Guitar build CD60-3 – Dell Sweet – Bridge work


Bridge Blanks ready to go

In this chapter I will work on the bridge area of this build. I have a bridge left over from a previous Ovation build and I want to use it on this guitar. I could have made things simpler by ordering a replacement Fender bridge to replace the cracked one that was on this guitar, or making one, or using a  replacement. There were a lot of possibilities, but I wanted this to be something that would make string changes easier and faster for me.

There is pro and con about mounting strings topside as opposed to mounting them into the body with pegs. Some feel that there is less string energy transfer with the top mounting, and that the two screws used to reinforce the mounting point of the pinless Ovation style bridge bring in more treble than normal.

My own observance is that there is plenty of string energy transfer, but I have observed a slightly higher resonance on the treble side; by ear, not measuring with any sort of instrument. That works for me because I do a great deal of finger picking as I play and I like to be able to clearly hear each string. If you have a set up that is heavy on the bass side of things you lose some of that individual brightness from the higher notes, lower strings.

I have found with other builds that I have done that brass screws used to anchor the bridge, as opposed to steel, will mellow that sharpness and introduce a little more bass.

I will start with prep work. The space that the old bridge occupied is rough, still contains traces of glue and needs to be leveled to make sure that the new bridge installation is correct. I will show this even though my own direction for this guitar will negate this step, as I will be repainting this body in a solid color, not stain, and so I will be sanding the bridge area down. But I want to show what you should do if you planned to save the stain and finish currently on this body.

Most likely the failure of this bridge was due to the incorrect prepping of the area under the bridge. You can see areas of gloss that were not removed, and the underside of the bridge contains that gloss, ripped right from the surface of the soundboard after it received a shock of some sort: Being dropped, hit, something that caused the bridge to detach.

What I didn’t find was any kind of trauma to the soundboard or that area of the bridge. No stress fractures in the finish, no cracks in the surface, no deep gouges in the wood from tear out. Nothing like that. That suggested to me that the bond was not adequate. And most likely a moderate shock just caused the bridge to come lose.

Prepping the area means that you should get down to the wood surface. Yes you can use epoxy and bond directly to the finish surface, but that is not going to be the best bond, it can easily pull apart like this did by pulling the finish from the surface. And you can’t use wood glue on the surface for the bond and expect that to work. Aliphatic resin can give a good bond if it is wood to wood. That isn’t so hard to achieve.

If I am building a guitar from scratch, or re-installing a bridge I will make sure that I am down to the wood in that area. I will also make sure before I get to the finish work that I have checked the scale, test mounted the bridge. If it is custom work like this build is, I will draw a rough plan to keep me on-track. How did I envision this, how did I envision that? Committed to paper where I can easily refer to it, it is easier not to make a mistake. You can see the screw holes for the mount. I will use brass screws, as they will give me plenty of strength and a nice mid range punch.

With this Fender CD60 build I made sure that I drew the changes out and they will go in a file so if I am ever working on this guitar again I will know exactly what I changed. That makes sense if you do a lot of builds or a lot of different repairs. It can instantly refresh your memory when you look at the drawing. At least that works for me.

What follows are the approaches I could take to repair this top. As I said I will be painting this top and so I will sand it down and prime it. But you may wish to re-install a bridge on whatever you are working on, and repair just the small area of finish around the bridge,  and blend it. So I will illustrate three ways to repair this bridge.

I have used a sharp chisel to remove the finish from the area where the bridge will glue down. I used very little pressure, just enough to remove the finish, not wood.

The sole reason I will be sanding this top down is because of my desire to put an alternate finish on the guitar.

The first step would be to carefully mark the new bridge position as I did, use the flat, sharp edge of your chisel to remove the finish from that outline you have made. What we are looking at is getting to the wood surface so that we will have a solid wood to wood mounting point for the bridge. I have a few dozen chisels, rasps, files, and similar hand tools. Whenever I see a file or rasp, chisel that I don’t have I buy it. I may only use it occasionally, but it will be worth it to me. I always keep my chisels sharp too. It doesn’t take much to do that: A wet stone, a grinder if you chip the chisel so that you can bring it back to square again, and that is about it. A sharp chisel doesn’t need to be pushed or shoved so that it gouges the wood out. A sharp chisel will cut whatever is in front of it smoothly with very little pressure. I also tend to use my chisels upside down: Grinding a small bevel on the opposite side when I sharpen them. It allows me two angles, high and low, I can use to rock the tip and cut with the chisel. All I am doing with this chisel is removing the finish. I am not leveling the raw wood underneath that finish, or trying to take out any of that wood. You can see where the sealer is still on this wood. The clear coat separated from the sealer. My guess is that the painter waited too long to shoot the clear coat over the sealer, and didn’t sand the surface at all, simply sprayed it.. So there was nothing for the clear coat to stick too. It needs to be scuffed for adhesion of the clear coat to the sealer coat.

What you can see above is the outline for the Ovation bridge and the finish that needs to be removed. You can also see ridged up clear coat that was sprayed around the bridge on a previous repair, probably the initial attempt to repair this bridge, and you can see where the surface that was glued or epoxied pulled free of the wood. The clear coat finish is not porous enough to allow the glue to get a good grip. Wood has enough porosity to allow the glue to get the maximum grip by allowing it to penetrate deeply into it.

The next thing to do is level the top near the bridge area. I will use the same tool I always use to accomplish leveling, a razor blade held at an angle. It makes the job easy and fast. It doesn’t mess up the area around what I am leveling and if done correctly it isn’t going to cause any gouges or problems with the finish. The idea is to save time, but also to get exactly what I need, in this case, leveling, if I were going to save this finish. There are tools, levelers, made for this exact purpose, and also for smoothing the raw wood top on a guitar build, but the razor blade works perfectly for this size repair area.

I am pulling the razor blade to me across the top, skimming the finish flat.

I am only trying to remove the ridge of built up clear coat at the edges of the old bridge mounting so that if the old bridge were remounted and the top blended it would not show.

 A few passes with my blade and the process is over. The top in the bridge area is as flat as it will be.

At this point if I were reattaching the bridge and saving the top finish, or reattaching the old bridge, I would be finished with the top prep entirely, and I would be ready to glue the bridge down, or mask the area and spray the clear to blend it in.

First Scenario, reattaching the old bridge: This is the easiest fix. All I would do is remount the bridge exactly as it came off. The wood would be there now for a good bond. The outline would be flattened so there would be no ridged clear coat near the bridge. Since there was no other damage to the top there would be nothing else to do.

I would take a small amount of rubbing compound and smooth the edges of the outline since they were dulled out by the scraping to level them.

That would also polish it up. I would then use a little lacquer thinner to clean the area before I remount the bridge.

Mounting the bridge is not hard to accomplish. You don’t need special clamps, although there are clamps made to accomplish the task. With an acoustic bridge that uses pegs, or with a pin less bridge that uses screws to attach it, there are holes through the bridge into the body. It is a simple matter of using screws through those holes to serve as a clamp for the bridge.

The scrap wood is a piece of 1/4” thick pine 1 1/2” wide, 6” long. I have cut plenty of these right from the edge of a scrap of 2” x 4” lumber. The two blocks at the end are two pieces of 1 1/2” by 1 1/2” by 1/8” Luan glued to the 1/4” pine at either end. I can use soft cloth on the base of those Luan pieces, or I can use small glue on protective pads to do the same thing, protect the bridge surface from marking. This tool sits right on top of the bridge, nearly flush in the middle, pressing the bridge on the ends. The holes through are drilled to line up with the peg holes on the ends of the bridge, 1 and 6 with an 1/8” drill bit. I use a set of bolts with wing nuts you can pick up at any hardware store. I slip the bolts through from the bottom, and then through the bridge, tool, and then into the wing nuts.

Test fit the tool you have just made from scraps. Once you are sure everything is lined up properly, remove it. Using Aliphatic Resin carpenters glue coat the two surfaces. Rub the two surfaces together lightly and then line the bridge up with the holes for the pegs and slip the bolts through from underneath, settle the pine piece on top and tighten the wing nuts slowly, until the glue begins to squeeze out from the joint. Don’t go past that. You are holding the piece in place, that is all. You will notice a few things. First, the center of your piece of pine has now bowed down closer to the bridge top, and second, the glue is squeezing out all around the bridge fairly evenly.

Use a damp cloth to remove the excess glue and then let the guitar set for 24 hours. The tool you made can be used over and over again.

Second scenario, attaching the new Ovation bridge:

This is slightly more work but not much. We will follow the same steps above to prepare the area. The difference here is that this replacement bridge from the Ovation does not cover the same area as the Fender bridge did. It leaves very small corner areas exposed that are not clear coated. There are two ways to take care of this problem. The first is to mask the new bridge area and over spray the top with clear just at the bridge area.

That will do the job, but it will mean a little sanding to bring the surface down low and then some buffing to bring it all level and shine it up.

Two very small repair areas remain.

Here the bridge is test fitted to see how much repair area there is. I have already outlined this area to remove the finish with the chisel and then to flatten it with the razor blade, and I have drilled two holes that line up with the ones in the bridge that were originally used to attach it to the top of the Ovation.

Once I know exactly what is needed for a clear coat repair I can do it. If I were keeping this top I would also have to account for the sun damage and blend some color into the bare wood as well. I would use some color mixed with thinner, and then hand rub it to get the color I want. With this, or any sun damage, it’s going to be a small amount of yellow mixed with light brown. I’ll look at it and blend and thin until I get a good match. If it is darker I will rub it down with thinner and that will lighten it. Too light and I will darken it back up. I’m talking very small amounts of paint mixed with thinner here, something I would mix in a bottle cap, or something like that, and apply with a tooth pick until I get what I want for a color match.

Once I have the color matched I will use a toothpick or a small brush, depending on the size of the area, to apply clear directly over it and cover the area that is missing finish. The toothpick is nice, because you can watch the drop of clear on the end of the tooth pick flow into the area. It blends into the old clear, and it covers the bare area. Let the finish come slightly over the existing finish. The clear will naturally want to do that, form a solid surface that will arch above the existing finish. As the clear dries it will shrink slightly as the thinner dissipates. Let it sit for 24 hours, sand it lightly with 400 grit paper on the edge of your index finger and then use rubbing compound to blend the repair and bring it back to a shine.

The same technique can be used to repair finish chips on a guitar as well. The clear can fill in a small chipped area, or finish that has been lost, and easily be scuffed lightly and rubbed out. In some cases, on smaller chips, there is no need for sanding. A light rub and the repair area is nearly invisible.

For practice, take an old finish on something that has been dulled out and use a little rubbing compound to bring it back to life. This will familiarize you with how easy it is to level paint, clear coat, and bring not only the repair area to completion but also return a uniform shine to the surface.

Another trick for small chips or tiny areas missing clear coat, is clear nail polish. Most nail polish is Lacquer and it will accomplish exactly the same thing that the clear will. It also comes with a handy applicator brush in the bottle. Fill the chip. Let it set, rub it out, done.

Third Scenario: Attach the Ovation bridge to a readied surface.

So we have test mounted the bridge, next I will sand the body to flatten the bridge area, and the area under the pick guard. The adhesive came off but also revealed some deep finish scratches under the clear coat: Probably neglected because they would not be seen. There were a few other top imperfections that I wanted out, but only to the point of being flat, not taking out imperfections in the clear such as dust, and other debris.

As mentioned, although I outlined how to repair the area, I am going to repaint this top with a solid color, so I will go ahead and take out the imperfections I find, not caring whether I burn through the clear coats as they will not be seen after I am finished.

You can also see the grain, what you might not be able to tell is that the grain is raised through the finish (Left, in front of the bridge space). The finish looks like the sealer was sprayed and never flattened, just the top clear coat was rubbed out to a shine. The problem with that is that as the sealer under the clear dried it sucked down into the grain of the porous wood. Then the clear was sprayed over that and also sucked down into the valleys in between the grain left by the sealer that were not sanded out. The whole idea is to spray that sealer or primer if you are covering with solids, sand it flat, then shoot your color coats or clear over that flat surface. Let it sit, scuff it if there are any problem areas and then rub it out. When you skip the sanding step and only rub it out, the rubbing compound will take even coats off, leaving the dips and valleys of the grain.

Here I have sanded the top flat. I am not concerned with removing the entire surface as this is a solid color repaint. You have to remember to be very careful here as the top is only 1/8” thick. Go slow. Level the problem areas and don’t go past that. If you still have small problem scratches or nicks, use lacquer filler and then sand it lightly before you prime or seal the surface. You can see the extra holes have been drilled in the bridge area for the Ovation style bridge when I test fitted it.

I took two of my small precision screwdrivers, lined up the holes, measured my scale and then drilled the holes.

The only other thing that remained was to take the finish off the bottom of the bridge area, and put a small curvature in it to match the Fender body.

The Ovation top is very flat, the fender is not. Although guitars like this are often referred to as flat tops, they are not flat at all. The maker builds a curvature into the top and the back. That curvature builds strength and tension into the top. I used the bench sander to build that curvature into the ovation bridge back. I went slowly test fitted several times and then finally reached a place where I was happy with it.

In the next chapter I will scuff the rest of the body so it will take a sealer/primer coats.

The above material comes from the CD60 Repair manual – Guitar Works Four:

Guitar Works Volume Four: The CD60 Build Geo Dell. This volume contains the complete Fender CD60 build. This is a complete start to finish custom build. The base is an Fender CD60 Acoustic cutaway guitar. #GuitarWorks #fender