Ski Builders Forum

MontuckyMadman wrote:I think its too soft for sidewall material.
The edge will be able to deform to much.
You are essentially removing the main purpose of a sidewall, in my opinion, and making something softer for the edge to sit on.
When you hit something hard it will allow the edge to bend and dent.
Perhaps its edge cracking you are more concerned with?
Riding metal rails and not slamming into unseen rocks?
I want a super hard sidewall to prevent edge compressions, which will affect tunability and turnability on piste.

I wonder if you could add a fiberglass layer to the urethane during pour up?

The 780 formula I've been using is bonding great and is pretty damn tough.

Montucky, totally valid points. I think the strengths come in dampening and the small amount of flex in the sidewall provides some give over uneven surfaces(in the terrain park). Once layed up, with the rubber sitting inside of the glass it does have stable structure.

On impacts, that structure and bondability make it so that it can take the beating. There are some wakeboards that use urethane for park style riding and I've seen when the bash delams the whole laminate like your concern. Awesome thing was that it the sidewall was still in one piece and made an easy repair.

The finish on urethane isn't 100% yet. I've tried buffing. Wet sanding works the best so far. I added some urethane coating which works okay, but that is pretty temporary. Anyone know how to make this stuff shine after cutting out the flashing?

For the guys that are laying up a channel I found this vid from a kiteboard factory. Looks like they have an applicator that takes the bubbles out.

The standout to me is that they can machine it afterward.
My thickness with the shaped trough isnt' 100% and I can use a router to match the height. Now I'm thinking I an put this through the planer with their method.

http://vimeo.com/cabrinhakites/cabrinhaboardfactory

i've profiled all my cores with poured PU-sidewalls with my planer and will do the same with my CNC now. the PU machines nicely with regular wood cutting tools.

how does it sand?

doesn't sand very well, thats why i use a bench grinder.

i'm going to build a table that has a recess for the bench grinder to sit inside so the middle of the wheel is flush with the table. i will add small stop pieces next to the wheel on the table top to act as a guide for the edge of the boards so i can pass the board along the disc without grinding my edges.

the way i've been doing it until now was just doing multiple light passes until sparks started flying when the disc touches the edges.

i've been using a orbital drum sander to sand down until I see sparks. Seems to do better than my reichmann edge sander.

For getting the sidewall to shape I've been using a router. I'm seeing a change in texture toward the end of the pass because the blade heats up.

To finish I set up a jig on my base grinder and use a well worn 120 grit. This is giving me about 60% of the finish. Then I toyed with some clear polyurethane coating used on wood. I'm at about 80% of the result on the PMC 780.

The smooth-on 305 I used machines and sands perfectly, I am going to build a box so I can cure it under pressure to remove the air bubbles.

I am in the process of making another batch and found another way to reduce the amount of bubbles.

I've had luck hand mixing the material in the past, but I wasn't convinced that I was getting a complete mix. I attached a sponge brush to my drill and gave it a good mix.

Not such a hot idea. It introduced way too much air into mix. The slab had a gazillion small bubbles in it. I did my flame passing and that got rid of a lot, but there are still quite a few.

Moral here, hand mix that cocktail because less air gets into the mix, still flame or heat to pull the bubbles out. Should save you a few bucks.

This piece was a lifejacket that saved me from dwroinng.

A question for the boarders, I was wondering whether anyone had tried drilling laterally, into the core and filling with urethane - with a view to altering the lateral stiffness of the core.

hi builders
I have some questons about RUBBER urethane sidewalls..

I tested smooth-on plastic onyx (80 D) and it's really tough but it has broken as glass when bent
instead,the 305 (70D) it's quite better..
But uhmwpe it's another planet.....

never tested rubber but I'm fascinated about (not the urethane plastic) urethane rubber sidewalls because they can resist strong impact,it doesn't break when ultra bent and absorb much more vibrations than plastic materials.. what do you think about?
it could be the future?

And..on our boards we found stuff as slimewalls for ride, liquid ralis for liquid force, fusion sidewalls for slingshot and much more..
every factory declares they use urethane,but do you think they take ''the same'' stuff as smooth-on, mix a small quantity (one board per time) and pour it in the router channel?
Most of urethane requires post curing..factory wait for every single board after poured?!
I think exists a combination of quality-fast-durable material they use..

does anyone know about wich materials (wich brand and where to get it) is used in skate wheels contruction?

cheers

Ride does not pour channels . They get sidewall strips cut from sheets. They probably don't even cut them themselves. As it it being poured and post cured on a actual poly factory or machining centre, they could use anything as moisture sensitivity is not an issue when using the product properly.

As far as urethane rubber. Yes, it is the shit. But the only one working for me is has very thick viscosity and stinks right through my cartridge mask. I have tried tons of products.

Pouring in wood channels efficiently with great success is not easy. Goz has built a pressure chamber ( sure you've seen it) , if not search harder!

Yes you're right dtrain!
infact Iwas thinking how to make urethane sheets by myself..
and yes,probably is not so simple to get good quality (as factory standard) urethane sidewalls of rubber or plastic..
does the urethane rubber stinks so much?!?!
having a controlled environment probably makes the different.
I worked the urethane only with the pressure chamber,after I had disaster without
cheers

You mean this:

http://www.skibuilders.com/phpBB2/viewt ... highlight=

http://www.skibuilders.com/phpBB2/viewt ... highlight=

http://boardbuilders-forum.1077691.n5.n ... d1034.html