Kohei Fujii Guitars

Kohei Fujii Guitars

Sunday, February 28, 2021

Ready for the spraying session

      Epoxy filling and sanding sessions were completed. After the final sanding with 400-grid sanding paper, Alcohol thinned epoxy was applied. This Alcohol thinned Epoxy makes even finishing color. During the final sanding session, epoxy filler should be removed completely except wood pores. However, some locations, remaining epoxy fillers are there. This un-even epoxy filler distribution makes uneven color distribution. To avoid the uneven color, the thinned epoxy courting is required.

     Next week, I will spray a Water based acrylic lacquer. In March, here in Northam California is worm enough for the spraying sessions. 

Sunday, February 21, 2021

Final sanding and Epoxy Filling

      Final sanding is completed. Finger board is masked with a masking tape. Bridge portion on the top is not masked at this moment. The bridge portion will be masked after the Epoxy application and sanding session. If the masking tape was applied before the Epoxy, the surface flatness is pretty bad, due to the masking tape thickness. Also, I will almost completely remove the Epoxy filler from the spruce top portion. I will not remove the Epoxy filler from the binding and Rosetta portions on the top. So, the masking tape for the bridge should not be applied at this moment. 

     I have been using the System three Epoxy with Silica thickner. I applied a first coat of the Epoxy filler. System three requires approximately 24 hours for the sanding session. I am expecting that this guitar requires three sessions, because this guitar has Brazilian RW, Honduras RW, and Madagascar RW. Those materials are large pored materials. So, I will spend relatively long time for making the foundation for the final coat apply. While waiting the Epoxy filler cured, I will make the bridge.

Sunday, February 14, 2021

Fret-wire install and neck shape

      For the custom MD project, I did the fret-wire install and the neck shape. This guitar has the fingerboard binding. For the fingerboard with binding, I needed to cut fret-wire edges. There is a custom tool to remove the fret-wire edges. This is an amazing tool. It makes the fret-wire work so first and high quality. I usually remove fret-tangs approximately 80%. To make good bonding to the fingerboard slot, I use yellow glue for the fret-wire install. Fret-wire tangs are way too large. If I install the fret-wire without tang modifications, fret-wire works as a large tapered pin in a fingerboard slot. This makes a reverse bow shape for the neck. Traditional classical guitar makers have been using this technique for the neck reinforcement. However, modern neck design is a different story. Modern neck has two carbon fiber rods and steel truss rod. Neck itself has more than enough robustness against the strings pull. So, I remove the fret-wire tangs to avoid the unwanted fingerboard deformation.

     Before install the neck to the body, I did a rough shape for the neck. Now, I completed the final shape for the neck. I also completed the volute shaping. This neck has an Ervin Somogyi style volute. Although my neck has a completely different headstock design, Erving Somogyi style volute works good for my neck design. Next week, I will have sanding sessions, and hopefully, I can move to an Epoxy filler apply process.

Sunday, February 7, 2021

Truss rod and Finger board install

      I installed truss rods and a finger board. Graphite truss rods are extended over the neck joint to obtain better connection between the neck and the body. I always install a wood cover over the truss rod. Wood cover prevent epoxy contamination to the truss rod thread. Also, the wood cover over the truss rod enables to level the neck surface. This configuration makes a perfect bond between the neck surface and the finger board. I have been using Epoxy for the fingerboard assembly. Unlike the Epoxy, yellow wood glue is the water base, and the water from the glue extends the finger board. As a result, the neck always creates reverse bend (anti bow shape). I want to very precisely control the neck angle and the neck bend to make the lowest possible action setting. To avoid unwanted neck bend, I have been using the Epoxy for the fingerboard install. I also did the fingerboard radiusing for the 20' radius before install fingerboard. 

     Next week, I install fret wire, and then I will have sanding session. Then, this guitar will be ready for the finishing work.

Sunday, January 31, 2021

Neck install

     I made a neck installation work. This is a mortise joint with two wood dowels. This is the identical method as Erving Somogyi has been using. I had been using the bolt on neck joint. Due to the additional weight penalty, I do not use the bolt on joint any more. I switch over to the mortise joint. Mortise joint is very herd to do the neck re-setting work, if it is required in 30 to 50 years later. However, my guitar has carbon fiber rod bracings inside the guitar body. My guitar do not need the neck re-setting work permanently. 

   Before glue the neck to the body, I will take a neck shaping work and fingerboard radiusing work, Once glue the neck to the body, I need do heal cap install, truss rod channel extension, truss rod install, and fingerboard install. There are many detailed processes to complete the MD making project.

Sunday, January 24, 2021

Beveled armrest and Scrolled edge

Body making complete. I installed a Cocobolo veneer over the beveled armrest. Thickness is approximately 1.5mm. Thicker material is more challenging to install seamlessly. However, the thicker veneer makes more serious look. Also, thicker veneer matches well with the binding material. I very carefully bent the Cocobolo veneer, and installed using the Epoxy with African blackwood sanding dust. I also installed the scrolled edge on top of the cut-a-way, Material is 1/4" diameter Walnut dowel. Scrolled edge was also installed using the Epoxy with ABW sanding dust. I lightly sanded with 220 grid for entire body. Now, the body and the neck are ready for the jointing. Next week, the neck will be installed to the body.


Sunday, January 17, 2021

Binding install

 I did binding install work. This MD has the Madagascar RW binding. Mad. RW is a very easy material for the bending. As log as it heat enough, the Mad. RW bends like a rubber. However, this material is very herd and strong for protecting the guitar body. Also, this material has relatively few pores. So, the finishing work is also easy. I spend a lot of time for binding channel cleaning and fitting. Also, I spend a lot of time for the binding material bending and fitting. Precise fitting work makes a huge difference for the binding installation quality. Therefore, the binding installation is a very time consuming process. Next step, I will install a scrolled edge at the top of the cut-a-way. I found a nice walnut 1/4" size dowel. This material has nice matched color for the Madagascar RW binding. So, I can make the scrolled edge for the Mad. RW binding.