Brian's Guitar from Conception to Birth or How to Build a Guitar in 62 Easy Steps!
34 Oops!
Shit happens! With woodworking, as with playing in a band, it’s not how bad you fuck up, but how well you cover up your mistake. The idea is to take your mistake and use the opportunity to make something from it. Most guitar instruction books show you that everything works great the first time, but that is rarely the case. So here is how I dealt with one of my unfortunate moments. When drilling a couple of the holes for the through-body string ferrules, the thin bit deflected and did not come out on the backside of the guitar exactly where it should have. The holes weren’t lined up and it looked bad enough where I wasn’t happy with my work. So you sometimes have to say, “Gee, that would be a nice spot for an inlay.”
First, plug the hole. We chose to cut out the entire area of the string ferrules on the back body panel. Use double-sided tape to secure a couple of stop blocks at the limit you want to cut out. Drill a larger pilot hole in the middle of the area which will allow your bearing guided router bit to get through. Flip the body panel over and rout out the offending area. Using the same species of wood, cut a patch and fit it into the hole you just routed. Take your time with some 60 grit sandpaper to achieve a tight fit. Glue the patch in place and sand both sides flush with the adjacent surfaces. You could stop here, but the patch is still noticeable and not what someone would expect from a custom made guitar. An inlay will hide the seam with some complementary colored wood (or you could use pearl).
Make a template for your inlay. We’ll use the same concept as when we made the control cavity cover. We’ll make one template which is a 1/4" wider all the way around which can be used to cut both the cavity and the inlay. To cut the cavity, secure your template to the back of the body panel with double-sided tape. Double-check your measurements so you don’t fuck up the fuck up you’re trying to fix. Chuck up an 1/8" diameter router bit with a 5/8" OD guide bushing and set the plunge depth. Clean out the whole cavity. To make the inlay, secure the same template to your inlay material with double-sided tape. Secure the inlay material with the template to a piece of scrap would with double-sided tape. Make sure you get a piece of tape directly under the piece you’ll be cutting out so it doesn’t go flying across the room when it’s set free. Using the same 1/8" diameter router bit, install a 3/8" OD guide bushing. Set the plunge depth to just below the thickness of the inlay material. Position the guide bushing against the side of your template, plunge through the material, and rout your way around the perimeter. Test fit the piece into the cavity, but don’t push your test fit too hard or you won’t be able to pull it back out again to glue it. You will have to do some fine tuning with some 60 grit sandpaper to get a tight fit. Since my inlay is symmetrical, the blue tape shown on top of the inlay (right photo above) reminds me which side is up.
Now glue it up and make it pretty. Apply a thin layer of glue to your inlay and press it into place. Use a clamp with clamping block to evenly distribute the pressure. Let it dry for at least an hour, preferably two. Clean up any glue squeeze out with a small chisel or screwdriver. the inlay may not fit perfectly, so tape off the seam and apply some appropriately colored wood filler with a small screwdriver. Wood filler does exactly what it’s name describes, fills wood. Though the manufacturer will tell you the filler is stainable, it will not take stain the same as the surrounding wood. The tape protects the surrounding wood from getting clogged with stray filler. It might not be obvious now, but it will be when you stain your guitar. Then it’s too late to fix it. Take the time to tape things off.
Lastly, fix the original mistake. Make a template of your string hole pattern from some 1/4" MDF. Mark and drill the holes in the template using a drill press. Carefully locate and secure the template on the back body panel. Now take your back body panel to the drill press, set the depth if you need to (our holes were drilled all the way through the back body panel), align the drill bit with your template, and drill the holes. The template helps keep the drill bit from deflecting. In hindsight, we probably should have used this approach the first time through. Double-check that the holes are continuous through the guitar and clean up any transitions between the new holes and the old holes with a file. The result should be perfection, and your client will get a nicely coordinated bonus inlay. Your mistake might be in a different area, but the concept will probably be the same: find a way to make something special from your mistake.