Sometimes even a simple tast, like installing a new set of tuners, may require tools that you won’t find in your garage. So, before starting a job, think it through to make sure you won’t be stuck without a critical tool midway through. I used several uncommon tools to install new tuners (Stewart-MacDonald Adjustable Tension Bass Tuners and a Hipshot Xtender Key) on this P-style imported bass. Fig.1 After removing the old tuners, I went about removing the grommets that were pressed into the peghead face, because the new grommets were considerably larger than the stock ones. These grommets, or bushings, support the tuner shaft under string tension. Sometimes simply wobbling a round steel bar (a screwdriver shaft works well) inside these grommets in a circular motion is all it takes to loosen them enough to lift them free. Unfortunately, these grommets didn’t cooperate. Fig.2 I slowly pressed the grommets up and out with a hefty machine bolt, inserted and clamped from the underside. To support the wood and keep it from fracturing as I pressed the grommets out, I dropped two large, flat washers right over each grommet’s outer diameter. Fig.3 The holes for the original tuner grommets measured g" (.562"), which is far smaller than the 23/32" (.718") holes needed for the replacement grommets. In many cases a tapered hand reamer will work for enlarging tuner holes, but even my large peg-hole reamer wasn’t big enough for bass tuner grommets. A file and elbow grease is one sure way to enlarge the holes, but it’s difficult to ensure accuracy. If the holes are off center, the tuner bass plates may bump into or overlap each other when you install them. I decided that the neatest and most accurate method would be to drill the holes larger. I used an electric hand drill rather than my drill press so that I would be at the same disadvantage as anyone reading this column who didn’t have a fully equipped woodshop. Drilling a hole in an existing hole is tricky because the drill bit has nothing to center on; without wood to drill into, the bit can jump dangerously out of control and mar the peghead face. My solution: I whittled, filed, and sanded a y" birch dowel from the hardware store until it would tightly fit the holes. I then sawed the dowel into four pieces and pressed them into the holes. Now I had wood to center my Forstner drill bit on. Unlike the V-shape of common twist drill bits, Forstner bits have a spur center, two sharp cutting blades, and a ring of teeth on the outer edge that produces very clean holes. Forstner bits stay centered on holes better than other drill bits. With the peghead face-up and clamped flat on a hardwood board (as a backup for the drill bit when it exited), I was able to drill the new holes. I used a e" drill bit, which was slightly larger than the grommet’s exact diameter. I would take care of this size mismatch later. Even with all of these precautions, I got a little off center on the A-string hole—not by much, but possibly enough to cause trouble down the road. Fig.4 This would not have happened had I taken the time to make a “drill jig” by drilling a hole in a scrap of hardwood or acrylic. Such a jig can be carefully centered on the hole to be drilled and then clamped to the backer board along with the peghead. The jig will keep the bit perfectly centered. Fig.5 When I installed the A tuner, it bumped into the Xtender Key, so I had to file a bit off the end of the A tuner’s base plate. I could blame it on the spacing and drilling of the original holes, but I filed off just about the same amount that my hole was off center! Notice in the photo that the mounting screws for the Hipshot are flat-head screws rather than the round-head screws normally used to mount tuners. This is so that the Xtender Key can rotate over the screw heads when in use. Fig.6 The Xtender Key also needs to clear the holes in front of it (on the A tuner) when it rotates. The thickness of the new tuners’ flat base plate is .075"—that’s .015" thicker than the base plate of either standard Fender bass machines or Schaller bass machines. The extra thickness meant that I had to file .015" off the top of the two mounting screws adjacent to the Xtender Key. I screwed two mounting screws into a scrap of wood to hold them while I filed off the unwanted metal. When I was done, there was still plenty of depth in the screw heads to use a phillips-head screwdriver. I could have avoided this procedure by installing the Schaller tuners, because their plates are only .060" thick—but my customer wanted the option of being able to adjust his tuners’ tension. (An allen-head screw on the end of the shaft can be tightened or loosened so that the tuning key turns stiffer or easier.) Schaller Bass tuners are not tension-adjustable. Fig.7 I wrapped masking tape around the drill bit (a") that I used for the mounting screws; this tape served as a depth guide to keep me from drilling through the peghead face. Placing a magnet on the screwdriver shaft, so that the screw sticks to the tip, makes it easy to locate and drive in the screw. Fig.8 I got the grommets to stay in the slightly oversize hole by smearing beeswax on their fluted edges to take up the slop (the arrow points to the wax). A small amount of Titebond wood glue, brushed around the flutes, held the grommets in place once it dried. Fig.9 Now, all that was left was to reassemble the Hipshot Xtender. (Before installation, I had removed the machine screw, gear, nylon spacer washer, string post, and wave washer.) If you try this modification, be sure to put the wave washer on the post before you install it up through the peghead hole from the face side. It does not go on the plate side. I mention this because when I disassembled the tuner, the parts fell onto the floor before I could observe the order in which they were assembled. The Hipshot instructions show neither the wave washer nor where it belongs; it would be easy to think that it installs from the backside, but it won’t work that way. Fig.10 I followed the Hipshot instructions to reassemble the rest of the Xtender Key: string post and wave washer up through the hole, nylon spacer slid over post, crown gear placed over post end and spacer, and machine screw tightened, bringing it all together. Fig.11 Then came the fun part—seeing the smile on the customer’s face!
	—Dan Erlewine works on new product design and is the staff writer for Stewart-Mac-Donald’s Guitar Shop Supply in Athens, Ohio. Dan still builds and repairs basses and guitars in his home shop. His monthly repair column Repairs & Modifications, and numerous feature articles, appeared in Guitar Player for 16 years. His books, Guitar Player Repair Guide (1990) and How to Make Your Electric Guitar Play Great (2001), are published by Backbeat Books.
	Orginally published in BASS PLAYER magazine. Copyright © 2006 CMP Entertainment Media. All rights reserved. Used by permission.