Ski Builders Forum

So no this:




Weird, since my rails after demolding are all like the above. I'm pressing on 50-60psi.

But now I've checked your photos I can see a slight "U" shape I think I see it.

I think you wil get that regardless due to surface tension.
Its no problem for snowboard construction as you need to sand it back anyway

Pressure doesn't pop the bubbles, it compresses them to a point where they're not visible any longer.

Or does it squeeze the air out of the pu all together?
Who really cares, it works.

ever seen anything like this when pouring your side walls? yikes!

Haha fun to watch though!

Btw, I recently built a board with a fir core (12% moisture content) and didn't seal the channel prior to pouring the sidewalls (no time). Still, the sidewall came out great with virtually no bubbles.

Haha that looks like trouble!

Been reading up on this process and I have a few questions.

1. Adiprene or Smooth on?

2. Urethane Rubber or Urethane Plastic?

3. Would it work to pour pu tip and tail spaces along with the sidewalls?

1. Depends on what is available. You can buy any brand of polyurethane as long as the properties suit your needs (shore hardness, cold temp resistance, pot life, etc.). I think I am the only one on this forum using Adiprene as the Smooth On stuff is more readily available.

2. Depends on your preferences. I am using a shore 90A hard rubber urethane (never tried a harder formula) and get good results. However, a harder urethane with hardness more similar to UHMWPE might give you better results.

3. Yes, you just need to router the channel accordingly.

Tip and tail spacers are deleted when using this method. You simply rout a trench around the entire perimeter of the board and fill with your favourite urethane.

gozaimaas wrote:Tip and tail spacers are deleted when using this method. You simply rout a trench around the entire perimeter of the board and fill with your favourite urethane.

No favorites yet still researching what kind will fit my skis best.

So I could fill the entire area that the tip spacer fits in , say 120mm x 200mm with the pu and it would work just fine? If so the see though tips and tails I'm going to make are going to be awesome.

Never tried it like this, but I don't see why it shouldn't work. If you plan on making such a long section with just PU, I'd recommend getting a harder formula (around 60 shore D) to avoid getting too soft tips.

As I see it the Smooth PU will get the moisture into the packaging soon after opening. Meaning goes off pretty soon (only part A, or B, don't remember:).

Hence doing a pre cured sidewalls. Using a pressure chamber as per Gozz suggestion. 50psi. Hard plastic. Impossible to imprint with a nail.

I've got PU rubber PMC 790, which interestingly is still fine, 4mnts after opening. It is soft, can imprint with a nail. See this:



Dropped my new board from about 30cm on concrete floor. PU is fine. FG slightly cracked. Nothing major.

This PU (310) is white.

This one:
http://www.smooth-on.com/index.php?cPath=5_1120_1156

is with red pigment:

Beautiful!

@ dbabicwa
The PU on both those boards is very nicely done! Impressive.

The boards are also very beautiful! Great work and thanks for sharing.

Can you please clarify. You said that the Red PU shown in the pictures is actually white 310 with red dye.

The link you posted however (http://www.smooth-on.com/index.php?cPath=5_1120_1156) takes me to these formulas that are clear, not white:

Crystal Clear® 202 - 90 min. cure time - for 1/16" - ½" thick castings
Crystal Clear® 200 - 16 hour cure time - for ½" - 3" thick castings
Crystal Clear® 204 - 48 hour cure time - for 3" - 6" thick castings
Crystal Clear® 206 - 5 day cure time - greater than 6" thick

Crystal Clear® 220 - MUST BE HEAT CURED - Click here to read CC220 Tech. Bulletin

Here is the link to the 310 : http://www.smooth-on.com/Urethane-Plast ... index.html

Is this correct?

Thanks!