majortom-RCU

My Feedback: (40)

Anyone have a method for gluing up foam blocks, such that they can be wire cut through the glue joint? I need to make a canopy hatch that will require a bigger blank than I can cut from one piece of foam. The question is, how do I join two foam blocks with an adhesive that my hot wire will cut through without hanging up badly?

aeroman

I use Probond, and Gorilla to glue foam, I don´t think you will have problems cutting with your hot wire.

dicknadine

any good White or Yellow glue works real good. make sure that you hold the parts tightly together-pins, tape, rubber bands. no matter which glue you use, other wise they have a habit of slipping/sliding when your not looking. dick

majortom-RCU

My Feedback: (40)

Well, ya don't know until ya try. But as I suspected, nothing cuts with a hot wire like styrofoam except more styrofoam. The gorilla glue and the aliphatic both work fine as far as gluing the foam blocks together, but if you try to cut through the glue they both cause the hot wire to hang up, making for a very uneven cut. I found the gorilla glue hardens in about three hours. The aliphatic takes a long time to dry, compared to two pieces of wood. I think I'll use gorilla glue in the future.

What I learned from my experiment is, if you have to glue blocks together to get a big enough blank, try to figure out where the hot wire is going to pass through, and make sure you have no glue on that line. Both sides of the line will work, or only inside the line, but not on the cut-line. Then you can make a smooth cut.

One of my cuts was for hollowing out, so it doesn't matter having a rough cut there. The other was the outside surface, which I sanded down to remove the ridges. It's not exactly the shape I was after, but it'll work.

patternwannabee

My Feedback: (1)

How about using glue after the cut?

You could align the blocks with a couple of dowels bored through and just hold them together that way during the cutting, then glue them together using the dowels for alignment.

Just a thought.

Ed Smith

majortom-RCU is correct.

patternwannabee has the best solution.

I do a lot of foam cutting. I have never been able to cut through any glue line successfully.

Ed S

Mike James

Try puttiing the glue only on those parts of the blocks that you won't hot wire. It's not hard to figure out. Besides, you'll be glassing the blocks at the end anyway, right? So, don't worry if the glue doesn't extend all the way to the edges.

majortom-RCU

My Feedback: (40)

The last few posts are all pretty much on the mark. What I find is, it doesn't take a lot of glue over the entire interface, only a few spots at the corners and in the middle, and the blocks will not shift during the cutting process. After both the outside shaping cut and the inside hollowing cut have been made, it's pretty easy to glue up the pieces. Thanks for the input.

BN Models

Use polurethane glue.

rcmiket

What about 3M 77 thats how we did it on a couple of 130's we3 cut outta foam. -Mike

RAMFlyer

My Feedback: (65)

Use 3M's SUPER 77 Spray Adhesive. Note that is the SUPER version, not the everyday 77. A thin layer on both pieces is more than enough--most folks use too much. No problem cutting through the glue using nichrome, safety, stainless, or control line wire. Haven't tried MIG wire yet so can't speak from experience there.

Got this tip from Ivan Munninghoff who also wrote about it in his "Flying Models" column.

Bill