Gluing brass to aluminum

[cp4449]

Off topic. My son is making a prop for a play. He is trying to glue rifle shells (brass) to a aluminum sheet for effect. welding is out, soldering does not work. Then he tried JB weld, they set up, but early come off if hit accidentally. Super glue and Gorilla glue tried also.

Suggesstions?

[Harold_V]

Keeping in mind that I have not attempted what I'm going to suggest, why not try applying some zinc based aluminum solder to the aluminum plate? It would be much like tinning with lead/tin solder. Once tinned, soft solder will then be able to be used.

Alternately, you might try replacing the aluminum piece with some galvanized steel, which will readily accept solder.

H

[Mr Ron]

Drill through the aluminum sheet and the base of the shell and use pop rivets.

[SteveR]

Which surface does the glue not stick to? That's a surface preparation problem. Removing oils and roughening the surface may help.

Or does the glue break? Then you need a stronger adhesive. Try a 2-part epoxy.

SteveR

[jcfx]

Props ( not propeller ) is my specialty, since that's what I do for a living.
Couple of questions followed by my comments -

How thick is the aluminum ?

Thin sheets especially if they're large are subject to flex, epoxies and super glues
are hard when cured so they'll pop off regardless of surface prep .

How clean were the brass carts and alu sheet ?

All metals have some surface contamination, be it oils or carbon in the case of shells if they've been fired.
As SteveR said cleaning and a slight abrasion will help.

How are the shells glued, side ways like they're laying on their side on a table or axially standing up like cylinders ?

Surface area is key here, if they were glued standing up with the open end down then you have a razor thin surface area
that makes contact, no glue will hold, filling the shell partially with glue and letting it set open end down on a flat hdpe
surface will make a larger surface area for the glue to do it's job. Note, partially filling the shells I would do with epoxy
not super glue.
If they're laying on it's side then it's a matter of building up a fillet so you increase the surface area.
Devcon makes a thickened epoxy glue but it's hard to come by, so I use Cabosil ( amorphous fumed silica ) to thicken epoxies.

Alternate ways to get the effect your son needs -

Silicone caulks are very good glues, and flexible, silicone would be of broadest use, one thing to keep in mind
is that there are two kinds, one that releases acetic acid on exposure to atmospheric humidity and one that
releases ammonia. It's the acetic acid releasing kind that he would want to use, it'll hold dissimilar materials
and I've used it to make temp repairs to silicone molds, as well as a paint.
Again, surface area is important, partially filling and fillets, depending on the orientation,
he can speed the cure a bit by lightly misting with water, naptha works well to brush out the fillets.

There may be spot corrosion where the metals meet the caulk.
That would require paint touch up in those areas, not a huge problem for a stage play, a little more so for TV or film.

Hope this helps
Jim

[jcfx]

Wanted to add one more thing, like HaroldV said if he can substitute a steel sheet then he can solder the shell casings
it's a matter of painting the steel sheet to look like aluminum.

[NP317]

Try hot melt glue.
Stupidly simple but has some flexibility and builds up well.
Sticky too.
RN

[cp4449]

Thanks gents. I will pass all of this on. The shells are glued on primer down.

[Bill Shields]

then drill a few little holes in the aluminum so that the 'glue' can push through the holes and have something to 'grab'.

assuming that the casings / primers are safe...open up the primer hole and stick a screw through it into the aluminum sheet...or a pop rivet as earlier suggested.