Our first try.

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Sonny
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Joined: Sun Mar 11, 2012 12:09 pm
Location: Stockholm, Sweden

Post by Sonny »

We are currently not usng heat but that is definetly planned to be added soon.
Thef preassure in the 2 firehoses were 5,2 bar or 75 psi, but since they have some gap to fill they only had about 95mm contact surface each. But and since the ski are between 160 to 145 mm wide. So i guess the preassure at the skis would be close to 50 psi? Could it maybe be a combination of to little resin and maybe not enough preassure?
Amidnightproject
Ah yes of course thats the cattrack, i'll do what you suggested and put insome metal sheets there..[/b]
amidnightproject
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Post by amidnightproject »

How did you wet out the fiberglass (did you use a spreader, or a roller to apply the resin or some other method?). I'm with Twizz on this, it looks like your fiberglass wasn't wet out enough and possibly not enough pressure at the ski.

And do you have an idea what the room temp was at the time? Also, did you hot water bath your epoxy before you guys mixed and laid up.

And finally, how did you mix your resin?

Sorry for all the questions. :D
ben_mtl
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Post by ben_mtl »

I have the same thing happening on my skis : the fiberglass still shows a bit when I have a clear topsheet... I also noticed a few "dry" fibers when I bevel the edges of the topsheet after I cut the flash.

Here's how I work :
- my resin is stored at 27 deg C, I only take it out of the "temperature controlled closet" when it's time to add the hardener and use it.
- The temperature in my shop is only 16.5 deg C (when outside temp is below that)... radiant heating in the floor so I don't need more to be comfortable... maybe it's too cold as the triax is @16.5deg then... so the resin cools down and looses some "fluidity ?" when in contact with the fiberglass...
- I mix the resin with a mixer arm in a press drill
- I spread the resin in/on the fiberglass with a plastic spreader, not a paint brush or a roller

I suspect I don't get a good enough resin impregnation. The resin is pretty "thick" even at 27C and if I remember correctly when I used to use the West System Epoxy (very liquid) I had better soaking.
How would you improve it ? Could a "bubble remover roller" help ? Should I heat my layup table ? Should I just change my resin supplier and get something more liquid ?
... any idea would help !
Thanks !


For the first time I'll make skis in the summer (this upcoming summer), maybe I'll see some improvement with warmer temperatures...

Oh and by the way even with some dry fibers in my skis, the planks are holding strong... I'm not such a hardcore skier though.
A bad day skiing is always better than a good one at work...
Sonny
Posts: 43
Joined: Sun Mar 11, 2012 12:09 pm
Location: Stockholm, Sweden

Post by Sonny »

amidnightproject wrote:How did you wet out the fiberglass (did you use a spreader, or a roller to apply the resin or some other method?). I'm with Twizz on this, it looks like your fiberglass wasn't wet out enough and possibly not enough pressure at the ski.

And do you have an idea what the room temp was at the time? Also, did you hot water bath your epoxy before you guys mixed and laid up.

And finally, how did you mix your resin?

Sorry for all the questions. :D
Questions and help is very very welcome! :)

Our workshop is around 15-20'C when pressing, and the epoxy is stored in that temp also, maybe thats to cold? No heating of the epoxy what so ever. Anyhow, then we mixed it by hand in a round glass container, with a wooden stick, for a couple of minutes. Then we poured it into another bowl and mixed it some more. Then we poured it onto the skis, spread it with a plastic sheet and used a soft roller to wet out the fibers. At some spots we even used a aluminum roller to remove some air.

My friend also had some problems with air in his snowboard but i know for fact that he used a lot more epoxy since that was a lot being squished out when we put pressure on it..

What pressure do you guys have At the actual ski/snowboard?
twizzstyle
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Post by twizzstyle »

I press around 50psi in the hose. With the cattrack, and depending on the length and width of ski (I press one ski at a time) it comes out to maybe 60psi at the ski.
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vinman
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Post by vinman »

I had some thoughts of the dry glass/ air bubbles:

For Ben: could the drill mixer be inducing air bubbles into the epoxy? If so my suggestion would be to let your epoxy sit for a bit to le the bubbles rise and dissipate.

For everyone: are you overworking your epoxy? If you overwork your epoxy you can create a cloudy/foamy look to it. This is introducing air bubbles.

Other than that maybe a warm water bath to decrease viscosity and allow for butter wet out.

Ben, you might just see better results in the summer with warmer materials.....


For psi, I'm pressing at 50-60psi in the bladder. but I've never used clear top sheets to look for the air bubble problem either....
Fighting gravity on a daily basis
www.Whiteroomcustomskis.com
Richuk
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Post by Richuk »

For bubbles research 'voids' and 'de-gassing epoxy'.

Sonny/Ben - raising your epoxy to 30 degrees before consolidation should be enough to ensure the fibre wets out really well. I wouldn't go much above this temperature, a sleeping blanket under a spare thin sheet of AL should do this for you. If you head in this direction, you might as well consider whether applying the fibre to a film of epoxy is better than the traditional approach.

Sonny - great work btw!
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falls
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Post by falls »

laying the fibre on a film of epoxy rich? that works better? I guess I can see it.
Don't wait up, I'm off to kill Summer....
ben_mtl
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Post by ben_mtl »

Thanks for the replies guys !

Vinman -» yes the mixing does introduces quite some bubbles AND I might be overworking the epoxy a bit, sometimes I see the white/cloudy/foamy aspect you're talking about.

I'll see how it goes in the summer with warmer temps, I'lla also let the mixed resin sit for a couple minutes so the bubbles can dissipate !
The specs sheet of the resin states to store it between 20 and 30 degress C, I went with 27 and I'm OK with the viscosity, tried 30 degrees once and didn't noticed a big difference. I dont'want to store the resin too warm either (hence the few degrees below the max recommended temp).

One thing that should be good for me though is the fact that when temperature is applied to the resin (in the press for curing), if I remember correctly the rep told me that in the first minutes of the rising temp, the resin's visosity dicreases significantly. That would help with the wet out... or the squeeze out...

BTW I press @40PSI so I don't believe excessive pressure is a problem... but the 40PSI is applied on every square inch of the skis though... the fit is tight and the bladders remains pretty "flat" !

Thanks again
A bad day skiing is always better than a good one at work...
Sonny
Posts: 43
Joined: Sun Mar 11, 2012 12:09 pm
Location: Stockholm, Sweden

Post by Sonny »

Ok, so tomorrow I'm heading north. Finally i get to try the fruit of this project! for 10 days me and my girl will be skiing in the north of scandinavia and I'll be sure to post some awesome pictures :)

I am bringing two pair of skis since the ones I made are fitted with regular bindings and the other pair with touring bindings. If everything goes as planned and the weather is cooperating I'll be heliskiing with my own hand made skis on this friday. (GOD I like the feeling of my OWN skis) :)

Don't check back in this thread if you dislike nice nature pictures.
(google images for "skiing lofoten", thats where we are heading)

I'm am SOOOO excited! :D
twizzstyle
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Post by twizzstyle »

Sonny wrote:I'll be heliskiing with my own hand made skis on this friday.
The word "jealous" does not do justice here. That is AWESOME. Have a great/safe trip!
Sonny
Posts: 43
Joined: Sun Mar 11, 2012 12:09 pm
Location: Stockholm, Sweden

Post by Sonny »

So, we are back from the trip and I finally got to try my skis!

They were actually better then i would have dared to imagine, skied really well in chopped up powder, carved pretty alright in softer groomers and were a lot of fun and charged untracked powder like a beast! Love the length of the skis, (194cm) and the even with that somewhat extreme width they didn't feel too heavy..

This is definitely something to work with. I wish I have had the chance to let somebody neutral try them but unfortunately one of my heel bindings pulled out of the ski after a landing a drop, this happened the day before our heli skiing and I didn't remount them coz we were going home the next day..

I did shoot some video with my helmet cam, I'll definitely post that later so you get to see them in action! :)
Who's looking forward to winter 2013?!
I am!

The skis on snow!
Image

Girlfriend skiing down after a couple of hours hiking in northern norway.
Image
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