CPT 2010/2011

Document your personal work here. Show photos, movies, and share your secrets.

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COsurfer
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Post by COsurfer »

Brazen, dont be a dick. Doughboy provides a LOT of valuable info on this forum! I cant say the same for you.
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Brazen
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Post by Brazen »

I see, correct me if I'm wrong, but IM THE ONLY ONE HERE WHO OFFERED A VIABLE SOLUTION ...where's YOUR "valuable information"? DBS has a reprehensible habit of mouthing off in peoples threads for no apparent reason other than turning them into dick measuring contests, and by coming to his defense you're not far behind. Eirick, sorry about your thread, your skis are beautiful.

http://www.epotek.com/SSCDocs/techtips/Tech Tip 4 - Removing Bubbles.pdf

And from another site:

3. THOROUGH mixing is the most important part of this procedure. Even if you have experience with other types of resins, it is very easy to underestimate the amount of mixing this product requires. Depending on the quantity being mixed, it can take anywhere from 3 to 7 minutes of continuous mixing without whipping. During mixing the product will turn cloudy white and you must continue to mix until all signs of haziness and white streaks in the mixture have turned back to a completely transparent color.
4. Do not whip this product while mixing. Excessive whipping will add a tremendous amount of air bubbles which are difficult to remove.

But, by all means listen to DBS, he's "personally built thousands of boards mixing the epoxy with a drill and have not ever had a single air bubble." I doubt it.

"The guys that are building tens of thousands of boards do not mix their epoxy by hand, and they do not slowly ramp up their heat"
My point exactly. I will continue to do things the right way, because that's the beauty of quality vs. quantity.

Screw up on this 3====> :D
"86% of the time it works 100% of the time".
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tufty
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Post by tufty »

Mixing with a drill doesn't imply "turn the dial to 11 and hit the go button". Like a food mixer that you can use for mixing dough or beating eggs, most drills have a variable speed. Obviously, the mixing has to be done with care, or you end up with beaten eggs rather than epoxy, but you get a better mix with significantly less effort using a mechanical mixer than mixing by hand.

This doesn't necessarily apply if you're mixing up tiny quantities of epoxy, but for enough to do a pair of skis or a board, mechanical mixing done properly is more likely to provide a correct mix. This doesn't mean that hand mixing is necessarily worse, and obviously your results mixing by hand are looking good, but it's work for nothing. Why walk when you have a horse, and all that.

With regards to press heating, I don't know directly, but I do know that Rossignol / Dynastar don't bother ramping up the heat when they are making their protos or race skis. That said, their process overall is totally nailed; it may be that ramping up the heat is a good idea if you're throwing bubbly epoxy into your layup.
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MontuckyMadman
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Post by MontuckyMadman »

Vacume degas
sammer wrote: I'm still a tang on top guy.
Eirik Hanes
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Post by Eirik Hanes »

thanks for the replies...

We are not using heat blankets yet, just regular fan heaters. So we are definitely ramping the temperature up slowly. To about 40 C.

We did try to squeeze out the bubbles after putting the topsheet on, but it did'nt seem to help much.

seems like heating the epoxy slightly after mixing is the easiest for us, thanks for the link. Will heating the epoxy before mixing make less air bubbles in the mixture while mixing?

Also I found this paper on Polyurethane adhesive:
http://www.adhesivestoolkit.com/Docu-Da ... C(A)23.pdf

Looking at figure 1 page 6, it sems that this polyurethane compound (3m dp 609 ) goes towards a glassy state at 0 C. As the author writes: "At the lowest temperature 0 °C the adhesive is approaching a glassy state. The modulus has increased significantly whilst the strain to failure has decreased"

After reading this paper, I would like to see how the curves for the epoxy i am using are! And, we are using polyurethane to glue steel edges and sidewall, maybe its not such a good idea after all?
OAC
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Post by OAC »

What epoxi are you using?
Eirik Hanes
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Post by Eirik Hanes »

Araldite ESR3/ESH3
skidesmond
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Post by skidesmond »

Eirik Hanes wrote:thanks for the replies...

We are not using heat blankets yet, just regular fan heaters. So we are definitely ramping the temperature up slowly. To about 40 C.

We did try to squeeze out the bubbles after putting the topsheet on, but it did'nt seem to help much.

seems like heating the epoxy slightly after mixing is the easiest for us, thanks for the link. Will heating the epoxy before mixing make less air bubbles in the mixture while mixing?

Also I found this paper on Polyurethane adhesive:
http://www.adhesivestoolkit.com/Docu-Da ... C(A)23.pdf

Looking at figure 1 page 6, it sems that this polyurethane compound (3m dp 609 ) goes towards a glassy state at 0 C. As the author writes: "At the lowest temperature 0 °C the adhesive is approaching a glassy state. The modulus has increased significantly whilst the strain to failure has decreased"

After reading this paper, I would like to see how the curves for the epoxy i am using are! And, we are using polyurethane to glue steel edges and sidewall, maybe its not such a good idea after all?
Good article. Wonder if improvements have been made since then it was originally published. The site has a lot of good stuff.
Richuk
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Post by Richuk »

A guard over the cutter would be good - just sayin'

You can reduce the impact of the drawing pins using matchsticks. Quicker.

Abandoned topsheet - did wonder whether adding a bit more epoxy would have helped. Bubbles need a layer of epoxy to move through otherwise they will be held by the pressure. The pressure being applied by from above isn't necessarily applied evenly - even with a good cat track.

What is your heat treatment process?
Eirik Hanes
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Post by Eirik Hanes »

Hey Rich, we just use a simple propane/butane torch. We use the purple part of the flame, which is the hotest part (secondary combustion), and supposed to give the highest bombardment of the surface. -> increase the surface energy. The speed which we move the torch is about like walking speed.

Image

Purple part just at the end of the blue.

I read a paper about this topic, but i could not find it again. I'll post it if I find it.
Richuk
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Post by Richuk »

Something like this:
http://www.tappi.org/content/enewslette ... 2Grant.pdf

This adds something:

http://www.skibuilders.com/phpBB2/viewt ... nt&start=0

As does this:

http://www.skibuilders.com/phpBB2/viewt ... +treatment

Dyne pens or inks looks like a good step forward, until you get the 'art' of this process nailed.
mpm32
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Post by mpm32 »

You could pull a vacuum on the mixed epoxy to degas it.

You could diy a pressure pot pretty easily and it will pull all of the bubbles out.

Mix it mechanically all you want, throw it into the vacuum and then you'll have some bubble free resin. (Keeping in mind pot life of course)
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