Ski Builders Forum

twizzstyle wrote:

SleepingAwake wrote:There is no such thing as over pressing. Or pressing too much resin out of the fabric.

I think a lot of folks here would disagree with you

I know. But trust me, I'm an engineer

And I know that there are some manufacturers pressing at 14 bar, which I believe is more than 3.1 bar (= 45 PSI, and they press with this kind of pressure on the whole surface, not three separate hoses)

The thing is, if there are bubbles in the laminate and pressure is applied, then the bubble/resin mix is pushed out of the fabric, and not just the air. With more pressure the bubbles get smaller. But they don't disappear. So the only way to get a perfect laminate out of the press, is to start with a perfect laminate. With the press you just influence the fiber volume fraction...

Cheers, Reto

You were doing ok until you said "I'm an engineer"

Reto is right when he compares our fire hose pressures with bigger companies with "pillow case" air bladders. They are pressing at the same pressures but with full surface contact on the cat track equalling way more pressure at the skis.

I would like to keep my hoses flater when inflated, but then you have to make the gap smaller, and getting the planks into the press would be a real pita.

With three 4 inch hoses I have the hoses touching each other and no gap between them where they press on my cat track. So I am pretty close to the same effect as a single large pillow.

With three 4 inch hoses I have the hoses touching each other and no gap between them where they press on my cat track. So I am pretty close to the same effect as a single large pillow.

I think you guys are forgetting companies pressing at 90psi are useing prepreg composits and cure temps around 220f. Different story than wet layup and our cassetts or lack there of, they have heavy cassettes that are all milled to deliver even pressure midski to tip. Different world.

SleepingAwake wrote: I know. But trust me, I'm an engineer

(that makes two of us )

Also we don't need to muck up gav's thread arguing about pressure. We do that enough everywhere else.

On the sandboard - did you do a normal ptex base? Does it still have/need steel edges?? I know nothing about sandboards.

twizzstyle wrote:

SleepingAwake wrote: I know. But trust me, I'm an engineer

(that makes two of us )

make that three

get those pics up gav

gav wa wrote:You were doing ok until you said "I'm an engineer"

I honestly don't give much for all the titles. Some of the smartest and best coworkers so far where the ones with the fewest diplomas. That's why I put the smiley there. But provably I should stop trying to daff around in anything else than my native language...

@MontuckyMadman
I don't think it's a different world. The physics are the same if prepreg or not. A prepreg at high temp or a by hand impregnated fabric do behave the same way. Except the amount of resin is better controlled for prepregs. Or why do you believe it should be different? Am I overseeing anything?
But anyway. Standard pressure in sky industry is probably around 6 bars (90psi) also without prepregs. For the prepreg guys it's more like 200 psi!

Q. How do you know if someone is an engineer?
A. Dont worry, they will tell you

200 psi? that would be upwards of 200,000 lbs of force, given a 1000 sq in laminate. My laminates are usually in the range of 850-950 sq inches.

Falls.. I have to admit you nailed it ! that's my life... except I spend more time on skibuilders, CNCZone, TGR and Pinkbike than on Facebook... especially at work

i have a 16" diameter bladder. its bomber, but i dont think because its wider it's actually doing any more than what 2 8" hoses does. psi=psi, i guess you could say my contact patch is greater, thus increasing total force on the part.

Anyway, pressed my last deck at 50-55 psi, came out beautiful , and light!!