Polyurethane Rails attempt - SUCCESS!

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Re: So, who want's PU rails?

downunder
Hey Matt,

this a recommendations from Smooth-on:

http://www.smooth-on.com/tb/files/Smooth-Cast_320,_321,_322.pdf

"For Best Results . . . Best results are obtained using a pressure casting technique.
After pouring the mixed compound, the entire casting assembly (mold, dam
structure, etc.) is placed in a pressure chamber and subjected to 60 PSI (4.2 kg/
cm2) air pressure for the full cure time of the material.

Post Cure - Castings will reach “full cure” faster and achieve maximum physical
properties if post cured. Allow material to cure for recommended cure time at
room temperature followed by 4 - 6 hours at 150°F/65°C. Allow casting to
come to room temperature before handling."

There should be no bubbles at all.

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Re: So, who want's PU rails?

downunder
This post was updated on .

Big success!


BIG!


It looks like a factory or industrial made piece of plastic. Absolutely no air bubbles. Smooth as.

There are actually no word to describe my happiness ! Happy, happy, happy!
 




The aluminium mold was inserted in a pressure chamber on 60psi for 2 hrs. Than taken out. The mold itself is bigger than 1/4" (inside measurements) the exact size is 10x10mm (outside measured), "U" profile, 3m long. The cost is about 15$.
Because it's bigger I've found some thick double sided tape which I've placed inside of "U" profile  to get inside measurements of about 6mm in width. This proved to be just about right.

This is my first pre made rail with exact measurements for the core channel:



And here I am inserting a rails in the channel just to test how it goes:



You can see how shiny this rail is!

I will order now a professionally made mold for 4 rails which makes 2 boards. Than if that goes well, I'll get a second one to get as many rails I can make with 1kg batch of PU just after opening.

1kg (900g), is the minimum order. Once is opened it will start loosing properties and will foam soon.

Today at the same time I've poured PU in two of my other cores. They bubbled as.  Had no choice since the channel was tapered before. I do not think will taper it again, too much work.

So for me, this chapter is closed!

Might have some pre made rails for sale:) 1/4" or 6mm by 6mm, 1.7m in length. So 2 peaces for one board, each with different flouro colors, or other colors...

Pre order now if you like the colors I've got on this thread. Priced to recover a PU cost and a postage. How's that? Just for your testing for like one board.

Oh, yes, and I'll have a surprise this time with my boards. Something never ever done before, on my knowledge.

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Re: So, who want's PU rails?

downunder
This post was updated on .
A couple of tests.

As SmoothOn PU is getting a momentum in a snowboard building as well, I decided to put some in a freezer and smash it with a hammer:)



The hammer weight is  1190g, I hit the sample from about 15cm with the hammer edge:



Then hit it from about 30-40cm with a hammer head:



Repeat the above after the sample was on Sun for about 20min:






Not  a scientific research but do not see any significant difference...

But this is interesting, when I bend it it does not break! Not frozen sample breaks. Hm...

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Re: So, who want's PU rails?

downunder
More tests.

Pre cured PU on 50psi, in a freezer for 12h, sample size 6.12x7.4mm:

Hammer edge hit from 10-15cm:





Bent sample, clear break:



Bent sample not frozen - at this angle the frozen part snapped:

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Re: So, who want's PU rails?

downunder
This post was updated on .
The PU PMC 790 test:

Hammer test, no visible dents:



The finger nail imprint:



Bend test from a freezer:



No air bubbles, some unknown marks, almost transparent:



Hope this helps someone.

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Re: So, who want's PU rails?

downunder
I hope you can see my new pre-made rails:)





Oh yes, they do glow in a dark when charged! In colors too:)

Now, an awesome idea: embed an LED diode and bingo! Hm, shall I or not?!
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Re: So, who want's PU rails?

Chris
Looking good :)

Howabout trying something like this:
http://youtu.be/8vsB1tsKkx4

???
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Re: So, who want's PU rails?

downunder
Thx, something like that:)

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Re: So, who want's PU rails?

downunder
This post was updated on .
My new batch:



Nice flouro colors:)


The only thing is and I do not know why, half of rails end up thinner on one side only! The mold is in a pressurized plastic pipe which is in level (well my level is 30cm long so crap). But still. Why half and not ?!

Is the mold or a pipe distorting somehow on 60psi pressure? But it is level, I've checked many times.

Or shall I make a higher rails and cut it (a planner?) somehow latter? Or get a big level to check!
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Re: So, who want's PU rails?

downunder
All done!

1.8kg (part A+B) of PU can make nice 16 colored rails 6x~5x1700mm






Not bad.
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Re: So, who want's PU rails?

downunder
This post was updated on .
Bonding rails with a cut on ~45 degrees:



This shouldn't be a problem, right?! Argghhh

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