Working with foam pannels.

Mark42

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Oct 8, 2003
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I am working with 1.5" pink rigid styrene insulation pannels (by Owens Corning) to make the hard top for my Bayliner. I know from other members posts that they have used the foam pannels to make insulated live wells, built in coolers, etc.

I have to glue up two to three 2' x 8' pannels to make pieces big enough to cut the top pieces out of. One problem I have been wrestling with is how to glue them together. The glue sold to install them (latex based) takes too long to dry (we're talking days here), especially when gluing two pieces together. Wood glue is not good, construction adhesive, contact cement, etc all melt the styrene.

Today I found a glue that really works great, not too expensive, is water proof, expands to fill gaps, doesn't melt the styrene, HARDENS IN 1 HOUR, and sticks to the foam really good. Gorilla Glue! Found it at Home Depot. Heard the name around for a few years, but never used it before, nor did I realize it foams up.

Gorilla Glue is much cheaper than epoxy, which is the only other glue that will bond the foam without melting it and hardens fairly quickly.

So if you have plans to work a project using styrene foam as the core, Gorilla glue is THE glue to use when building parts from foam.

I followed the directions and wet one side of the foam board with water (water just beads up), then smeared a thin layer of Gorilla Glue on the other, then pinned the two pieces together with tooth pics. The tooth pics were my idea, not in the directions. The glue starts to foam (looks like the foam that you mix for flotation) within a minute or two and squeezes out the cracks. Wait about 15 minutes to wipe off the excess foam or it will harden and leave big foamy lumps along the glue line. After an hour, its hardened enough for handling, cutting, etc.

BTW, if you decide to build a cooler, livewell, center console, etc from styrene foam pannels, remember that you must cover it with EPOXY and glass, not Poly and glass, as the poly will disolve the foam and it will ruin the project.

Attaching the pieces together I've cut so far has been a big holdup on the project. Today I bought more foam pannels (1.5" x 2' x 8' is $12) and tomorrow I start making the roof piece that requires 3 pannels to be glued up. I can't wait!
 

KnottyBuoyz

Senior Chief Petty Officer
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Mar 6, 2006
Messages
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Re: Working with foam pannels.

Can you post some pics of your project Mark? Keenly interested here. I've done some resin infusion of small parts using that foam for the core. One thing you have to watch for is stressing the parts after you've glassed them. The bond between the f/g & epoxy won't fail, the foam itself will fail. If you're putting a curve in the foam for your hard top, mold it first so you don't have to try to get it to conform to a curve after you've glassed it. Here's a piece I cut from a part I made and with just the vibration of the jig saw the foam failed.

foamcore004.jpg
 

Mark42

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Re: Working with foam pannels.

I remember those photos from last summer. Have to admit your experience has had a big impact on my construction methods to prevent separation.

There are 3 significant changes I'm making from original plan to compensate for separation.

1) The foam will be punctured about every 2" to a depth of about 1/2 to 3/4" using a small block of wood with nails driven through it. That should allow epoxy to sink in and get a better grip.

2) On large flat surfaces, a small hole, maybe 1/2 to 1" diameter will be drilled through the foam pannel and filled with an epoxy putty mix. This will give a solid connection point between the two sides of the foam. Sort of pegging the two sides together. I figure one of these holes on a 6" grid or so.

3) I plan on building up thickness by using glass matt between layers of cloth so the strength is in the glass and the foam is really a mold that ends up being encapsulated.

On the sides, even if separation occurs, there is not a big span before an edge is encountered. My theory is that the glass will be strong enough on its own in these areas and not really need much reinforcing.

The top is the big piece that will twist and flex. This is the piece that will need the "epoxy through plugs" to bond the two sides together.

Keep your fingers crossed.:D
 

Mark42

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Re: Working with foam pannels.

This is what I've done so far today. Taking a break because the heat and humidity is killing me...

The bottom of the hard top will have a wood strip incased all around where it touches the boat. T nuts are epoxied in place and holes drilled through the gunnel and plywood below so the top can be attached with bolts from below. I epoxied in the t nuts so they have less chance of breaking free.

Then the wood strips were glued to the foam side pannels using Gorilla Glue. See where the foam oozed out. Stuff set up so fast I couldn't wipe it all off.

Then I glued up 3 sheets of foam to cut the top pannel from. The foam has half lap edges so gluing up is fairly easy.

Notice the holes I drilled did not chip the gel coat. I just put masking tape down before drilling. All the other chip holes are from the factory running the screws from the glass frame into the gel. Every one chipped the gel.

Ph2008-06-0800068.jpg


Close up of T nuts with epoxy.

Ph2008-06-0800072.jpg


Gluing on the wood strips to the side pannels. The window openings are not cut out yet.
Ph2008-06-0800073.jpg


The three pannels glued together. Hard to see in the photo, but they are held together with tooth picks until the gorilla glue dries.

Ph2008-06-0800076.jpg


I'm going to get something to eat, then when it cools a bit, cut the roof section from that big pannel. It will be about 50" from front point to rear.
 

Mark42

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Re: Working with foam pannels.

Cut the top pannel out on the kitchen table. Just too darn humid to be crawling around on the deck on my hands and knees. This is your truly marking up the pannel getting it ready to cut.

Ph2008-06-08Bayliner00002.jpg


Here it is resting in place. The windshield divider is just scrap foam I placed there for reference of where the windshield center post will be.

Ph2008-06-08Bayliner00004.jpg


And from the aft...

Ph2008-06-08Bayliner00005.jpg


Yeah, it's going to be a flat top. For two reasons... 1) Its going to take a lot more work to bow the top. 2) I don't want this to drag on. I want to get it done, even if its a simple design.

That doesn't mean there won't be some interior bracing, and also a rib or two on the top side as well.

The roof pannel extends too far to the rear, so it will have about 6" or so cut off it. I just want a 2" extension past where the side pannels meet the top pannel.

A good day of solid boat work! Whoo Hoo!
 

Coors

Captain
Joined
Dec 8, 2006
Messages
3,367
Re: Working with foam pannels.

Taking a break because the heat and humidity is killing me...
Come down to Florida.
Good job. Never dealt with gorilla, it's always by the checkout lane, so I figured it was like super glue. Good for about 2 things.
 

Mark42

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Oct 8, 2003
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Re: Working with foam pannels.

Oh yea, I know how Florida can get. Lived there from Easter through August once. Boy summer was rough.

Gorilla glue seems to have all the properties of expanding foam. If you ever poured flotation foam or even used the expanding foam in a can for sealing up homes you know how sticky that stuff is. Gorilla seems to be just like that after it activates and starts to foam. Super glue is good for gluing fingers together... :D

But gorilla glue is not going to replace my wood glue or epoxy for hobby and basic home repairs.
 

Coors

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Dec 8, 2006
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Re: Working with foam pannels.

I'm gonna to get some and experiment.
 
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