For some reason, two of the rotors on my Academy 1/35 MH-60G broke off, but is was clean, and the little bits that went inside the hub are stuck there. I tried Testors plastic cement, Elmer’s superglue and Gorilla Glue, but they always sag once the glue is dry! Is there a type of glue that is completely solid and won’t make my rotors sag?
I think that for a repair like that especially, you need to use a liquid weld. This will literally weld the two pieces of plastic together making a stronger bond than any superglue or epoxy.
There are various brands. I use Weld-On 3. Ambroid Pro-Weld or Tenax are other options as are various liquid glues from Tamiya, Testors, etc. Some folks just use straight MEK.
Whatever you use, make sure you have a clean and smooth mechanical connection before gluing. The parts should fit together cleanly with no gaps and there should be no paint or old glue left to contaminate (and weaken) the weld. Sand smooth and repaint after the parts have been securely connected and left to dry a few days (to a week).
You may also need to investigate if it is possible to very carefully drill out and pin the parts with metal from a sewing pin, safety pin, needle, etc to provide more strength to the joint.
I’ve had to repair three of mine so far, the fourth is due to drop any day now! I would say, forget about trying to just glue them back on. I drilled out both, the hub and blade and used pieces of brass rod, roughly 3/16ths" long. (avaliable at your LHS or hardware store for about $1). I superglued the rod into the blade, and it just slides into the hub, with no glue needed, that way, the rotor can be disassembled for transprot.