"I loathe these things. I've been putting IKEA furniture together for many years and was just working on some pieces yesterday - their HAVSTA bookcases are really quite nice-looking and made of moderately heavy pine boards, so I like them. But I loathe these things. In my experience, about 1/3rd of them turn nicely and rotate 180" into position like they are supposed to. The rest  have lots of problems. Often the hole for the cam is not deep enough, or something isn't quite straight with the screw, or it doesn't extend quite far enough into the hole for the cam. The result is that I can't turn the thing all the way around. I am only using hand tools since I have learned the hard way not to use powered screw drivers to turn these things. I've torn the prongs right off even trying to tighten them with a screwdriver. It seems like the cams are made of a poor grade of metal. Even with a properly-fitting screwdriver, sometimes the screwdriver socket will break, leaving bits of broken metal..Fortunately they seem to hold well enough even if they don't quite work right, but they are unpleasant to work with and I would dearly love to see an alternative method in future versions of these furniture pieces."