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Gluing or Welding broken plastic on apple computers/accessories

I have a lot of old Apple/Macintosh equipment with a lot of broken plastic tabs. Is there any reliable method for gluing/welding model pieces? Any particular glue that bonds really well with the plastic? I'd love to learn about experiences from others. For myself, I can say that Testors brand model glue seems to barely bond at all, it looks nice until you try to flex the joint at all. Thanks for the input!

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You need some sort of super-strong, thin cyanoacrylate that will literally melt both pieces into each other. Every hardware store will sell that. Testors is made for styrene plastic specifically: it will melt and make a rock-hard bone on that, but not what Mac cases are made from.

 
Cyanoacrylate is the stuff of superglue, it doesn't do a chemical weld, it doesn't even dry. It cures by pulling a bit of water vapor out of the atmosphere which begins a self-sustaining polymerization process as I understand it. That's why a few individual drops work far better than one big glob, more surface area makes for better curing. It's a really neat exothermic reaction. I discovered its reactivity with some fibers when I set the end of my shoelace on fire with it. [}:)]

For ABS plastics you want to use an ABS cement formulation which will weld the parts together. It's mostly MEK with some acetone and ABS in solution. Our resident research chemist, Paralel will hopefully be teaming up with a materials science guy he knows to come up with a proper formulation for Macintosh Cement. Using pure Acetone for repairs isn't really what you want to do, no matter what "information" you see floating around on the web.

In the meantime: IIRC OATEY sells ABS Cement in Black, White and Yellow. I've only seen black on the shelves of the Big Boxes because that's the color of ABS pipe and fittings. Eventually I'll order a few cans of white and one of yellow online to try to come up a color formulations for Beige, Platinum and the PowerBook colors. The other option I'll be trying is using a proper MEK/Acetone formulation for dissolving some sacrificial Mac case plastics as the properly colored thickening agent. +-

edit: just thought of using various colored ABS filaments for doing MacColor matching. BTW, that particular part may be a lost cause, depending upon whether a thin sheet of ABS can be welded on as a splint.

 
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Yes super glue, and yes, you are right about the surface area, that is why I mentioned the very thin stuff rather than the thick stuff. I haven't been able to get pure ABS cement locally that would be acceptable (rather than the huge, thick glob stuff for pipes you mentioned), so cyanoacrylate has been the best solution I have had thus far. It does still work.

 
A bit thicker/globbier is actually better for repairs and also in fabrication. You can't use acrylic cement on surfaces of parts cut on a bandsaw for instance. Both surfaces need to be "perfectly" smooth for the cement to wick into the joint by capillary action using a needle applicator to properly fuse the parts together. If you melt more acrylic to thicken the cement and brush it onto a less than adequately smooth surface you can get it right with practice.

Methinks that breaks in Mac cases are similar, the jagged surfaces seem to fit back together, but the stresses of the break probably keep the two surfaces jaggedly uneven enough when rejoined that a thick formulation will be needed. Can't wait to see what Paralel comes up with.

 
Okay, so I have this little bottle of stuff that is marked as an acrylic and ABS cement, and I was able to reassemble my totally shipping damaged Color classic and it holds to this day!  I think it is Dichloromethane, but I will confirm when I get home.

 
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