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Old 11-29-2011, 05:58 AM   #1
Zach

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Default Glass sheet layups. I want both sides class A finish!.

I am noodling on building some bulkheads for a boat that need to be finished on both sides.

I'm curious, as someone has bound to have come up with a smoother method of getting both sides of a laid up foam panel slick at the same time, without having to do a lot of priming, sanding and painting.

I am thinking about spraying gelcoat or a finish on the glass sheet, and then laying a layer of veil followed by 17 once biaxial cloth, foam, and another layer of cloth. Vacuum bagging it to the table.

When that kicks off, i'm thinking to turn the whole thing over and lay down a coat of gelcoat, veil, and wet out the face of the 17 ounce with thickened epoxy for any of the weave that may be exposed, and plop it down onto the veil. Vacuum bagging it to the table. I'm just not sure that the air between cloth and the veil will find its way out without voids under the gelcoat.

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Old 11-29-2011, 07:21 AM   #2
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metal sheets, polished. Either tool steel, or tool aluminum will work. You can polish it to a mirror finish, and will not shatter if you do something wrong (drop it, forget release, etc)
Might have issues with having bubbles find their way into the layers due to wet layup, and not having a good way to get sucked out. Might have to gelcoat the tools (top AND bottom) and infuse? They have cores that have channels in it for resin to flow, like distro media.
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Old 11-29-2011, 09:06 AM   #3
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Infusion between two panels will only work at very small parts or with integrated flow media.
Other method is wet layup on the one panel, the put some resin in the middle and on top the second panel. Than press it.
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Old 11-29-2011, 02:05 PM   #4
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RTM also works. I remember someone posted a light RTM video with a small boat being infused with positive pressure.
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Old 11-29-2011, 03:48 PM   #5
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LRTM is the only way to really create a "class A" surface on both sides of a single part, OP, you effectively need two moulds, a top and bottom which will press the laminate. I only know one way of doing it, we typically first create the female mould with about 10" of flange.

Once done, we lay sheet wax into the female mould and heat it very slightly to help with seaming the sheets together for a smooth finish, we lay surface coat (moulds are epoxy), 3 layers of thin glass (6 oz to 8.9 oz). You will also have to create on your female mould flange a groove to allow the vacuum seal to adhere too, we run two seams for this, one for positive and negative pressure (to the keep the resin in the mould and off the flanges).

I can PM you more details if you need more info, I am not 100% on what you are making, we always do this for auto parts which need exposure for both sides (hoods, trunks etc...)
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Old 11-30-2011, 06:04 AM   #6
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Carbonmods in the UK produce a lot of flat sheet, double sided gloss.

They sandwhich the wet layup between two layers of glass and use shims to aid with the correct depth of the flat panel.

With curvature I guess the only way would be a mould like press similar to what SLS and Dominik have said.
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Old 11-30-2011, 07:03 AM   #7
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I'm shooting for a 4x8 foot foam cored panel of varying thicknesses, to cut out and use as bulkheads (walls) on boats, to save from having to do the finish work on the panels in situ.

I appreciate the input. I had not thought about using two pieces of glass, one in the bag on top of the wet laminate too.

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Old 11-30-2011, 07:38 AM   #8
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Quote:
Originally Posted by DDCompound View Post
Infusion between two panels will only work at very small parts or with integrated flow media.
Other method is wet layup on the one panel, the put some resin in the middle and on top the second panel. Than press it.
did 24" x 24" with caul plate, and no media all the time last year. Sometimes with a layer of film in the middle of the stack. Was 24oz-100oz glass.
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Old 11-30-2011, 05:19 PM   #9
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Here is a good video from John Moore on LRTM of a Carbon/glass piece.

Here is another video from him showing a plaque.http://rtmcompositestv.com/video/plaque-mold-tutorial/

Home page http://www.rtmcomposites.com/ and store with supplies http://rtmcomposites.com/store/
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