Nut Slot Chisels
In my nut seating file article, I talked about how a nut seating file is used to clean a nut slot that has hardened glue in it. What happens if there is a large amount of hardened glue in the slot? Should you just sit there with the file and file it until all of the glue is removed. The answer is no. This could take a while to get all the glue out of the nut slot. You may also damage the nut slot by filing unevenly while trying to wear through the glue. A nut slot chisel is the best tool for removing this type of hardened glue.
A nut slot chisel is also known as a micro chisel. It is a miniature chisel that is attached to a handle about the size of a pencil. The chisel end is usually bent in about a 135-degree angle. This angle allows you to put pressure on the end of the chisel while you are running it across the wood. Nut slot chisels or micro chisels are also useful for removing hardened glue from inside acoustic guitar saddle slots and acoustic guitar braces. All in all, the nut slot chisel works the same way a normal sized chisel works. Simply place the blade of the chisel flat against the wood with the bevel facing up. Now run the chisel diagonally across the wood at a slight angle. The wood should peel right off. There are tons of ways to use a chisel like this, but this is the most common.
A nut slot chisel is an extremely useful tool. I would recommend that all luthiers get one. It is not an essential tool, however. You can do nut repair work and saddle repair work without having a micro chisel. That is why I'd say if you are just starting out, you don't really need to buy one. After you start building your stockpile of guitar repair tools, you can put this one on the list. It is an important and useful tool, but there are more important tools out there. If you would like more information about replacing guitar nuts, please see my how to replace a guitar nut article.