The pouring urethane sidewall thread

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

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

gozaimaas
Posts: 655
Joined: Fri Feb 10, 2012 4:17 am
Location: Nagano Japan

Post by gozaimaas » Tue Aug 19, 2014 6:08 pm

I use a 5/8 bit

switzch
Posts: 46
Joined: Wed Jan 05, 2011 7:35 pm

Post by switzch » Wed Aug 20, 2014 9:44 am

@ PMG - I have a few questions about this method. Bit unclear in my mind on how this is working exactly;

1/ My understanding is that you channel out one shape which is the same shape as the ski core plus width of the sidewall. The mold also has the same profile, but reversed. You clamp the profiled and shaped core up-side-down in the middle of the shape and pour the PU. Right?

2/ After you pour the PU and its cured, you thickness plane the top of the mold (bottom of core) removing any extra PU material. If this is the case I dont understand how you are getting the edge rabbeting? I can see that you use 0.8mm piece of white polystyrol but if you are pouring with the core upside down wouldn't the rabbet be on the top of the core? What am I missing?

3/ What are you spraying on the mold to ensure that the PU releases after cured?
winter is coming..

pmg
Posts: 435
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg » Thu Aug 21, 2014 3:12 pm

Hi switzch,

the core is not upside down in the mold. Bottom is on the bottom, top on top. That should untwist your thoughts :)

3) normal mold release which has to be removed completely after all this, otherwise it may harm bonding when pressing. So if using a mold release that stays liquid, the best is to seal the whole bottom of the core to prevent the wood sucking mold release.

pmg
Posts: 435
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg » Sun Sep 21, 2014 11:57 am

Have my first sample of poured Smooth On Task 12 here. The difference to 3xx series is huge: Its much more rubberlike regarding bending it. Offers less resistance to bending, but you can bend it like hell without it breaking.

I just took it out of the freezer, the low temperatures don't seem to bother the material at all - I do not have the smallest doubt this material won't break when used as sidewall. At room temperature, you can imprint it just a little bit with the fingernail, when its out of the freezer too, but the imprint is gone in seconds.

Will leave in in the freezer overnight, and then take a video of bending and hammering it.

pmg
Posts: 435
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg » Mon Sep 22, 2014 6:44 am

Ok,

a video of my Task 12 test piece, directly out of the freezer after being in there for 16 hours.
The video quality sucks, but you can see enough - especially me making a little hole in the kitchen working space :)

http://www.spame.de/skibau/task12test.MOV

Cheers
Philipp

User avatar
dbabicwa
Posts: 133
Joined: Tue Aug 28, 2012 5:16 pm
Location: Perth, Australia
Contact:

Post by dbabicwa » Tue Sep 23, 2014 10:02 pm

Hey gozaimaas

I''ve sent you an PM...Sorry, off topic.

D.

pavelbozak
Posts: 57
Joined: Tue Jun 10, 2014 6:18 am
Location: Europe

Post by pavelbozak » Wed Sep 24, 2014 3:15 am

pmg
PostPosted: Mon Sep 22, 2014 3:44 pm Post subject:
Ok,

a video of my Task 12 test piece, directly out of the freezer after being in there for 16 hours.
The video quality sucks, but you can see enough - especially me making a little hole in the kitchen working space :)

http://www.spame.de/skibau/task12test.MOV

Cheers
Philipp
scheiße !!! :)))))))

pmg
Posts: 435
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg » Wed Sep 24, 2014 8:45 am

pavelbozak wrote:
scheiße !!! :)))))))
Really forgot to put an extra board under it - thought of it but in my eagerness to see the result I forgot...

User avatar
dbabicwa
Posts: 133
Joined: Tue Aug 28, 2012 5:16 pm
Location: Perth, Australia
Contact:

Post by dbabicwa » Mon Sep 29, 2014 5:52 pm

What's the size of this *.mov file?

Or better, what's the verdict?

pmg
Posts: 435
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg » Sun Oct 05, 2014 7:17 am

The file is 96mb.

The verdict is that this stuff really is nearly undestroyable :)

User avatar
MontuckyMadman
Posts: 2389
Joined: Fri Jun 20, 2008 9:41 pm

Post by MontuckyMadman » Mon Oct 06, 2014 3:26 pm

but still deformable and thats the problem, 95 shore a isnt tough enough to prevent edge compressions and delaminations, and the uhmw is so much cheaper. The task 12 doesnt meet the durometer in my tests. I still cant find a liquid plastic or urethane with the elongation and hardness that the uhmw has.
The only one I have found in a polyether has a 2 min pot life at 150F, that sounds like it will be vary hard to work with.
sammer wrote: I'm still a tang on top guy.

sammer
Posts: 912
Joined: Wed Dec 19, 2007 10:37 pm
Location: Fernie B.C.
Contact:

Post by sammer » Mon Oct 06, 2014 9:36 pm

uhmwpe only has a shore hardness of around 65D from all the testing I can find.
Finding an equivalent shore to janka is almost impossible.
The only thing I could find was that ebony might have a shore equivalent of 90D.
That would lead me to think hard maple is probably only 50-60D, perhaps less.

I think there is more to this than just how hard the material is.
It has to recover from the impact and the speed of the recovery probably plays a significant roll.
A heavy impact between a rock and your edge (rockwell 50?) is going to deform your edge if not supported by a hard substance, but if both deform an equal amount your edge is probably hooped.
If the substrate can recover as the impact is removed maybe your edge will show less effect?
Your edge is hard enough it's not going to recover from a major hit.
If your substrate is hard enough to stop the deformation it will probably break away from the rest of the ski.
If the substrate is more elastic and recovers, can it absorb enough of the force to prevent major edge deformation?

I know there are technical terms for all this but I don't have that ring.
If I did I wouldn't be using the term "hooped" ;-)

Bottom line... don't huck cliffs onto rocks or I'm not going to warranty your ski!

sam
You don't even have a legit signature, nothing to reveal who you are and what you do...

Best of luck to you. (uneva)

User avatar
MontuckyMadman
Posts: 2389
Joined: Fri Jun 20, 2008 9:41 pm

Post by MontuckyMadman » Mon Oct 06, 2014 10:59 pm

The 95a urethane still alows the edge to deform and deform more than uhmw under the same load but the delam potential is much less with the urethane it would seem. Its a trade off. The wood explodes. Its hard but it flakes out after impact. Same you see with certain abs, cracks falls away slowly.
We dont aim for rocks but some years it would look like that.
sammer wrote: I'm still a tang on top guy.

gav wa
Posts: 375
Joined: Tue Feb 18, 2014 8:58 pm
Location: Perth

Post by gav wa » Tue Oct 07, 2014 5:01 am

I have heard board repairers say Ride Slimewalls (shore 95A) do have more edge breakages than other boards, but at the same time Ride boards have a great reputation and I haven't seen any complaints by people who own them, so who do you listen to. If they were inferior it would quickly become common knowledge.
I can say one thing though, Ride snowboards ride DAMP! I don't know if its all because of the 95A sidewalls but they are definitely one of the dampest rides going.

I've been using 65D polyurethane but have bought some 95A to try and have poured a swallowtail with it. But I put some milled glass fibre into the urethane to add a heap of strength to it.
Milled glass fibre adds tensile strength, flexural strength and impact strength.

If I was making boards for mass production and the retail market I would be more concerned with it all but making a few for me and my mates I'm not too as I know both styles of edge are being used by large companies and they both work.

bdankner
Posts: 3
Joined: Wed Feb 19, 2014 6:50 pm

Post by bdankner » Wed Nov 19, 2014 5:48 pm

I have a question for you guys who pour polyurethane sidewalls.
So I am currently using polyurethane sidewalls for the first time. I understand the process of what I am doing I just want to know about what actual polyurethane I should buy. I was also wondering if I could use the resin that I already have for lamination (I use super sap) and mix it with regular polyurethane so that I would not have to order special resin polyurethane online.
Thanks a bunch.

Post Reply