Vacuum Bagging - will this work?

[Surfdad]

I posted a similar thread on WW, but I normally get more informed responses here TO's rock!

I'm "almost" ready to start expiermentation on a vacuum bagged board. The way that I will be doing it, is rather than tuck the whole project in a bag and pull the vacuum, I'll be using a rocker table and bagging the project down to the table. There will be a film over the top and sealant tape around the edges that the bagging film will seal too. VERY similar to using cling wrap around the top of a bowl, except then I evacuate the air inside.

On boards that I have seen that are obviously bagged, the rails are hard and there is no tuck. That is the very edge of the rail and the bottom are the furthest projection. Just to give a quick visual, this is what a cross-section would look like.

Do NOT give me grief on my artistic abilities! I know I suck at it!

As you can see, the bottom edge of the rail is what sticks out the furthest.

[Surfdad]

However, if I want a slightly tucked rail, where the bottom edge of the rail is tucked under and the furthest projection is further up, I don't think that the bagging film will pull in to that "void". I'm planning on using 1 # EPS for the core material, so I can't pull a vacuum of more than 8 inches of mercury. At such a low vacuum, I think the film won't pull tight to the tucked part of the rail.

So, here is my idea. I will use a high density foam (divinycell cell h-80 5 pound density) for the rails and shape them appropriately. I will use the aforementioned 1 # density EPS for the main core. Then, to force the fabric to adhere to the tuck, I will use a lighter density foam that the rails can crush at vacuum. So, if I use a 0.5 pound density foam, I can adjust the vacuum such that the core 1 # foam intergity remains, but the 0.5 # foam is crushed.

Theoretically, I think that works. V Bagging experts or engineers see holes in the theory?

A "simplistic" representation, I will use release film and breather in appropriate locations:

[yearroundboarder]

What is your laminate schedule? Are you using molding mat or some type of double bias knit/mat combo? There are a variety of options for infusion out there these days; even some very good 100% glass options without flow media.

[Surfdad]

Hey yearround,

Here is my "plan" if you will. My first test panels will be with some left over 4 oz E-glass. 1 bottom, 2 top...to cut my teeth. Then up to S-glass same schedule. I eventually hope to build a composite sandwich that will look like this:

glass/balsa/glass/EPS Core/glass/balsa/glass

I no doubt will use a d-cell rail, or possibly balsa.

I couldn't figure out how to do infusion with the composite without saturating the balsa or scoring the really light eps core such that I worried about the integrity of the final product.

I've had a couple of folks say that, if I have a minimal laminate schedule - possibly bottom layer first and then the two top layers that I can get the soft rails bagged so long as I watch the film doesn't get wrinkled.

Sound reasonable?