Getting close...

[BRIDGER7]

With winter on our heels we are days away from our first lay-up and press. Needless to say, we are super excited and feeling pretty good about our progress to date. We had some struggles with our first set of cores and ended up ripping a few UHMW sidewalls right off the wood core. We opted to go with maple after that. The maple sidewalls routed really well and look beautiful. We got our desired 2mm tip and tail with a little over 10 in the center. We also had to redesign our router jig to make more room to maneuver the router inside the rails. Last night we glued one set of edges to our ptex bottoms- bright orange so they shine when we rock a Daffy . Came out pretty good but we did try to weld the seams after we thought we had a good bend. This didn't exactly go as planned and the weld came apart once we had to readjust the bend. Other than those two problems, things seem to be coming together as planned.
I was hoping that some of you seasoned builders out there could provide some input on press psi. We have mill hose (2-6" sections) that is pressure tested to 125psi. I gather that there are many factors to consider when one chooses the psi range when they press. What do you guys feel is adequate? Or what factors should we look at when we are determining how much pressure we should inflate to? We are going to have a cat track installed on the press but no heat for now. We are going to use West System Epoxy- 105 Resin and 206 (I think) fast cure hardener, which takes approx 6-8 hours to cure. Another question was if we should leave the skis under pressure for the full 6-8 hours? Not sure if this makes a difference regarding the questions I threw out there but we will be covering the bottom mold with masonite and plastic and, we are planning on having some sort of top cassette sheet to cover the top of the skis.

Thanks in advance for any input!
Bridger7

[chrismp]

it's hard to give you an exact number...read this thread and you'll see why: http://www.skibuilders.com/phpBB2/viewt ... e+laminate

[twizzstyle]

For your first press, whatever, just pick a number. 50psi? Sure.

Yes you definitely want to leave it under pressure until it's cured.

[Sherpa Burns]

A good range is 45-55. If I press higher than that, I usually end up with texture of the glass showing through the topsheet. 45-50 is just about right for a perfectly flat top, adequate squeeze out, and properly bonded layers.
As Twizz said, leave under pressure until fully cured.
Have Fun!

[petemorgan(pmoskico)]

I would recommend using the slow cure hardener (thats the 206, the fast is the 205). your pot life is pretty short with the fast cure, and the gel and working time with the fast is not long also. cure time on the slow cure depends on factors but it isnt too bad. its a safer bet to use the slow cure.

no need for using heat when using west systems. that epoxy works great at room temp of 70 degrees. i built a insulation box around my press thuogh to heat the ambiant temp to 90-100 degrees to speed things up. you can even press at temps lower than 70 degrees and then do a post cure out of the press. read about it on their website. great info there. west systems epoxy is a great resin system in my opinion

the slow cure epoxy doesnt take that long to cure under pressure. i usually leave my skis in for 24 hours. at 90 degrees which is excessive, but i figure the wood could use as much persuasion to bend and stay bent.

plan on 1 hour for your first layup (that is if everything goes well). i always use the slow hardener. i have even used the extra slow hardener, as a promotional/sample product from west systems.(they have great customer service!)

word of caution, dont mix up all the epoxy at once. (you might already know this) a larger volume will start to kick exponentially faster. I mix 12 ounces at once. One time i mixed 20 ounces and it starting kicking in the pot in about 5 min. Started exotherming and smoking. Bad news


go onto west systems website, there is an abundance of info, and it is one of the easiest epoxies to use. no heat required, and bomber epoxy. great mechanical properties, especially in cold and wet conditions!

[sammer]

I have to agree with Pete.
West 206 will not give you enough working time and your epoxy will be gelling before you get it all layed up.
205 will cure fast enough and if you can add some heat to the mix will cure even faster.
West works pretty good, the only downside is the price.
My next epoxy purchase will probably be resin research composite pro,
http://www.resinresearch.net/id3.html

prices are pretty good and from what I've heard it's a really good product.
http://www.resinresearch.net/id6.html

And once again I'd would buy the slow hardener.

sam

[falls]

I've used the 205 fast hardener before with layup time about 1 hour for the first few pairs.
Pot life isn't that long (9-12 minutes), but thin film time (60-70 minutes at 70F) I think is adequate - especially if you mix small amounts as you go and wet out your glass on a separate table.
http://www.westsystem.com/ss/hardener-selection-guide/
206 definitely gives you more time, but you need to press for 10-15 hours.

[sammer]

Ya I got the numbers mixed up but still think the fast hardener doesn't give you enough time for your first builds. It's nice not to be panicked when you are trying to puzzle it all out.
I still like the slow hardeners, I'm never in a rush and generally press my skis overnight. (it's like waking up christmas morning never knowing whats under the tree)

And if you can add a bit of heat it cures fast enough.

sam

[MontuckyMadman]

I agree with falls. The 206 is a 15 hour cure, silly.
If you wet the fabric separately you have time till gel.
If you leave it in the pot yeah your gonna have a bad time.
separate batches.
If west is all you can get fine, but there are better epoxies for skis and compression molding for the same cost, some cheaper.

[falls]

still think the fast hardener doesn't give you enough time for your first builds. It's nice not to be panicked when you are trying to puzzle it all out

First few builds I think you mean it's nice to be LESS panicked trying to puzzle it out

[BRIDGER7]

it's hard to give you an exact number...read this thread and you'll see why: http://www.skibuilders.com/phpBB2/viewt ... e+laminate

Chrismp- Thanks for the reply and for directing me to thread.

[BRIDGER7]

For your first press, whatever, just pick a number. 50psi? Sure.

Yes you definitely want to leave it under pressure until it's cured.

Thanks again twizzstyle.

[BRIDGER7]

A good range is 45-55. If I press higher than that, I usually end up with texture of the glass showing through the topsheet. 45-50 is just about right for a perfectly flat top, adequate squeeze out, and properly bonded layers.
As Twizz said, leave under pressure until fully cured.
Have Fun!

Sherpa Burns- Thanks for the advice on PSI range, and for pointing out what can happen if you go too high.

[BRIDGER7]

I would recommend using the slow cure hardener (thats the 206, the fast is the 205). your pot life is pretty short with the fast cure, and the gel and working time with the fast is not long also. cure time on the slow cure depends on factors but it isnt too bad. its a safer bet to use the slow cure.

no need for using heat when using west systems. that epoxy works great at room temp of 70 degrees. i built a insulation box around my press thuogh to heat the ambiant temp to 90-100 degrees to speed things up. you can even press at temps lower than 70 degrees and then do a post cure out of the press. read about it on their website. great info there. west systems epoxy is a great resin system in my opinion

the slow cure epoxy doesnt take that long to cure under pressure. i usually leave my skis in for 24 hours. at 90 degrees which is excessive, but i figure the wood could use as much persuasion to bend and stay bent.

plan on 1 hour for your first layup (that is if everything goes well). i always use the slow hardener. i have even used the extra slow hardener, as a promotional/sample product from west systems.(they have great customer service!)

word of caution, dont mix up all the epoxy at once. (you might already know this) a larger volume will start to kick exponentially faster. I mix 12 ounces at once. One time i mixed 20 ounces and it starting kicking in the pot in about 5 min. Started exotherming and smoking. Bad news


go onto west systems website, there is an abundance of info, and it is one of the easiest epoxies to use. no heat required, and bomber epoxy. great mechanical properties, especially in cold and wet conditions!

petemorgan- thanks for the input on the 206 vs 205. We havent purchased hardener yet but I think we will use the slow hardener for now.

[BRIDGER7]

I have to agree with Pete.
West 206 will not give you enough working time and your epoxy will be gelling before you get it all layed up.
205 will cure fast enough and if you can add some heat to the mix will cure even faster.
West works pretty good, the only downside is the price.
My next epoxy purchase will probably be resin research composite pro,
http://www.resinresearch.net/id3.html

prices are pretty good and from what I've heard it's a really good product.
http://www.resinresearch.net/id6.html

And once again I'd would buy the slow hardener.

sam

Sammer- West is pricey, even with some shopping around online! Thanks for sending the link to the resinreseach site- per gallon, thats a whole lot better than West!