Repair Services

This guitar is a Gibson L-0 from 1926 to 1928. It came to me with one back brace out of the guitar and all the rest loose, several top cracks, a cross-grain fracture in one side, some looseness of the back to rim glue joint, a badly split bridge, and in need of a neck re-set.

Click on the thumbnails to see larger images.

Here’s how it looked starting out.

Here’s the side fracture. It is right where the end of the missing brace was. The brace is still with the guitar, not lost, but missing from it’s place on the back.

The worst top cracks, structurally, are these, beside the fingerboard.

The bridge is a pyramid  type, and is badly split through the pin holes.

There is too much work needed inside this guitar to consider  doing it reaching through the sound hole, so my first order of business is to remove the back from the guitar. I wanted to save and re-use the back binding, so I carefully separated it from the wood with a thin palette knife blade. It came off very cleanly, in one piece, with only a couple of small splinters of wood that were easily glued back into place.

I removed the binding in one piece because, unlike on later Gibsons, the binding does not have a butt joint, but instead has a scarf joint. With the usual butt joint, the binding can be separated at the joint, removed, and put back on after repairs as a long strip, more like new binding. I didn’t want to separate the securely glued scarf joint on this one, so I managed to remove the binding in one piece.

With the binding removed, you can see that there is some failure of the kerfed lining inside the guitar where the side fracture is.

I used a thin blade to separate the back from the lining. I sacrificed some of the lining in some of the “stubborn” places rather than take a chance of damaging the back. Here’s the guitar with the back removed. You can see the unusual bracing pattern and some pieces of the damaged lining.

Here’s the back with the missing brace lying near it’s proper position. All of the braces are loose and will have to be re-glued.

All the braces popped off without any damage because the original glue joints were so poor.

The gluing technique of whoever put this guitar together left something to be desired. There were many places where the glue did not transfer from the brace to the back, so they were only glued in some places, and not all the way across the back.

The glue was applied liberally to the braces, but the braces weren’t correctly fitted and clamped to the back. You can see areas of glue on the braces that dried without touching the back at all.

The notches in the back graft were not cut wide enough for the braces in some places, so even with clamping pressure, the braces could not make contact with the back when glued.

I don’t want to harp on the lack of good technique too much, after all, the guitar has held together for 80 years, but it indicates that the failure of the joints was not the fault of the glue, or of poor storage of the guitar, so I have good confidence in the rest of the structure.

Continuing with the back for now, I cleaned off all the old glue to prepare to re-glue the back braces. I simply scraped the old glue off of the back. I don’t usually have help in the shop, but I did have a small helper for this job.

Here’s the back with the old glue cleaned off of the gluing surfaces for the braces and the linings. I later cleaned the head and tail block areas too, but I guess I didn’t get a picture of that.

The braces are curved so that they impart some induced arch into the back. I used flexible cauls to clamp the braces so that clamping wouldn’t straighten them out, but rather would conform the back to the curve of the braces during gluing and curing.

Now, on to the body of the guitar. Here’s the side fracture with the lining removed for access to the break . A fracture like this results in the need to glue end grain to end grain. That doesn’t result in a satisfactory joint. There’s no strength. Some sort of reinforcement is needed. Here, I’ve scraped away the wood from the inside of the guitar leaving the side very thin at the area of the fracture.

My plan is to fit this piece of plain sliced Maple veneer into the area where I’ve scraped away the wood of the Maple side.

I’ll use these curved clamping cauls to conform the veneer to the curve of the side while the glue dries. The one that goes on the outside of the guitar has a piece of butcher paper taped to it to keep it from being glued to the side of the guitar when the glue squeezes out through the fracture.

I’ll use this layer of cork between the inside caul and the veneer to be sure the veneer conforms to the curve of the side rather than the side conforming to the veneer.

I slathered the patch and the side with fresh hot hide glue and quickly clamped the veneer in place.

OK, I confess. The veneer came from a set of veneer samples. That’s why it is stamped “Maple, plain sliced”. Here it is glued in place on the side, covering and reinforcing the side fracture.

Here’s the break with the veneer glued behind it. The glue that squeezed through the break is still on the surface of the finish. I can clean that off with warm water and a soft clean rag.

Here, I’ve scraped and sanded the patch to feather edges all around, and the side and patch are smooth and contoured like the side is supposed to be. The thickness is the same in the area of the patch as the rest of the side.

On to the neck reset. The dovetail, unlike those of later Gibson flat top guitars, was cut all the way through the head block, so with the back off, steaming the joint for neck removal was relatively easy.

The neck joint came loose cleanly. Here’s another difference from later Gibsons. The color and finish were applied after the neck was glued to the body, so that bare wood shows where the neck heel was.

With the fractured side stabilized and the neck out of the way, I’ll move on to the various repairs needed on the guitar body. Here, I’ve removed any lining material that was poorly glued, loose, or damaged in the process of removing the back.

The kerfed linings are basswood, so I used bass to make new ones that match in size and kerf spacing. I glued them in with hot hide glue and clamped with cloths pin.

Here are the bright, white, new sections of lining.

The new linings are left “proud” of the level of the old linings, to be cut down level. Here’s the new lining crossing the patch that I put in the side.

A small, sharp plane made short work of leveling the new linings.

The newness of the lining is pretty obvious looking through the sound hole from the position of the player…

…so a little “artificial aging” with some aniline dyes is in order.

Likewise, some aging for the rest of the new linings and for the patch on the fractured side.

The top cracks needed some humidity to get them to close. After I had them closed and aligned, I glued them with hot hide glue worked in with my finger tips. To help preserve the repair, I put some spruce cleats on them. I “antiqued” the cleats with the aniline too.

I used heat and my favorite old Red Devil putty knife to remove the bridge.

The old bridge was badly split and distorted from string tension.

I measured the old bridge and made a replica from some old, very black ebony that I’ve had around the shop for years.

Now, with all the structural problems corrected in the body of the guitar, it’s time to put it back together. A guitar rim changes shape when the back is removed, so I had to come up with a means of holding the rim in the correct shape so that the back could be glued back on. I used a work board and these homemade “clamps” to force the rim into compliance to match the shape of the back. There’s a “prop” going across the waist of the guitar holding it to keep the clamps from pushing it in so that it would be too narrow. The screw “clamps” can be moved anywhere around the edge of the work board, so I can push the rim inward anywhere I need to for good alignment.
You can see the notches that I cut in the new linings for the ends of the re-glued back braces.

I used hot hide glue for this, so I needed to keep everything very warm in order to have enough time to put the back in position and clamp the joint. I practiced the clamping procedure several times so I knew every move and could work quickly, built a big fire in the shop wood stove to get the temperature up to about 80 degrees, and put a heat lamp over the guitar. Here’s the guitar basking in the warmth of the red light from the heat lamp waiting for me to glue the back back on.

Here’s my clamping method. It’s mostly a long rubber strip cut from a car inner tube, and also the two bar clamps and cauls for the head and tail block areas.

Some documentation of the “weather” conditions in the shop when the back was glued on. By the time of this picture it had cooled down some from the 80 degrees that it was during the  gluing operation.

Now, the back is glued on and the binding channel is cleaned up ready for the binding.

Here’s the edge of the patch that I put inside the side fracture. It is probably hard to see unless you have a pretty good computer monitor, but this view is from the back of the guitar, into the binding notch. There is the long arc of the glue joint between the patch and the remaining wood of the side.

With the back glued on and the binding channel cleaned and checked for a good fit for the binding all the way around, I taped the original binding back on the guitar. On a newer, lacquered guitar, this might not be a good idea, especially if any finish touch up was needed, but here I’m dealing with a spirit varnish finish, so I don’t have to worry about the binding cracking into little pieces from having new lacquer applied over it. Furthermore, I’ll only need a few very small, minor shellac touch ups on this guitar, nothing to cause damage to the old bindings. This is the only place where I used a modern adhesive on this guitar. I glued the binding back on with Titebond.

With the glue cured and the finish cleaned up, here’s what the binding looks like viewed from the players position.

The side fracture is still visible. Damage like that can’t be made to “disappear” with finish work, so I’m not trying to do any more to it than this.

The back binding looks and feels pretty good. Close inspection might reveal to the experienced observer that it has been off and back on, but it isn’t obvious.

Now that the “box” is back together, the replica bridge is glued on, and a bone saddle blank is prepared…

…it’s time to re-set the neck. I shaved the heel to adjust the neck angle, shimmed the dovetail joint, and heated things up again to glue the neck back on with more hot hide glue.

A new ebony nut…

…some fret leveling, and new bone saddle…

…some set up work, and this guitar is playing the blues again!