I have never used it myself, but have heard the PVA wood/craft glue works okay on foam, and would probably be the easiest to use on these large surfaces. Easy to spread without needing to rush. Would be easy to test.

All4,
I really like the Foam Tac, but spreading it would be a pain at this scale.

Harrow,
What brand would you recommend? A few hours ago, I put two scrap pieces together with the Elmers Wood glue. I just pulled them apart without any force. The surface area of the joint is/was 24 sq.in.

Had it dried properly? I'm guessing that stuck between two pieces of foam it has little exposure to air, and may therefore be slow to dry, possibly needing to be left overnight. You'd want to spread it thin to assist the drying, but I must say that this all just hypothesising and speculation on my part, as I have not tried it myself.

Foam safe CA should also work, but being exposed to CA over a large surface like that is going to burn your eyes and lungs out!

CA is brittle too. I wouldn't use it.

I added new pics to the fourth post.

I say go with the epoxy for the simple reason of the scale at which you are building. If you apply a thin coat to both mating sufraces it will hold fine. Plus you can buy in larger volume. If the weight of the glue prevents you from hovering, then you've got bigger issues to worry about.

Have you considered Great Stuff foam? It may not work on every application but should do well when building up layers. Verdon Weber uses it building his Star Cruisers, but he also laminates with fiberglass.

Originally Posted by crappie depot

I say go with the epoxy for the simple reason of the scale at which you are building. If you apply a thin coat to both mating sufraces it will hold fine. Plus you can buy in larger volume. If the weight of the glue prevents you from hovering, then you've got bigger issues to worry about.

Originally Posted by crappie depot

Have you considered Great Stuff foam? It may not work on every application but should do well when building up layers. Verdon Weber uses it building his Star Cruisers, but he also laminates with fiberglass.

I completely agree with what you are saying, but the weight of the epoxy is not the issue. The issue is the accumulated weight of all the little unnecessary weights.

Say you are building a 10 gram model, but slightly go over that because of the lack of consideration for all the unnecessary weight. You have an unnecessary 0.3g in the battery installation, an extra 0.2g in wiring, an extra 1g in glue, a messy solder job adds 0.2g, and you cut corners by getting a generic building material which weighs more than stated, which ends up being an extra 0.5g. That is an extra 2.2g resulting in a final weight of 12.2 grams. This is just a broad example, but it expresses my point.

For this reason, I am really liking the Great Stuff.

I got more work done, but very little due to my asthma. Refer to post #4. I picked up a potential sponsor on Friday.

I think I will go with Gorilla Glue. The stuff is strong, light, and does work on foam. I see iy as the median between epoxy and great stuff.

The only problem I see with Gorilla Glue is that it expands as it dries. You will need to make sure the pieces are pressed together hard during the drying process to prevent them from separating.

I'll get a bench press weight set from a friend. No separation will occur. I am also getting mixed opinions with the gorilla glue too.

I do not know what glue to use!!! Should I sacrifice some lightness and use epoxy? Should I dump a bunch of money into Foam Tac (Beacon)? Should/Can I trust Gorilla? I am going to home depot in a few so the decision will be made there.

Gorilla glue is polyurethane, isn't it? The stuff sets by being exposed to moisture, I believe. When doing a large area of foam, I have heard of people giving one of the sides a very light mist spray of water and then wiping it down, then applying the glue to the other side and bringing the two sides together. The remnant moisture on the sprayed and wiped side helps it set well. Don't trust what I just said, but do a little research and see if this is what you are meant to do.

Once it sets, I think it will be stronger than the foam it is attached too. Again, easy to do a test and convince yourself. In fact, I'd say a necessity considering the large size of the job you are about to undertake.

I have already tested and have confirmed that Gorilla is my choice. This stuff is strong and its expansive properties fill the little gaps in the foam which give the glue more grip area. You are right though about how the process is done.

How it is done:
1) make sure the surfaces are clean
2) wipe a damp cloth over one of the surfaces
3) apply glue to one surface and leave exposed for about 5-10 minutes
4) press and hold together

For step three, I will use a plastic taping knife (I'm using it as a squeegee) to spread the glue over the entire surface.
For step four, I am using weights from a bench press weightlifting set.

I laminated the outer spacers.