Replacing the bindings on your skis with a different pair is not all that uncommon, but it usually requires more effort than just unscrewing the screws. If the bindings were mounted properly, glue was used to seal out water and prevent the screw from vibrating loose. With good glue, it will not only prevent vibrating loose, it will also do a darn good job of preventing you from even loosening it at all without striping the head.
There are two ways to overcome this.One is to use an impact wrench with a posi-drive bit. In my experience this works, but only rarely because few people own an impact wrench. You can try to twist while smacking a regular posi-drive screwdriver with a hammer, but this usually only damages the screwdriver handle, and sometimes the handler.
The more reliable way is to heat the head of the screw with a soldering iron. Usually you need to hold the tip on the head of the screw for at least 30 seconds; that depends on how hot the iron is, and how well it conducts heat to the screw. You will still need to apply a fair amount of pressure when trying to twist ‘er loose, but once you break the bond the screw will come out easily. If 30 seconds doesn’t do it, quickly heat the screw another 30 and that should do it. If it doesn’t, find an impact wrench.
Got another trick you use? Please share below.