural fibre composites is soo...
by SleepingAwake
Wed Oct 25, 2017 6:56 am
Forum: Journals: Log Your Ski Building Progress
Topic: Back and looking forward to building!
Replies: 22
Views: 5012

doughboyshredder wrote:Also want to point out that I'm looking at pre cured not pre preg. Fully cured sheets.
This is why I wrote that sanding dust is probably more problematic and I personally would rather use a flax laminate with liquid epoxy rather than having to sand the precured glass.
by SleepingAwake
Sun Oct 22, 2017 10:51 am
Forum: Journals: Log Your Ski Building Progress
Topic: Back and looking forward to building!
Replies: 22
Views: 5012

Some cool ideas coming out simply by someone wanting to try somethung different, that's cool. I would email the info desk at Henkel, they have always really gone out of their way when i have had a question for them. They might have a VOC free option. I have always thought that VOC free epoxy had a ...
by SleepingAwake
Sat Oct 21, 2017 1:53 am
Forum: Journals: Log Your Ski Building Progress
Topic: Back and looking forward to building!
Replies: 22
Views: 5012

Hey guys I work quite a bit with entropy resins, and while I generally like their products a lot I would like to point out that it is still an epoxy and the source of the raw materials doesn't mean it's any better for your health. But with proper handling epoxies are really pretty safe to use and gl...
by SleepingAwake
Sat Oct 14, 2017 9:53 am
Forum: Journals: Log Your Ski Building Progress
Topic: Divide Rides
Replies: 328
Views: 114724

Weird thing is though.....the running length was affected more than the tips. I figured it would be the other way around as there is less wood thickness for glass to offset it the tips? This looks mint! and I actually really like the blodgynes :) Regarding the spoon - I would assume that the temper...
by SleepingAwake
Thu Oct 05, 2017 7:55 am
Forum: Journals: Log Your Ski Building Progress
Topic: 13 SKIS Building proces
Replies: 20
Views: 9798

I strongly disagree with that and I know of a few cases where this lead to problems. You generally try to have a smooth transition in stiffness in order to avoid shear stress on the interface. So always core to biax to UD. If you want to have the UD against the core I would recommend putting a very...
by SleepingAwake
Thu Oct 05, 2017 1:22 am
Forum: Journals: Log Your Ski Building Progress
Topic: 13 SKIS Building proces
Replies: 20
Views: 9798

I strongly disagree with that and I know of a few cases where this lead to problems. You generally try to have a smooth transition in stiffness in order to avoid shear stress on the interface. So always core to biax to UD. If you want to have the UD against the core I would recommend putting a very ...
by SleepingAwake
Wed Oct 04, 2017 6:31 am
Forum: Journals: Log Your Ski Building Progress
Topic: 13 SKIS Building proces
Replies: 20
Views: 9798

I do not understand what's going on in your second picture, could you elaborate?
by SleepingAwake
Tue Aug 29, 2017 2:11 am
Forum: Ski/Snowboard Design and Layup
Topic: Ski stiffness change with width
Replies: 8
Views: 4053

So i quickly run a calculation in my calculation programm. This depends on the Layup and core so those values here are not 100% exact, but the difference is probably smaller than your production tolerances (no offense ;)) In general the stiffness is linear dependent of the ski width. So a 20% wider ...