There is a simple, very cost-effective way to lock your strings on the tuners, without any guitar modification. Here's how it works...
Run the string through the tuner's string post. Pull the string almost tight, leaving enough length for about one or two turns around the post. Hold the playing length with one hand and pull the free end tightly around in the opposite winding direction. Then run the end underneath the playing length and, whilst pulling it tightly, bend it around itself in the opposite direction.
How often should I replace them?
String life will vary depending on the string quality, the amount and the type of playing. It is obvious that your strings will wear more quickly if you play a lot, or if you play hard and sweat a lot. With some people they last for weeks, others wear them within one session.
The easiest way to prolonge string life is to play with clean hands and thoroughly wipe the strings clean after each session. Especially with the wound strings, the dirt and oils or sweat from your hands will build up between the windings, thus dulling the sound.
Despite good and thourough cleaning, the loss of brightness is inevitable and in the end the strings will sound dull and lifeless. Change them at least before important performances, in other cases you should judge it with your ears when you feel uncomfortable with the sound. Depending on the money you make on the gig, you also may have take in account if you can afford it.
I changed my strings and my guitar/bass goes out of tune.
You changed your strings, tuned your guitar or bass and it goes out of tune rapidly.
Mostly this is caused by improper setup. Especially with plain strings it is insufficient to run them just once through the stringposts of the tuners and turn them around a few times. They are likely to slide slowly backwards because of the string tension. Winding them around many times is no solution either, because you cannot wind it very tight by hand.
Some people advice to stretch them thouroughly in order to zero out this slack space. However, you should be carefull with stretching the strings. If you pull too strong, you really stretch them, thus deforming the string. Especially with the wound ones you should be carefull. Once you over stretch the core wire, the windings are not tight to each other anymore. They start to rattle against each other, put the string out of tune and finally having it ending up in your waste container.
Avoid too many turns around the tuners. Two or three is enough. Make sure that the strings lock themselves up when you tune them. When tuned up, gently pull and release the string to stretch the slack space out of these few turns. If you like to know a way how to put on your strings properly, read the 'Simple string lock' tip!
Ellio Martina Guitars