A good friend of mine called me one day and said that he broke his guitar. It fell down and the headstock snapped under the string tension. I imagined this as a huge mouse trap with a piece of wooden headstock flying to catch whoever broke the guitar. Given that my friend plays a lot and he was having a gig in a week it was a good opportunity to try repair something new.

Usually a product of some kind has a number of possible ways it can break. These ways are called failure modes. The most common for guitars is a string snap. A bit less common is structural failure of a headstock - head of the guitar holding strings.

The patient in this case is Ibanez Talman TCY10 Acoustic-Electric Guitar Black.

In the photo you can see a red line representing the place it snapped.

The last photo is the guitar after the repair.

Step 1: Plan Ahead

As with any repair, it usually is unique and depends on a number of aspects. In this case the headstock shown on the photo had only one clean enought break line with no extra chips of wood. To make a good repair you would need to remember a 6-P rule: "Proper Prior Preparation Prevents Poor Performance".

List of materials:

Wood glue
2in1 Epoxy glue / Gorilla glue
Furniture metal braces
Cloth
Tape
Spray Paint
Spray Lacquer
Sanding paper
Marker
Dust mask
Gloves
Safety goggles

List of tools:

Screwdriver
Pliers
Dremel
Sander
Bench Vice

Step 2: Clean and Glue the Headstock

Before you start gluing the headstock you have to make sure all the surfaces are ready. The wooden surface should be dry and clean with no oils etc. If this step is not done properly, then the following ones will be less useful.

Start by taking off all the parts that are connected to the headstock. Make sure to mask the other areas of the guitar with tape / old packaging materials not to scratch the guitar accidentally.

When applying the glue make sure to wear gloves as it is chemicals after all and can irritate the skin. A piece of cloth is a good idea to minimise potential mess.

Another aspect to pay attention to is the way you compress the parts being glued. In my case the breaking line was at about 45 degrees to the face plane of the headstock and a simple clamp could not hold it in place. I had to come up with layers of wooden planks and angles to clamp it all securely.

After it is glued you could store the guitar in its case until the next step.

Step 3: Prepare the Slots for Reinforcement

Time to reinforce the headstock!

The main idea behind this instructable is to add metal braces to both sides of the glued headstock to make sure it doesn't break again. For this you need to mark the zone of the headstock you would need to take away with dremel, prepare the braces and cut out the slots. The slots should be a bit deeper than the thickness of the plates. Try not to take out more material than needed.

It is very important to wear the safety goggles and dust mask when using dremel.

The brace on the back is slightly curved. This could be done by puttng the brace in the bench vice and accurately bending it using pliers, bare hands or someone else's bare hands. The surface of the metal plates could also be made a bit rough to make sure that the glue sticks to it well and it has in general more contact area. The braces I got were originally made for connecting pieces of furniture, hence the holes. These holes help for the glue to wrap around and air to escape.

Step 4: First Batch of Epoxy Glue

The first batch of epoxy glue is used to fix the metal brackets in the place strengthening the structure. To successfully glue you would need to carefully follow the instructions on the package. Most of the 2in1 epoxy glues have a short enough initial cure time. Usually, whatever the package says, I add a couple of hours to the final cure time to make sure that it definitely works.

Remember: The two active components need to be mixed very well.

For information: Gorilla glue instructions

Step 5: Sanding N.1

After the first epoxy is applied, the initial sanding is done. This is to give space for following layer. The best tool I found for that was a dremel with a sanding tip.

It is very important to wear a dust mask for safety as the small particles sanded off could easily mess up the lungs.

Step 6: More Epoxy Glue

Time to fill all the other holes and surface irregularities. The same rules apply, the surface should be dry and clean of any residual dust particles. Mix a new batch of epoxy glue and apply in a way to have all the surfaces you worked on covered in extra, that you could take away later.

Step 7: Mid-repair NDT Test

NDT stands for Nondestructive testing. As we are done gluing, it is time to test if it works at all. We do not go into any sophisticated measures. What we do is simply put on the strings on the guitar in the proper tension and strike some of our favourite chords. The guitar seemed to withstand the tests, but now it is kind of ugly.

Step 8: Cosmetic Repair Starts: Polish the Surfaces

It's time to make the guitar beautiful again. I applied some thicker tape for guitar's safety to allow accidental slips of the sander. This step is quite straightforward, the guitar is sanded into the original shape using sander or sanding paper on a wooden block. This step is the last opportunity to make the final shape right.

It is very important to wear a dust mask for safety as the small particles sanded off could easily mess up the lungs.

Step 9: Paint the Base Colour Layer

I had some black matte spray paint can lying around and I decided to use it to hide the metal inserts, epoxy and the evidence of this repair. At this point the time was pressing and I decided not to polish it with fine sand paper after painting. This could have made the surface a bit less rough. Overall most of the signs of the repair were hidden.

Step 10: Paint the Layer of Gloss Finish

As the final step of repair I used gloss laquer spray. It added a bit of gloss to a very rough surface and I presume added to the surface resistance a bit. Sure it does look weird to have a step in surface appearance.

Step 11: Final Notes & Lesson Learned

Final Notes:

The result of the quick repair is shown on the photos. There are some visible surface irregularities - bubbles and not ideally flat areas.

Excluding the tools, overal cost turned out to be around 30 EUR / 33 USD with some materials leftovers.

The feedback from my friend was that having that rough area underneath the first fret added a bit of support for the hand and helps when the palms are sweaty :) The gig went well.

Lesson Learned:

Take more process photos
Reinforcement plate slots to be deep enough
The number of epoxy glue bubbles could be minimised by mixing techniques and may be a glue solution that get fewer bubbles.
Put more time into polishing the surfaces.
Get the right type of paint for the job (not matte for the glossy guitar)
Masking tape should be applied evenly to give a nicer look if the boundary between paints will be visible.

Useful links on repair of guitar headstocks in various states of destruction: