The pouring urethane sidewall thread

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gozaimaas
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Post by gozaimaas » Sat Apr 05, 2014 9:47 pm

Hey gav.
All smooth-on product in au comes through rowe trading who are the ones selling on ebay. ebay price is the same as the website so you might as well just use that.
Good luck with the wood chamber ;-)

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dbabicwa
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Post by dbabicwa » Thu Apr 17, 2014 8:21 am

^^^
What he said:)

the.quass
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Post by the.quass » Mon Apr 28, 2014 2:45 am

evening AU chaps. Is this the stuff on ebay? http://www.ebay.com.au/itm/Polyurethane ... 0799166100

I like in the video when it turns white. Pretty cool. Are you colouring it?
DC

gav wa
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Post by gav wa » Mon Apr 28, 2014 4:27 pm

thats the stuff. The other guys here have heaps more experience with it than me but 1 thing I will say is make sure you have wide mixing pots. Last time I mixed it in a 1 litre mixing pot and pot life was shortened by about 50%

gozaimaas
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Post by gozaimaas » Mon Apr 28, 2014 9:05 pm

I dont colour mine, I love the clean white look. Also I mix about 600ml total in a 1litre container without any dramas, plenty of pot life to pour and get my pressure chamber sealed up ;-)

gozaimaas
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Post by gozaimaas » Mon Apr 28, 2014 9:09 pm

White with veneer looks great IMO

Image

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dbabicwa
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Post by dbabicwa » Tue Apr 29, 2014 5:23 am

gav wa wrote:thats the stuff. The other guys here have heaps more experience with it than me but 1 thing I will say is make sure you have wide mixing pots. Last time I mixed it in a 1 litre mixing pot and pot life was shortened by about 50%
Are you making skis or boards or something else?

The white PU (325 I think) does not work with pigments, 327 does.

gav wa
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Post by gav wa » Tue Apr 29, 2014 5:44 am

dbabicwa - I'm making boards mate.

I only got a pot life of about 4 minutes before it started to thicken very quickly. My pot was about 4-5 inches across at the bottom and I mix by the weight recommended on the included instructions, measured on a very accurate set of digital scales.

I've checked out your blogs and those kite boards are very impressive.
One thing I was going to ask you though, considering you are premolding your edges, have you tried simply letting it cure at atmospheric pressure?
Without the moisture coming through from a wood core you shouldn't get any foaming. In the test batches I've done in plastic containers not a single sample has had any bubbles at all.
This is the reason I am going to try lightly sealing a channel with the same epoxy I'm using in the lay-up and seeing if after this dries smooth cast 305 doesn't bubble when hardened at atmospheric pressure.
Might not work but worth a try.

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dbabicwa
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Post by dbabicwa » Tue Apr 29, 2014 8:11 am

Thx Gav

305 I did not try, but like with any I think it expands first and than it shrinks. Quite a bit with both. That is the problem and a nightmare to clean after. At least for me.

With premoled if I could get the exact thickness every time (which I don't yet), placing and finishing edges would be really fast. Like a minute or two.

The idea is to have almost perfect size, ready to go when glassing. More and more I think the only way to achieve this is to machine the edges to the needed size. But how to, I do not know?!

D.

PS

And premolded mate, coz I use all PU in about 1 day after opening. Once you open it it will go off really fast...Even with Argon or Nitrogen on top.

Thx for the alu info as well.

gozaimaas
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Post by gozaimaas » Tue Apr 29, 2014 2:10 pm

Gav. I mix by volume, 1:1 and seem to get a longer pot life than you are. Maybe check yourwights and see if they work out to 1:1 by volume.
I have often experienced bubbles in the mixing container

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dbabicwa
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Post by dbabicwa » Fri May 02, 2014 5:37 am

The problem with a premolded edges is how to cut it for bonding together:

Image

The idea is to make a 45 degrees cut. Hm, not easy task tho...

Any ideas?

knightsofnii
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Post by knightsofnii » Fri May 02, 2014 11:53 am

looks like just another "skill" that you have to teach yourself..... get a real good knife or whatever, take a good educated guess, and go for it!
Doug

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dbabicwa
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Post by dbabicwa » Mon May 05, 2014 6:36 pm

gav wa wrote:dbabicwa - I'm making boards mate.
.
.
This is the reason I am going to try lightly sealing a channel with the same epoxy I'm using in the lay-up and seeing if after this dries smooth cast 305 doesn't bubble when hardened at atmospheric pressure.
Might not work but worth a try.
How did you go?

gav wa
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Post by gav wa » Mon May 05, 2014 8:13 pm

Sorry mate I have been busy working on building my heat mats. I will try it this weekend though.

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dbabicwa
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Post by dbabicwa » Mon May 05, 2014 9:45 pm

gav wa wrote:Sorry mate I have been busy working on building my heat mats. I will try it this weekend though.
I've just burned 2 3A fuses on 55-60C, luckily I've got them...

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