The pouring urethane sidewall thread

For discussions related to ski/snowboard construction/design methods and techniques.

Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp

ben_mtl
Posts: 583
Joined: Mon Mar 31, 2008 1:47 pm
Location: Sherbrooke, Quebec
Contact:

Post by ben_mtl »

On the other hand it looks like the 790 only needs a flame ran over it after pouring to remove air bubbles while the 310/305 seems to require a more complicated setup (pressure chamber is a big NO for me, it scares the sh|t out of me !)

I have the 790 sample kit, will give it a try a see if I'm okay with the result... Meanwhile if someone finds out how to remove the bubble from the 310/305 without a pressure chamber I might consider it too !
A bad day skiing is always better than a good one at work...
User avatar
chrismp
Posts: 1443
Joined: Fri Feb 13, 2009 9:00 am
Location: Vienna, Austria

Post by chrismp »

Don't worry, 90A works very well! We've been using it for years now without any issue and so does Ride Snowboards ;)
User avatar
dbabicwa
Posts: 133
Joined: Tue Aug 28, 2012 5:16 pm
Location: Perth, Australia
Contact:

Post by dbabicwa »

Hm, flaming rubber = fire...

I've done a lot of experiments which you can see on my links.

See how 790 bonded with a bamboo:

http://www.youtube.com/watch?v=KiqOFrruUR0

You can cut 790 with a sharp knife. Impossible to do with 310. Are we talking smooth on products here? :))

Run some experiments first or risk to ruin your core (as I did).
ben_mtl
Posts: 583
Joined: Mon Mar 31, 2008 1:47 pm
Location: Sherbrooke, Quebec
Contact:

Post by ben_mtl »

My cores are not made out of bamboo, that should help :p
I'm not really worried about he 790 regarding how it bonds to my cores, Dtrain and other members had success using it. And yes they flame it (= pass a flame over the freshly poured PU) without any fire report... as far as I know...

You made a good point though regarding the softness of the product, I'll have to try and see how I like "rubberish" sidewalls. I can see some good aspects, as well as some bad ones but only a good test will tell ! I just watched a video about Rome's "slimewalls", it pretty much summarize what I think of PU rubber sidewalls : good point = damping and shock absorption, bad point = loss of "stiff edge" feeling...
The repair argument is irrelevant for me, bent edge = excuse for making new skis :)... I've never badly bent an edge though...
A bad day skiing is always better than a good one at work...
User avatar
chrismp
Posts: 1443
Joined: Fri Feb 13, 2009 9:00 am
Location: Vienna, Austria

Post by chrismp »

You can set UHMW on fire as well ;) Quickly passing a flame over the material does not burn or set it on fire in any way.

My statements are based on my expierence with pouring Adiprene LF950 PU resin into paulownia/beech cores. I've had no bonding issues whatsoever.
hallvardaase
Posts: 18
Joined: Wed Nov 17, 2010 11:27 pm
Location: Norway

Re: The pouring urethane sidewall thread

Post by hallvardaase »

gozaimaas wrote:I thought I would start this thread so that info on pouring urethane sidewalls can all be found in one place. If you pour your sidewalls please post up.

Ill start.
I used smooth-on product smooth-cast 305. It works very well and machines up easily. It is also quite hard and impact resistant. It cures in a bright white which is nice too.
I have put around 40 days on one of my boards and have had no issues at all. I even forgot to put vds rubber on that board and have experienced no delamination at all.

My biggest issue was bubbles forming as it cured so I built a pressure chamber and put the cores in that while they cure, this has solved the bubble problem.

Data sheet
http://www.smooth-on.com/tb/files/Smoot ... ___310.pdf

Anybody who got dealers to recommend for this, or other similar products?

Dealers in Europe, preferably..
User avatar
chrismp
Posts: 1443
Joined: Fri Feb 13, 2009 9:00 am
Location: Vienna, Austria

Post by chrismp »

www.kaupo.de are the only european distributor for smooth-on producats as far as I know. Their website is only in German, so you'll have to use google translate.
hallvardaase
Posts: 18
Joined: Wed Nov 17, 2010 11:27 pm
Location: Norway

Post by hallvardaase »

Thanks, Chrismp! :-)

I will probably order from them. Any opinions on which Product I should choose? I see that Gozaimaas is happy with 305.

I have a pair of half finished skis that I would like to try this on. The only problem is that the cores are already profiled.... Which got me to thinking that the "trough-method" for making epoxy sidewalls could work here. If it works it will reduce the amount of PU used. Another possible advantage is that you may be able to make the bubbles that may form appear in the part of the sidewall that is gonna be trimmed away when finishing the ski (Given that the bubbles rise to the top-layer of the poured PU, of course).

Has anyone tried this method? If so... any success or problems?

Link to "through-method":
http://www.skibuilders.com/howto/skicon/sidewalls.shtml
User avatar
chrismp
Posts: 1443
Joined: Fri Feb 13, 2009 9:00 am
Location: Vienna, Austria

Post by chrismp »

Sry, I haven't used smooth-on products, so I can't really give any recommendations. The 305 looks just fine.
gozaimaas
Posts: 663
Joined: Fri Feb 10, 2012 4:17 am
Location: Nagano Japan

Post by gozaimaas »

I toyed with the idea of trough sidewalls in the beginning but scrapped the idea and also scrapped the already profiled cores I had.
Imo you should just use a wood sidewall if you wish to save this core. If you want to use PU go to the trench method, its great.
ben_mtl
Posts: 583
Joined: Mon Mar 31, 2008 1:47 pm
Location: Sherbrooke, Quebec
Contact:

Post by ben_mtl »

Stupid idea/question (again...) regarding the bubbling problem with Smooth-On Smooth Cast 310 serie.

I'm not planning on using this product for now but have been thinking about the bubbling...
Gozaimaas mananged to get great results by making a pressure chamber. This (the pressure chamber) really scares me... but vaccum is OK ! What about taking a large sewer tube (8in dia might exist ?) and using it as a large degazing/curing chamber you would just slide your cores in ? would the result be similar ? would the PU cure under vacuum ?

Just throwing the idea...

Ben
A bad day skiing is always better than a good one at work...
gozaimaas
Posts: 663
Joined: Fri Feb 10, 2012 4:17 am
Location: Nagano Japan

Post by gozaimaas »

From my experience 14.7psi is not enough pressure to get perfect results so i doubt the vacuum could achieve it.
Smooth-on recommend 60psi for optimum results. I have settled on 40psi as it seems to get the job done.

A pressure chamber is nothing to be scared of as long as it is built correctly with bracing.
camhard
Posts: 125
Joined: Tue Dec 18, 2007 4:43 pm
Location: Vancouver, BC, Canada

Post by camhard »

Just wanted to post a quick note re: the urethane Dtrain sent my way.

It took a few experiments, but I'm pretty happy with where things are at. I did not really find that the moisture content of the wood reacted to cause excessive bubbling, as Dtrain did. Flaming is quite effective, primarily because it kicks the reaction into high gear. I found that mixing a large quantity in a small container (causing the mixture to heat up very quickly from the reaction) produced very nice results, though was unworkable. The foaming really seems to occur right at the end of the curing, and is made worse by a slower reaction.

Things were still very finicky (temperature changes in the room made a huge difference), until we setup a vacuum pot. This does not remove the need to flame (at least in my cold garage, where the reaction won't really go without some help), but makes a world of difference. The pot was made out of an 8" diameter piece of steel pipe, with end caps out of 1/2" ABS and 1/2" plexi with silicone filled channels. I'll post a picture soon, but just wanted to say that I am convinced the vacuum setup makes all the difference. You should see the amount of air that it pulls out; this stuff bubbles away like crazy for about 2-3 minutes!!!
Dtrain
Posts: 549
Joined: Wed May 18, 2011 12:03 pm
Location: Prince Rupert/Terrace B.C.

Post by Dtrain »

I also just got a vacum chamber rigged up. Keep me in the loop as I have a few gallons left of that stuff. And if I find I can get it to work smoothly would love to keep using it. Faster cure, clear, cheaper, harder. Glad you got it workin. With work and kids, I just did t have the time. Thanks for posting
User avatar
dbabicwa
Posts: 133
Joined: Tue Aug 28, 2012 5:16 pm
Location: Perth, Australia
Contact:

Post by dbabicwa »

camhard wrote:Just wanted to post a quick note re: the urethane Dtrain sent my way.


The pot was made out of an 8" diameter piece of steel pipe, with end caps out of 1/2" ABS and 1/2" plexi with silicone filled channels. I'll post a picture soon, but just wanted to say that I am convinced the vacuum setup makes all the difference. You should see the amount of air that it pulls out; this stuff bubbles away like crazy for about 2-3 minutes!!!

Yes, 17 minutes in a pot, full vac:



This is just a kitchen pot with a hole in metal lid. Cheap and fast vac chamber. Wear safety goggles tho:)

Pouring after 17mins of 20 mins put life might give some really good results. It worked for me.

Now thinking to go with goza method since 40psi is not really much.
Post Reply