For years was taught and have been using pc-7, but kardol sure would be alot easier and cheaper.

So, assuming I properly sanded and preped surfaces, has anyone had any failure with kardol or rod bond ,when used on ub2 and ub4 ferrules?

PC7 is a poor choice on any close fitting assembly. It's a paste and intended to be used for gap filling purposes. A well fitted uni-butt ferrule to rod butt joint should be joined with something less thick, such as Rod Bond, Kardol, or any good liquid 2-part epoxy. Strive for a close fit and thin glue line. If your pieces fit snugly, Kardol gel type epoxy should be fine.

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Been using Kardol for Years

I figured it would do. Man, for years I would have to sand the butts down good enough to get pc7 inbetween the surfaces and when the stuff got too stiff over time we would trash it. What a waste.

I used Rod Bond for years and never had a failure. For ferules that were a tight fit that would want to push back off of the blank after putting it on, I drill a tiny hole in the bottom of the ferrule, normally in the groove, to allow air to escape and not compressed inside the blank. Now, we use PC7 and do the same drilling process to avoid having a ferrule that slips back during the curing process of the PC7.

I usually put the tip on last to let air escape through the hole at the tip of the blank. I've been experimenting with liquid plastic and making the piece that makes up the difference between ferrule and the blank from a clay mold and fastening everything with low viscosity 2-part.