Foam sheet adhesive? (another glue thread!)

When building up sheets of pink or blue foam for a large nose cone or transition, what do folks use to bond the sheets together? Do you rely on bonding each sheet to the mandrel, or to each other or both?

ALso I assume you put a plywood plate across the bottom. Bonded with the same stuff?

And the mandrel? 1" dowel? Heavy duty motor mount tube (perhaps to be an electronics bay)? Any barbs, wires, or dowels through the foam for extra strength?

I was going to use laminating epoxy (System3, Raka) but realized I'd need a LOT of the stuff and thought I'd check to see if there is something better. Maybe beads of Liquid Nails or other caulk type product? Hot melt glue? Titebond? Duct tape? Cow Snot?

Finally, any suggestions other than the obvious fiberglass for covering large foam parts? Any one ever monokote them?

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow
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My experience is making wings for RC gliders. If you are going to hot wire cut the shape, use 3M77 spray contact cement. Almost anything else will make the wire hang. You may want to pull it apart after rough shaping with the wire and reglue with epoxy. If this is not an issue, I'd use the laminating epoxy but go easy on it so you don't have thick layers of epoxy that are significantly harder than the foam. This would make it harder to shape.

I'd lean towards fiberglass for the surface. That being said, it's the glass you want bonded to your aft bulkhead or shoulder because the glass is what is going to give your strength. The foam really is just there as a place to lay up the glass while it cures. Can you assemble a short length of body tube onto the forward end of a coupler tube (which becomes the shoulder of your NC) and insert the foam plug into that before glassing?

Larry

Bob Kaplow wrote:

Reply to
Larry W. Hardin

I have made some very large nose cones using this technique. For glue to bond the sheets together I have used 20-30 minute epoxy when in a hurry. If you have a lot of time Elmers white glue sets up just fine but can take up to a week to dry. I bond the sheets to each other, and those that touch the mandrel to it also. The Mandrel has always been a straight wooden dowel 1/2 inch for a 4 inch diameter nose cone and a 1 inch dowel for 12 inch diameter nose cone.

I use two plywood plates one the top (smaller dia) and one on the bottom (size of outer BT dia). I also have a center hole in the plates the same size as the mandrel dowel. This makes centering the plates easy. The two plates also make securing centering plates for turning easier.

The lathe for the large cones has been a vertical drill press with a bearing plate attached to the table or base as length required. Tool rest needs to be sturdy enough not to flex. Primary roughing of the shape is done with a hack saw blade. Final touches are with sandpaper.

Reply to
MarkU

3M Makes a spray can adhesive especially for foam insulation. It is Spray Insulation 78. It is available at the usual home improvement mega stores. It is made to adhere the foam insulation boards to other materials in construction but should work fine foam to foam. At least you know it won't attack the foam itself which can be a possibility with other adhesives.

nOrM

Reply to
Norman Dziedzic Jr

I guess it occured to me while reading the great responses here, could I just use some of the spray can foam as a foam adhesive? Spray some on one sheet like a bead of caulk, then slap it against the next sheet, and repeat for the stack. Any one ever try this?

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

Double stick carpet tape? Isn't that a bit high tech for trailer use? I thought they just nailed that stuff down, or let the sticky spilt beer spots act like glue! ;)

Joel. phx

Reply to
Joel Corwith

Another interesting idea!

In my case, the foam is an integral part of the rocket, not just the form. I may glass some or all of it, or may try Monokote or something like that. Test flights may be NEEKID! (did I mispel that right?)

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

Bob, amazingly I have found that plain old yellow or white glue does an incredible job of joining foam pieces together, the bond is stronger than the foam itself. However, this may not be suitable if you're planning to hotwire form the pieces afterwards. But if you're going to saw or cut with a blade, give it a try - it works great.

Reply to
BB

I have always heard (but never tried, so take it for what its worth) that the polyurethane adhesive (available at Home Depot in the tapes/glues section, so its probably available other places) is the glue to use for this. Its advantages would seem to be similar physical properties, so it can be worked either on a lathe, sander, or hot-wire cutter with equal ease. It seems to be really pricey, hoever, compared to the others, which is why I've never tried it.

Mark E. Hamilton NAR #48641-SR

Reply to
Mark Hamilton

nope, it's NEKID, only one E, with a variant of 2 Ks.

Anyway, hanging onto every word bob, as I am busy forming up a 2 foot, 8 inch cone using found 3 inch sheets of blue styro. right now i am holding it together with a length of allthread rod while i get the gross shape sanded out. yes it is for a level 2 and am doing my best to have it NOT look like an ordinary 3FNC but more flyable than the Grrr (no offense chris, I like your design)

Think i'll be using epoxy, as i'll be going to the big city (Minneapolis) next weekend with too little cash to buy what i want, but enough to get what i need. with a stop on the way back at a hamfest to get my technitians liscence

Reply to
tater schuld

I have also heard hot glue works, never tried it. It may melt the foam some, as long as it's not in the area being wired/shaped it wouldn't matter.

Kevin Patterson

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Reply to
TOOLS R US

kaplow snipped-for-privacy@encompasserve.org.TRABoD (Bob Kaplow) wrote in news: snipped-for-privacy@eisner.encompasserve.org:

Nekid, misspell, Brant, moot, Stine! Dang, the list just keeps growing!

BTW, a good adhesive for laminating foam parts, especially if you're going to turn it on a lathe afterwards is the spray foam in a can. Since it's the same harness as the foam you're gluing, you don't have to worry about rings forming at all the joints. And the stuff's way stickier than any glue!

Reply to
David W.

Well, now you'd better add 'harness' to your list:)

The problem I've had with the spray foam is that it needs exposure to air to dry, so the center section tends to remain goopy. You'd be better off with a low-expanding two-part foam (if there is such a beastie.)

Mark E. Hamilton NAR #48641-Sr

Reply to
Mark Hamilton

"tater schuld" wrote in news: snipped-for-privacy@corp.supernews.com:

Actually,it's NEKKID,as in Dave Barry's and Joe Bob Briggs usage of it.

Reply to
Jim Yanik

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