Tuner Peghole Reamer
Have you ever had someone take their guitar to you and ask you to replace their tuners? But once you take the old tuners off and line up the new tuners, you realize that the new tuners are too big for the old pegholes. What do you do? Do you grab a drill and try to drill the holes out larger? The answer is, no. In the process of drilling out the old holes you could crack the lacquer or worse chip the headstock. The only good way to enlarge the tuner pegholes is to use a guitar tuner peghole reamer.
A guitar tuner peghole reamer is an elongated reamer that is tapered. These reamers are generally fitted with a handle, so you can hand ream all the holes. Hand reaming the holes reduces the risk of carelessly cracking the lacquer or chipping the headstock. Don't just buy any tapered reamer. A proper peghole reamer has a taper of 2 degrees. You will want a nice sharp peghole reamer. Remember, you are cutting through not only the wood but also the lacquer. Your peghole reamer must be sharp and fluted properly, so you don't damage your guitar in the process of enlarging the holes.
A peghole reamer is a great tool to keep in your guitar repair shop. Without one, you could crack or chip your or a customers guitar. Just the cost of fixing one crack would pay for the peghole reamer. If you do any tuner work at all, I suggest you get one. They typically come in three different sizes with approximate cutting lengths of 4.5, 6.5, and 8 inches. Most commonly the two smaller sizes are used for violins and small guitars. A typical guitar peghole reamer has an approximate cutting length of 8 inches and a taper from .3" to .625". With a good quality peghole reamer, you will be able to enlarge any peghole to accommodate the new style of tuners. If you would like more information about how to replace guitar tuners, please see my how to replace guitar tuners article.