That would workSkierguy wrote:How about using either an 8" or 10" dia. PVC pipe for a single ski's pressure chamber? It should give you enough more than enough space to make a small shelf within the pipe to place the core level. An 8” pipe should give you at least 7 ½” of usable width and a 10” pipe 9 ½” (Assuming 1 ½” tall working space)
One side with a glued cap and the other a threaded cap you should be able to slide the core in and thread the cap onto the pipe with plenty of time to pump the chamber up to pressure. Assuming you used schedule 40 pipe, it has a max pressure of 160 psi (water).
The pouring urethane sidewall thread
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Works in theory but I think in real life it would be too complicated. All your lines/hoses would be throw aways every time too.Richuk wrote:Would it be possible to sandwich a piece of plastic (none stick) between two cores. Place the stack in the press, pressurise and pump the urethane in under pressure?
The urethane would be in a pressurised pot, open the tap and the fluid runs in. The pressured bead would flow around a circuit. The compromise would be a 2mm section - a dividing wall, so that the bead of urethane flowed from point A to point B, passes through the plastic into the top layer (second core) and exit via the bleeder hole. Both cores would have this 2mm compromise.
Thinking there would need to be a thin none stick film - polyprop, silicon paper etc, between the core and the plastic or hardboard or whatever. When it come out of the press, peel back the film
After fixing all the leaks in my plywood pressure box I pumped it up with 30 psi and it made noises like an old ship at sea, then bang. It was time to move on lol
So I built this from 3.0mm aluminium sheet
And braced it up with 50x50x2.5 steel angle to "stop" it from flexing too much. The angle failed at 40psi but the box survived
So I stepped it up with 50x25x2.5 rectangle tube
Problem solved, the results speak for themselves. No bubbles at all and a really nice finish. This is at just 35 psi.
So I built this from 3.0mm aluminium sheet
And braced it up with 50x50x2.5 steel angle to "stop" it from flexing too much. The angle failed at 40psi but the box survived
So I stepped it up with 50x25x2.5 rectangle tube
Problem solved, the results speak for themselves. No bubbles at all and a really nice finish. This is at just 35 psi.
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305 has 30 mins pot time?
This is your enemy. Use a fast one like 325 I think.
I am using 310 atm and this is the result after degassing for 17min and than pouring ( 18-20 mins pot life):
The degassed one is on right side. In the middle is non degassed one.
On the bottom is foamed example (wet bamboo). In overall 4 experiments.
Look at here:
http://boardbuilders-forum.1077691.n5.n ... 34i20.html
This is your enemy. Use a fast one like 325 I think.
I am using 310 atm and this is the result after degassing for 17min and than pouring ( 18-20 mins pot life):
The degassed one is on right side. In the middle is non degassed one.
On the bottom is foamed example (wet bamboo). In overall 4 experiments.
Look at here:
http://boardbuilders-forum.1077691.n5.n ... 34i20.html
Yeah I started with 305 pouring at atmospheric pressure. It worked ok but definately had bubbles in it, the bubbles seemed to form right at the end as it went off and the temperature increased.
I dont seal the wood, I feel its best to let the urethane bond to the wood instead of having a possible shear layer in between.
If you can do it, definately make a pressure chamber like mine, it will change your life haha
I dont seal the wood, I feel its best to let the urethane bond to the wood instead of having a possible shear layer in between.
If you can do it, definately make a pressure chamber like mine, it will change your life haha
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@dbabicwa: thanks for sharing your findings! We always degas the resin and hardener seperately before mixing them...this also reduces the amount of bubbles. How did you seal the channels in your samples?
@gozaimaas: that aluminum box looks like a great idea! Any info on its construction would be much appreciated (especially how you load the cores into it and how it's sealed)!
@gozaimaas: that aluminum box looks like a great idea! Any info on its construction would be much appreciated (especially how you load the cores into it and how it's sealed)!
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