Glue help

[Chris333]

I need some tips to help get styrene to stick to cast metal. Putting styrene boiler bands on my MP 4-4-0's cast metal shell and it is pretty easy to knock the bands off. I used "thin" ACC.

Any ideas?  Would priming the shell first help at all? Is there magic glue?

[FrankCampagna]

Have you tried Walthers Goo? I believe that is the old school remedy for your problem. Haven't worked in metal in years, so I can't guarantee results.

Frank

[DKS]

My first pick would be a slightly thicker CA. If that fails, try Prism 401, which is considered one of the stronger forms of CA. Recommend getting the surface of the metal as smooth as possible for the tightest fit possible with the styrene. With CA, less is better.

My second pick would be Pliobond.

[Sokramiketes]

Super Glue is strong in tension but breaks free in shear.  I would use ACC to mount them, then drill a couple holes through the bands and glue in brass wire for pins.  Clip off and file smooth, and you'll have a mechanical joint to keep the bands from popping off at the slightest cross load. 

A contact type cement will work also, but requires a trip to the hobby shop if you don't have it already.   

[sizemore]

What about epoxy? It gives you some time to adjust before curing. I don't know what your handling methods are that is causing the bands to break free. I'd think with all the other free standing details that I know you'd add (handrails, walkways and tubes), it'd help in "protecting" the bands in some fashion.

The S.

[DKS]

Super Glue is strong in tension but breaks free in shear.  I would use ACC to mount them, then drill a couple holes through the bands and glue in brass wire for pins.  Clip off and file smooth, and you'll have a mechanical joint to keep the bands from popping off at the slightest cross load.

How much shear force would you expect to place on N scale boiler bands?

CA is a flaky adhesive. I've CAed small styrene parts to metal castings and had to slice them free with a knife; other times the parts have literally fallen apart in my hands, as if the CA was water.

I suspect that the metal and/or the styrene might have been contaminated with skin oils or such. Perhaps a quick cleaning with alcohol before bonding might improve things.

What about epoxy? It gives you some time to adjust before curing...

Epoxy is way too thick. It would be very difficult to apply a bead of epoxy cleanly enough for these small parts.

I'd offer another recommendation: make the bands out of brass, tack them in place with CA, and solder the ends together underneath. After soldering, re-apply CA (since heat breaks the bonds).

[Sokramiketes]

Super Glue is strong in tension but breaks free in shear.  I would use ACC to mount them, then drill a couple holes through the bands and glue in brass wire for pins.  Clip off and file smooth, and you'll have a mechanical joint to keep the bands from popping off at the slightest cross load.

How much shear force would you expect to place on N scale boiler bands?

CA is a flaky adhesive. I've CAed small styrene parts to metal castings and had to slice them free with a knife; other times the parts have literally fallen apart in my hands, as if the CA was water.

I suspect that the metal and/or the styrene might have been contaminated with skin oils or such. Perhaps a quick cleaning with alcohol before bonding might improve things.

What about epoxy? It gives you some time to adjust before curing...

Epoxy is way too thick. It would be very difficult to apply a bead of epoxy cleanly enough for these small parts.

I'd offer another recommendation: make the bands out of brass, tack them in place with CA, and solder the ends together underneath. After soldering, re-apply CA (since heat breaks the bonds).

How much shear? A lot?  Obviously enough to break loose the CA.  CA also likes some tooth, so a finely polished surface isn't going to help matters. 

Careful soldering something with CA nearby, those are some toxic fumes...

[DKS]

Super Glue is strong in tension but breaks free in shear.  I would use ACC to mount them, then drill a couple holes through the bands and glue in brass wire for pins.  Clip off and file smooth, and you'll have a mechanical joint to keep the bands from popping off at the slightest cross load.

How much shear force would you expect to place on N scale boiler bands?

CA is a flaky adhesive. I've CAed small styrene parts to metal castings and had to slice them free with a knife; other times the parts have literally fallen apart in my hands, as if the CA was water.

I suspect that the metal and/or the styrene might have been contaminated with skin oils or such. Perhaps a quick cleaning with alcohol before bonding might improve things.

What about epoxy? It gives you some time to adjust before curing...

Epoxy is way too thick. It would be very difficult to apply a bead of epoxy cleanly enough for these small parts.

I'd offer another recommendation: make the bands out of brass, tack them in place with CA, and solder the ends together underneath. After soldering, re-apply CA (since heat breaks the bonds).

How much shear? A lot?  Obviously enough to break loose the CA.  CA also likes some tooth, so a finely polished surface isn't going to help matters.  

Careful soldering something with CA nearby, those are some toxic fumes...

Sometimes CA likes tooth--the thicker varieties do for sure; sometimes it prefers very smooth surfaces--the thin variety likes as little airspace as possible. CA bonds by forming polymer chains. The less airspace, the faster and stronger the chains form. Thicker CA has inert material to aid the chain-forming in larger/irregular spaces.

If the fumes from heated CA were that toxic, I'd be dead many times over.

The fumes from CA are a vaporized form of the cyanoacrylate monomer that irritate sensitive membranes in the eyes, nose and throat. They are immediately polymerized by the moisture in the membranes and become inert.

[Chris333]

Maybe I can stick it on with Pilobond and lock it with ACC.  I can clean it with alcohol first.  My "handling" was while drilling holes for details, drilling holes in this stuff sucks, it is pretty gummy.

[sizemore]

Maybe I can stick it on with Pilobond and lock it with ACC.  I can clean it with alcohol first.  My "handling" was while drilling holes for details, drilling holes in this stuff sucks, it is pretty gummy.

How the heck are you drilling that material? Pot/white metal I think would be too "stiff" to drill anything less than a #60 hole.

The S.

[DKS]

Maybe I can stick it on with Pilobond and lock it with ACC.  I can clean it with alcohol first.  My "handling" was while drilling holes for details, drilling holes in this stuff sucks, it is pretty gummy.

How the heck are you drilling that material? Pot/white metal I think would be too "stiff" to drill anything less than a #60 hole.

It is a royal PITA, but it can be done. One of those patience-testing things.

Can you leave the bands until last, or near-last, to minimize handling them?

[Chris333]

It does suck drilling it. Every few turns you hear a little squeak and have to back out the bit and clean the gummed up metal out of it, then go back and do a few turns more...

The bands are back on as are the running boards (they are different than the photo) So now the running boards may help hold the bands on.  I need to drill for the sand lines, injector lines, handrails, Arrrrghhh.

[daniel_leavitt2000]

I get this sometimes with CA. It seems as if the metal would casue the glue to dry too fast, creating a weak link. Did you put the glue on the plastic or metal first?

[victor miranda]

mmmm tough job...
zamac  does not glue well.
If It was me....
I'd put a strip of styrene on the two ends
to keep the band for popping apart.
I guess another way to say this is that the  best way to keep the band
is to make it a continuous ,as styrene glues better than zamac...

superglue the band and plastic glue the band keeper.

v

[SkipGear]

Chris,
  I know you have it solved already but it you have issues again, look to see where the bond is breaking. More than likely, the glue is coming loose from the styrene, not the boiler. Make sure to clean the styrene also.

When you glue the bands, if possible, clamp/pin them in place, then add thin CA with needle or pin. Applying glue to the piece, then sticking it on with thin allows glue to start to flash before you install the part, weakening the bond. I use a glue bottle with a thin teflon capilary tube in it for pinpoint gluing. Using the tube puts enough glue on to make sure you get a good bond, then come back and clean up any excess with a file.