Guitar Nut Saws
Guitar nuts are made out of very dense materials. Some guitar nuts are made out of wood, plastic, and tusq, but the most common material is bone. Guitar nuts are made out of dense materials because dense material is structurally sound and transfers the vibrations from the strings to the neck efficiently. Given the small size and denseness of most guitar nuts, it is difficult to cut a guitar nut down to size with standard tools. That is why gauged guitar nut saws were invented.
A gauged nut saw is simply a small hand saw that has very thin, sturdy blades. There are several different common sized gauges for nut saws starting at .010" to .030" thick. These saws are extremely accurate and can be used for many repairs. As I mentioned above, these gauged saws can be used to cut nut blanks down to length. They can also be used to cut kerfing down to length. For those who don't know what kerfing is, it is the wood strip glued on the inside edges of acoustic guitars. I think the most useful repair I use this tool for is to lay out my guitar nut string spacing. After I pencil in my string spacing on the nut, I take a gauged nut saw and start cutting the string slots on the top of the nut. Nut slotting files can be used for this, but they tend to creep one way or the other until the slot gets started. By that time it might be too late because the slot might be in the wrong spot. Starting the string slots with a nut saw ensures that they are started properly. After the nut slot is started, a nut slotting file can easily pick up the slot and file it to its final depth.
A gauged nut saw is a must have guitar repair tool for everyone. It has so many uses that you will find out once you buy one. I think laying out the nut string spacing is one of the most important purposes. This tool really helps with accuracy of string spacing while speeding the repair along. I don't think that you need to get a set of them, however. Eventually, throughout your career you may want to pickup a whole set of different sizes. I'd recommend getting the .010" saw first. After you use that for a while, you can judge whether you need to buy the rest. If you would like more information about replacing guitar nuts, please see my how to replace a guitar nut article.