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Crazy glue, yes or gator glue from Kenny Loop.

 

Cyanoacetate (CA) is another name for crazy glue.  Cures with humidity which is backwards.  I would not by crazy glue as a brand name, find some hobby equals that are the right consistency.


Kenny Loop's glue is good for beginners as well because it does not cure quickly as CA.

Edited by Jonathan S
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CA works great for edge bonds. You might also some structure to an edge bond between brass and plastic or resin. For example, you might be able to drill a hole or cut a slot into the plastic or resin so you can mount the brass in the hole/slot before gluing. You can put the part into position and then apply glue using a CA glue applicator such as this or this.  A slot or hole also enables better alignment rather than just trying to get the brass to stand up by itself.

 

Use an acrylic glue, like Gator's Grip or Formula 560 Canopy Glue for surface bonds. The reason is that brass and plastic or resin have different thermal expansion properties. Acrylic glues remain flexible, so they will permit the materials to expand and contract at different rates without a bond failure. CA glue is rigid, to it won't flex and will cause shear forces to develop. As shear is CA's weakest bond strength property, it is likely to fail. You can apply these glues with a brush; clean the area around the bonded part with a brush dipped in water and let it set for 24 hours.

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I use clear gloss acrylic lacquer as an adhesive.  You can buy a giant spray can of it at most auto parts stores.  Decant a little into a cup of some sort.  Then apply the lacquer with a paint brush to the PE part where you would normally use CA. The lacquer takes a few minutes to dry so you can use it as an adhesive directly to the plastic, and have some work time to move the part.  If you mess up, be ready with some 91% isopropyl alcohol to clean up the plastic, and PE part.  Conversely, you can apply the lacquer to the plastic part then press the PE part to it.  It really depends on the parts used, and where they are on the model, as to which method will be better.

 

Alternatively, You can let the lacquer dry on the PE.  Once the lacquer dries, it basically becomes a layer of plastic.  Now you can use regular MEK type liquid cement to attach the PE part to the plastic part of your model. You can tack things in place this way and it makes a strong bond on its own.  However, once glued down with MEK, you can use very thin CA, along with capillary action, to wick an added bond with the CA. Just makes sure you let the lacquer and/or MEK dry for 24 hours before you apply the CA.  Otherwise you may seal the still soft lacquer/MEK under the part with no way for the volitols to escape.  Think of the CA as putting a microscopic layer of caulk around the PE part.  You want the Lacquer/MEK bond to have full strength before you apply the CA.  Now you have two strong bonds holding the part.

 

 I make my own CA applications out of a single 5 inch very thin piece of wire pulled out from the inside of a scrap electrical wire. The thinner the better.  Bend it around the end of a tooth pick or needle, then twist the two ends down to the tooth pick, then slide the loop off of the toothpick. The toothpick or needle can give you different diameter loops, depending on where you make the loop.  At the point, you can make a tiny loop, further down, you can make a larger loop. What you are trying to make is a tiny loop at the end of a stem.  Like a very tiny lollipop.  This loop and stem can be glued to a toothpick to act as a handle.  This tiny loop can be dipped into a drop of extra thin CA.  The loop is then just touched to the joint between the PE and plastic.  Capillary action pulls the CA along and under the joint to bond the two pieces.  I keep a tea candle burning within reach so that after each application, I can pass the loop through the flame to burn off any CA that may have cured on the loop.  The loop needs to be clean so that the capillary action works better.  Use small loops and don't try to apply too much at once.  Just wick some CA in there and let it cure.  Then if you need more, add more.  When you put some extra thin CA into a container to dip your loop into, only put in a few drops.  As that CA starts to dry in the container, it get thicker and loses some flow for the capillary action.  One or two drops at at time, and as many trips to the models as you can make in less that 3 or 4 minutes.  Then you need fresh CA.  I make a half dozen applicators at a time, and my loops are usually no more than 1/16" in diameter or less.  The repeated burning of the CA in the candle will weaken the wire and eventually it will break or crumble.  I also make a few applicator that are "U" shaped.  Make the loop as stated above then cut the loop oposite from the "handle" with a razor blade.  Carefully shape it into a narrow "U".  On some parts/joints, this works a little better.  

 

For larger flat PE parts, mask off the areas you don't want the lacquer on, and spray it directly onto the PE part.  Let it dry for about 30 minutes, then use the MEK and CA as described above.  Always rough up the PE part surface with a swipe or two of 600 grit sand paper. It helps the lacquer and CA "bite" onto the PE part.  If practical, it also helps to do the same on the plastic surface, if you can avoid sanding away any precious molded in detail.

 

The lacquer dries to the touch quickly, but I have found it really takes about 24 hours to dry between parts.  It is a "paint" product, and the volitols need to off-gas for it to fully harden.  When it is sandwiched between two parts, there is not a lot of space for the volitols to escape. So be patient.  On it's own, the lacquer makes a nice strong bond that is not as rigid as CA, and won't snap off as easily if the part has some side force applied to it.  However, I do recommend the combination of CA as described above.  If the model allows for it, meaning there is no risk of getting CA where you do not want it, then make a combination joint of lacquer and CA.

 

If you have any scrap model parts and leftover PE parts, practice with these first before going to your current project.  The applicators work great, but you need some practice to get the "feel' of the process and the qualities of the Acrylic lacquer.

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15 hours ago, Mstor said:

James, would this be the correct type of clear gloss acrylic lacquer spray?

 

https://www.homedepot.com/p/Rust-Oleum-Automotive-11-oz-Acrylic-Lacquer-Gloss-Clear-Spray-Paint-253366/205754650

 

I like your method and would like to try it.

It is acrylic lacquer so I am sure it will be fine.  I bought a can of Duplicolor brand clear at an auto parts store.  I was not looking for a specific brand, but just bought whatever was on the shelf.  

 

Definitely test it with some scrap to get a feel how strong the bond is.  It works to bond anything so scrap plastic to plastic will give you an idea of its strength.  Just don't use the MEK method or you may get an actual MEK type weld instead of the Acrylic lacquer bond.  Scrap PE  brass to plastic would be you best test.

 

Good luck, I hope it works as good for you as it does for me.

 

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7 hours ago, James B said:

It is acrylic lacquer so I am sure it will be fine.  I bought a can of Duplicolor brand clear at an auto parts store.  I was not looking for a specific brand, but just bought whatever was on the shelf.  

 

Definitely test it with some scrap to get a feel how strong the bond is.  It works to bond anything so scrap plastic to plastic will give you an idea of its strength.  Just don't use the MEK method or you may get an actual MEK type weld instead of the Acrylic lacquer bond.  Scrap PE  brass to plastic would be you best test.

 

Good luck, I hope it works as good for you as it does for me.

 

 

Thanks, attaching PE has been a pain in the arse forever. Always looking for new ways that may make it a little easier.

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