I've grinded stems before and all it did was give me stem powder. I didn;t have a kif catcher. I just tossed them all in a grinder, grinded them, and smoked it. :p Ha ha! I know, duh!
I did see a video on
www.waytoomany.com called "don't throw away your stems." All they did was they made a shaker, and put a silk screen screen, on the end of it so you get nothing but the trichs. I made one very similar to theres and I've tried it twice now. Works like a charm and I get some nice potent kif from doing it.
Hey, it's better than tossing them or smoking them as a whole.