The base of the neck has a series of loose wood chips that if not fitted properly, will cause a misalignment, leaving a gap at the seam of the two pieces. After gluing the neck in place the seam must be sealed, then I will proceed to sand the base of the neck and re-varnish it. The smaller the gap between the two joint pieces, the better to seal and cover the seam.
Before gluing the neck in its place there should be a number of remedial measures to make the work easier in subsequent steps, which would be surface preparation and varnish coating.
Neck Base.
In this picture you can see loose pieces of wood.
From this angle you can see that the fibers closer to the instruments top are holding the piece of wood.
The pieces of wood are out of place. To achieve a better matching of the parts the little bits must be brought back in place. I put a little Cyanoacrylate glue on the outside along the crack as I held the piece of wood in the correct position with my finger. I applied the glue on the outside because I did not want to seal the grain of the wood in the interior area with any residual glue .
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Materials for separating the fingerboard from the neck:
A-Rigid stainless steel ruler
B-Thin-bladed knife
C- Rigid Spatula
D- Heat Pad
E- Alcohol
The glue that it is used for most acoustic stringed instruments is called Hide Glue. It must not be confused with Rabbit Skin or Plastic Resin Glue. All these are mixed with hot water but only the "Animal or Hide Glue" is used for musical instruments because it allows the glued pieces to be disassembled in need of a repair. By its nature, the "Hide Glue" tends to come off with extreme heat and weakens in the presence of alcohol. So, that is why it's never good to leave a stringed instrument in the car trunk.
Furthermore, the "Plastic Resin Glue" is resistant to solvents and heat, making it impossible to separate the wood. For carpentry applications this glue is highly recommended, but not for musical instruments. The adhesives should always give the Luthier the option to take off the parts in case something goes wrong in the manufacturing/assembly or in future repairs on the instrument.
Heat is applied with the pad
The temperature of this Heating Pad can go above 170 degrees Fahrenheit. It is very important that the pad covers the entire area to be detached and that it is well adjusted so that heat is concentrated and penetrate well into the wood. I set mine with two nylon strings. The pad should be left to work at least for 40 minutes to an hour.
The heat is separating the fingerboard
The two ends in the fingerboard are the areas to come off first. Once it starts to separate you have to make way with the tools and cover the neck with the Heat Pad so that heat continues to penetrate and detach the pieces.
Use the knife to make room for the other tools while still applying heat.
The spatula is used to maintain an open space to let heat enter to the center of the fingerboard. Slide the knife on the gap without forcing it and let some minutes pass by.
When I was near the end I realized that the heat was no longer separating the fretboard so I inserted the metal ruler and drop a little of alcohol between the pieces to soften the glue, then I apply heat for a few more minutes. After the alcohol was applied, I inserted the spatula as seen in the previous picture but on one side of the fingerboard and separated the parts with a slight pry motion. Under no circumstances you should force the knife or hammer any of the tools to loosen or separate the parts. Doing so could damage the wood and loose large pieces of fiber that could remain attached to the glue.
Here are the two separate parts. You can see the glue residue and wood in both pieces. It is normal for a bit of wood fibers remain in both parts.
On this forum is an example of a similar fingerboard separation method but using a professional heating pad like the one in this photo In my case I use the resources I had at hand and saved some money in the process. ;)
After the pieces were separated I applied a little of "Cyanoacrylate" glue in the crack that I saw in the neck. This is to hold it in place.
The next thing will be to glue the neck in place, make a dowel for the reinforcement and drill the hole in the base of the neck to install the dowel.
End of Part 2
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