Twizz 2010/2011

sammer · Post by **sammer** » Fri Nov 26, 2010 6:15 pm

I might be way off base here.
Never thought about it before so not sure how it works.

But,
If you have to add epoxy to both sides of your precured to get it to bond to the rest of your layup then I could see it being heavier.

sam

twizzstyle · Post by **twizzstyle** » Fri Nov 26, 2010 7:34 pm

While that's true, the actual film of epoxy between each layer should be pretty damn thin after pressing.

What I didn't do was weigh all of the materials before the layups, that would have been the smart thing to do - fail. I did measure the cores and they were all within 10g of each other. I know I mixed up, and used, far less epoxy during the layup of the pre-cured ones so the weight has to be in the fiberglass sheets. Although I didn't really compare how much squeezed out either.

Meh. Both pairs look awesome. I probably won't use the pre-cured stuff again just because of the cost, but it sure feels nice under the feet.

Richuk · Post by **Richuk** » Sat Nov 27, 2010 2:59 am

Is there something about the pre-cured that means you couldn't make it?

twizzstyle · Post by **twizzstyle** » Sat Nov 27, 2010 10:11 am

The only real benefit to it that I can see (based on what I've found from the weight) is that it is cured under tension. This just makes it more "efficient" for lack of a better term. The fibers are already taut so it is effectively stiffer. I could hypothetically cure some sheets of triax and work out some clamps to pull it in tension while it cures... but that sounds like a lot of effort, when I could just make my cores a bit thicker to make them stiffer

Richuk · Post by **Richuk** » Sat Nov 27, 2010 11:33 am

What do you think about clamping the fibre either end within the mold before pressing. Slowly adding the pressure and create the tension? Sounds improbable?

twizzstyle · Post by **twizzstyle** » Sat Nov 27, 2010 11:42 am

Richuk wrote:What do you think about clamping the fibre either end within the mold before pressing. Slowly adding the pressure and create the tension? Sounds improbable?

Clever, would probably work. But it wouldn't be easy getting the clamping just right.

rcbahn · Post by **rcbahn** » Wed Feb 02, 2011 4:14 pm

What pressure are you running? If you have more resin in a part it will be stiffer- note that it will be more brittle/weaker. If you're squeezing too much resin out of the wet layup they will be lighter and softer. Skis look good- love the graphics, what did you use to draw them?

twizzstyle · Post by **twizzstyle** » Wed Feb 02, 2011 4:55 pm

60psi for both pairs. The dry skis have less resin in them then the wet ones, it's just the pre-cured sheets that add the weight.

I disagree that squeezing out more resin will make a ski softer. Resin has a negligible modulus of elasticity compared to fiberglass.

I did the graphics with Adobe Illustrator.

Brazen · Post by **Brazen** » Wed Feb 02, 2011 5:12 pm

There's a car manufacturer across the parking lot from me...he pre-pregs some of his glass in something like a large silicone tray. I'll find out more about it. The glass comes out beautiful btw, seems like it might be nice for the "tricky" stuff, like carbon fiber twill, etc. To the touch, it has less flexibility than the preimpregnated glass that Burton uses though.

rcbahn · Post by **rcbahn** » Wed Feb 02, 2011 7:06 pm

How do you know the wet ones have more resin in them?

If you disagree with my comment I invite you to do a test, layup a small strip of FG wet on a flat surface, do the same with another piece and compress it with 60 psi- you can use plastic wrap, a board a little larger then the FG strip and some weights to achieve the correct pressure. When they are cured bend them and see for yourself.

twizzstyle · Post by **twizzstyle** » Thu Feb 03, 2011 11:00 am

rcbahn wrote:How do you know the wet ones have more resin in them?

If you disagree with my comment I invite you to do a test, layup a small strip of FG wet on a flat surface, do the same with another piece and compress it with 60 psi- you can use plastic wrap, a board a little larger then the FG strip and some weights to achieve the correct pressure. When they are cured bend them and see for yourself.

This is all stuff I've done years ago when I was in school.

Bending a single layer of fiberglass has NOTHING to do with ski stiffness. You're missing some key aspects of ski design here. Remember that stiffness in a sandwich composite beam does not come from bending the composite, it comes from putting the composite in tension and compression.

The more appropriate test would be layup one strip of FG wet, then another under 60psi just as you said, and then PULL on each strip, NOT BEND. The tensile stiffness of the two will be near as makes no difference the same.

I know the wet ones have more resin because I used about half the resin during the layup in the dry ones.

rcbahn · Post by **rcbahn** » Fri Feb 04, 2011 9:34 am

I follow you one the tension/compression of the fibers, I had not thought about it that way, makes sense.

As for the amount of resin in the skis I think it's still unknown- I am thinking that it is possible that even though you used twice as much resin during layup it is possible that you squeezed more then half during the pressing.

twizzstyle · Post by **twizzstyle** » Sat Mar 12, 2011 12:04 pm

http://b.static.ak.fbcdn.net/rsrc.php/v ... 88568&ev=0

Me and Kevin (kevywevy) at Alpental 3/11. I'm on my piggy stick v2.0, kevin's on his frumpy sticks.

Here's a cool still from pole-cam as well (I mounted my gopro on my ski pole... surprisingly awkward to ski like that)

a.badner · Post by **a.badner** » Fri Mar 18, 2011 1:12 pm

haha love the line pin poles.

AND

the go pro mount's backside tape is the 3m out door super duty stuff.
When youre done with a particular mount you can just rip it off, put the on the 3m stuff, then slap it on somewhere and not worry about having to spend 20 dollars on new mounts, ;)

how do your skis ride in the park?

twizzstyle · Post by **twizzstyle** » Fri Mar 18, 2011 1:28 pm

Funny you mention the mount. I didn't trust just sticking one of the 3M-taped mounts on the poles cause there's no way it would stay.

I took the plastic square thing the camera came on, cut off the sides on the band saw, so it was basically a gopro mount with some tabs sticking fore and aft. Then I zip tied that onto the pole, worked great.

(my poles are K2 public enemy poles, I wrapped then in the stripey tape years ago cause I didn't like the silly graphics on the poles)

The piggy sticks (the soft fatties) are surprisingly fun in the park. I used to make fun of people riding reverse camber powder boards in the park, but... I'll be damned, its actually pretty damn fun.

The dry crabbies are EPIC fun on groomers and in the park. A bit stiff for my liking for rails, but for jumps they're great. I may try out the wet crabbies this weekend (still have yet to ski those, nearly 4 months after building them). They're noticably softer so I think they'll be better for rails and general screwing around, although not as good at high speed.

I've only had one day in the park this year because the powder has been so good.

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Twizz 2010/2011