Natedogg --
sprchng's advice in his post is, in my view, ALMOST spot on. Abrading the surfaces with sandpaper, cleaning with isopropyl alcohol to remove dust/grease, etc. And yes, hitting it with a low flame from a propane torch is also valuable -- especially for many of the "harder to bond" plastics, such as Delrin, etc. These types of plastics, molecularly, make bonding difficult, and the flame "oxidizes," or "alters the surface molecular structure" of the plastic, allowing a better bond to be achieved.
Clamping, I'm not so sure. Most epoxies have a specified range of "gap width" that is most appropriate (i.e. space between the two parts to be bonded). Too large, OR too small, on that "gap width," and you won't achieve maximum bond strength. And while, along these lines, sprchng noted not to clamp it TOO tight so as not to "squeeze out the epoxy," I still think that the "gap" that would exist -- when clamping -- would be smaller than what most epoxies are spec'd at; that "gap" data is available from the manufacturer.
The one thing I will disagree with, is the idea that "the type of epoxy is not so important." I would counter-argue that the type of epoxy CAN -- depending upon the materials to be bonded -- be CRITICALLY important. Epoxy manufacturers offer DOZENS of different types of epoxies/adhesives, and there's alot of "chemistry" and such behind that...as certain adhesives are required for certain materials, and others, for other materials. Plastics are NOTORIOUSLY difficult to bond, and then plastic-to-plastic is VERY difficult, in terms of achieving a very high-strength bond.
The one I would try -- but it requires an epoxy gun -- is Scotch-Weld DP125, in "gray" (it comes in both a translucent amber color, and a gray color). It's a two-part epoxy, requiring the appropriate gun for the size of epoxy cartridge you buy; I buy the ones that are like 48.5ml, as those are the ones that fit my gun. You'll also need mixing nozzles (the 1:1 green nozzles) if you choose to go this route.
Otherwise, for plastic-to-plastic bonding, it's tough, with off-the-shelf epoxies. You could try the JB Weld "PlasticWeld" syringe, but I've not tested it, so can't recommend. But, it is at least SUPPOSED to be "optimized" for bonding "plastic." If that doesn't work, you might try the ORIGINAL JB Weld steel-reinforced 4-6 hour formula (not the KwikWeld 6-minute version).
Hopefully this helps a bit.
Steve
