Guitar strap buttons and end pins are often confused with one another. Although end pins can be used to attach a guitar strap, their purpose is to provide a resting point to keep the guitar end from contacting the floor when placed upright. End pins differ from strap buttons in that they are attached to the guitar through a hole bored through the body, and must be installed by a qualified guitar technician to avoid damage to the guitar. Strap buttons attach to the guitar with a wood screw, involving a less invasive procedure.
Find the centre point of the back side of the guitar by measuring with a ruler, and mark the spot by making a small hole with an awl.
Compare the strap button screw with various drill bits until you find a bit that has a diameter slightly smaller than that of the screw.
Insert the screw into the strap button fully, and place the drill bit (pointed side toward the button lip) parallel with the pointed side of the screw, until the bit contacts the bottom lip of the strap button. Wrap a small piece of masking tape around the drill bit where the pointed screw ends. This serves as a depth guide for the bit when drilling.
Insert the bit into the electric drill and tighten it securely with the drill chuck.
Place the drill bit against the awl mark and drill slowly until the bit is inserted into the wood to the depth of the masking tape mark.
Choose the next largest drill bit and drill a very shallow countersink hole over the original hole. Only drill the countersink hole until the surface of the original hole begins to visibly widen. This step is optional, but may help prevent the finish around the hole from cracking as the screw is inserted.
Insert the screw into the end pin and rub a small amount of candle wax or soap on the screw threads for lubrication.
Insert the screw in the hole and tighten it with a screwdriver until the strap button contacts the guitar. Tighten only enough so the strap button cannot be turned on the screw, as over-tightening may strip the screw hole.
If the screw hole becomes stripped, or a larger bit was accidentally used, dip a toothpick (or two) in wood glue and insert it in the hole. Break off the excess flush with the guitar surface, and reinstall the screw and strap button. Some end pins are supplied with a small, circular felt or leather washer which is placed over the screw, forming a pad between the strap button lip and the guitar surface. You may make your own by cutting a piece of felt or leather to the size of the button lip, and placing it over the screw before installation. Periodically check the tightness of the strap button by attempting to turn it with your fingers. If the button turns, tighten the screw. Installation of strap buttons on electric guitars is done by following the same steps.
It is not recommended that you install a strap button on the guitar neck. Installation in the wrong place can affect the structural integrity of the neck, and should be entrusted to an experienced repair person. Guitar straps are attached to acoustic guitars with no neck area strap button by tying them around the headstock, just above the string nut under the strings. If you wish to have a button installed on the neck, a repair person can do the job safely, quickly and inexpensively. Guitars have internal braces that provide support and strength to the guitar body, which is why end pins should always be installed by a professional. Disturbing or weakening the braces can cause serious structural damage to the guitar.