Set screws secure one object to another. For example, a faucet stem connects to a faucet handle using a single set screw. While attempting to remove a set screw, you might find that it's stuck due to corrosion or rust. Unlike most fastening screws, set screws are too small for a screw extractor. In removing a stuck set screw, be patient; finding the right solution may require trial and error.
Spray a penetrating lubricant on the set screw, especially in the seam between the set screw and the base of the object. Allow the penetrating fluid to work for one hour, then wipe the set screw head with a clean cloth.
Insert the appropriate size Phillips-head screwdriver or Allen wrench, depending on the screw head, into the screw.
Press down on the screwdriver or Allen wrench and turn the set screw counterclockwise. Often, the penetrating fluid and pressure from pressing down is enough to loosen the set screw.
Hold the screwdriver or Allen wrench on the screw and tap the top of your tool with a hammer. The blunt force sometimes knocks the threads between the screw and the object loose enough that you can turn the screw.
Remove the screw with an appropriate screwdriver or Allen wrench.