Ski Builders Forum

OMG I love those boards!

regarding the resin - most resins (at least the ones I'm aware of) will get less stiff with a higher curing temperature. The Glass transition temp will raise, which is important if the part is used at higher temperatures, but pretty useless for a snowboard/ski.
So if you have the time I don't see the reason to cure at more than 35...40°C

hmm, everything I've read independently and learned from family members in the aerospace field is that resins resist impact, cracking and adhere better after their specified temp cure from linking up and forming longer molecular strands.

Yes you are certainly right about impact resistance and ultimate strength. But thats not really a concern in a ski. Stiffness of the resin is what you need to avoid buckling of fibers under compression loading. Ultimate strength is not relevant as the fibers under compression typically fail at an elongation of around 0.5% or thereabout which is miles from what the resin can handle.

So I just picked a random resin from Sicomin as they provide all this data:

SR1700/SD2803
Youngs Modulus after 10 days @ 23°C : 3900MPa
Youngs Modulus after 16h @ 60°C: 3400MPa
Youngs Modulus after 8h @ 80°C: 3350MPa

This is a difference of 15% in stiffness which is quite significant.

Cheers, Reto

As long as you hit no stones impact resistance is not important


P.S. nice boards!

Did you ever damage the fiberglass layer of a ski with a rock strike? First thing that goes are the edges and sidewalls anyway and the toughness of the resin won't help much with that.

On mass production skis many times .. unfortunately.

But dont know if the resin makes a difference with things (impacts) like this

U must consider. CUring at temprature prevents a resin poor lminate. At room temp you can press too much of the reain out leving a dry composite that is stiff but brittle nd prone to delam.

mammuth wrote:On mass production skis many times .. unfortunately.

But dont know if the resin makes a difference with things (impacts) like this

I wouldn't call that impact damage. It's rather some form of scraping/abrasion. If the base would not have been completely damaged in that area but would rather have transmitted the load you could speak of impact. Then you would maybe see different damage behaviour for different resins.

stormyclouds - these boards are amazing! they look super fun.

Where along the camber profile are you beginning the early rise?

How does that deep swallowtail on the first three ride? Ever tried it on hardpack?

Thanks guys! Burnside, here is a pic of the nose profile.



It barely rises in front of the inserts so when you step on the camber between the feetit causes the nose to lift. I also like a lower nose height to promote lift and prevent plowing snow.

I just finished this one last night and it's on its way to Utah. I;m really loving the Matte Isosport topsheet

MontuckyMadman wrote:U must consider. CUring at temprature prevents a resin poor lminate. At room temp you can press too much of the reain out leving a dry composite that is stiff but brittle nd prone to delam.

It's not the first time I read things like that but in all the meachnical tests I have done on all different sorts of fibers and processes I have never seen any evidence of laminate performance decreasing. In fact the highest FVF possible is what everyone is after, knowing that the theoretical max is around 90% and noone gets even close to that. And after some googling I did not find any paper to suport that. Where does your expirience/theory come from?

And I can't see the logic behind it as if you heat the resin the viscosity drops quite significantly before it actually cures. So if anything I would guess one can obtain a better FVF when heating - but this is just a gutt feeling and nothing more.

On mass production skis many times .. unfortunately.

But dont know if the resin makes a difference with things (impacts) like this

This is a rock stricke after an impact with your ski, I agree with you an that, but it's not really an impact damage due to the shock. And as you wrote, I doubt the resin would make much of difference.

Cheers, Reto

Hey stormyclouds boards are looking great.
Just wondering what issues you've been having with the veneer topsheets?
I tend to agree with you about durability, I've done a lot of veneer topsheets and they can look beautiful but i dont find them durable. Ive been adding a fairly large 45° angle to the top of the sidewall all around and this seems to help a lot.
I tried a super hard topcoat once too but it cracked from not being flexible enough.
I've actually been doing some tests with tinted resin and clear topsheet very similar to what you're doing and for the same reasons.