Ski Builders Forum

i have been pressing at 95psi at 180 deg F. i was wondering if i am using to much pressure. we have experienced some delams, but i dont think they are related to preasure. i have noticed that most people on here press near 45psi, just wondering if i should be doing the same.

also have any of you ever had a side wall blow out, a new ski design i have the sidewall would curve back past the side cut, it is fairly gently but just curious what your ideas are??

as always thanks so much for all advise

What is your rationale for pressing at 95psi?

To me this seems like overkill and I wonder if it could actually be pressing out too much epoxy?

I tend to follow the Bigger Hammer Theory for most things in my life. i.e. if 45psi is good 95 must be better. this theory has lead me astray before.

as for the rationale i designed everything to operate at 150psi so i figured 90 was good. do you know what the BIG BOYS press at?

No idea what psi commercial guys press at. I press at 50-60 psi and find this to be sufficient to create a good bond as well as squeeze out enough epoxy to lighten things up. Everythg seems to bond well for me a this pressure as well.

It definitely is possible to squeeze too much epoxy out. At what point that happens I couldn't say, and would depend on your specific layup and expoy selections, but don't think that you can up your pressure indefinitely and not end up with too little resin. Maybe you would be better off at something a little lower.

great ill do the next pair at 70 and see how it goes

I press mine around 60psi, but for no real reason other than the forces in the press scare me.

I press at 50 psi / 150 *f. So far so good.

We press at 75psi heated, twin blatters and a cat track, effective i believe its like stacking 15 of my Subaru's on-top of the snowboard.

-Jacob

I press at 80. Most of the big guys press between 80 and 100.

No problem with your pressure IMO, you just have to make sure all your tolerances are tight.

thanks for the input i am waiting on some carbon from raka, when it arrives i will try pressing at 70 and see how it goes and let u all know

ggardner90 wrote:i have been pressing at 95psi at 180 deg F. i was wondering if i am using to much pressure. we have experienced some delams, but i dont think they are related to preasure. i have noticed that most people on here press near 45psi, just wondering if i should be doing the same.

also have any of you ever had a side wall blow out, a new ski design i have the sidewall would curve back past the side cut, it is fairly gently but just curious what your ideas are??

as always thanks so much for all advise

Too much pressure will absolutely squeeze out epoxy and leave your fiber, resin poor. Another word for weak.

Just turning on the heat is not the way to do the job either. Resin needs to be ramped up at a varying rate. Use the heat to give you a fast cure, but then follow the correct post cure heat schedule for your epoxy. That is the ONLY way to get the full properties of the epoxy to develop. Without this post cure heat, your epoxy will be brittle and weak.

I recommend losing the press, and going with vacuum bagging using either pre-preg or resin infusion. You will get near perfect resin to fiber ratios and a much cleaner lay-up.

You were right all along though and your instincts are excellent. I bet you design cool skis.

Cheers,

Bloefeld

Bloefeld wrote:

ggardner90 wrote:i have been pressing at 95psi at 180 deg F. i was wondering if i am using to much pressure. we have experienced some delams, but i dont think they are related to preasure. i have noticed that most people on here press near 45psi, just wondering if i should be doing the same.

also have any of you ever had a side wall blow out, a new ski design i have the sidewall would curve back past the side cut, it is fairly gently but just curious what your ideas are??

as always thanks so much for all advise

Too much pressure will absolutely squeeze out epoxy and leave your fiber, resin poor. Another word for weak.

Just turning on the heat is not the way to do the job either. Resin needs to be ramped up at a varying rate. Use the heat to give you a fast cure, but then follow the correct post cure heat schedule for your epoxy. That is the ONLY way to get the full properties of the epoxy to develop. Without this post cure heat, your epoxy will be brittle and weak.

I recommend losing the press, and going with vacuum bagging using either pre-preg or resin infusion. You will get near perfect resin to fiber ratios and a much cleaner lay-up.

You were right all along though and your instincts are excellent. I bet you design cool skis.

Cheers,

Bloefeld

Maybe you should leave the recommendations to the guys that have built some ski’s and boards!!!!!

Did you hear guys Bloefeld thinks you should throw out your expensive ski presses!!!! But oh wait he has never built any ski's yet so how could he possibly know.
Very irritating man. Sorry rant over :-)

hwn147 clearly you don't understand or appreciate the value of this information. Read more - I mean a lot more.

If you have anything about you, you'll delete that post.

hwn147 wrote:
Did you hear guys Bloefeld thinks you should throw out your expensive ski presses!!!! But oh wait he has never built any ski's yet so how could he possibly know.
Very irritating man. Sorry rant over :-)

And you are?

The last skis we pressed (for a buddy) had black pigment in the epoxy and a clear topsheet. He wanted completely black and glossy. After pressing, there was a lot of fiberglass showing through. There was certainly more than enough epoxy, and the black pigment just made it more apparent how much was being squeezed out. Now I am wondering if at 60psi I have been squeezing out too much. For the next pair I might go down to 40 or 50psi.