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Wednesday, October 12, 2016

The Luthier: Part XIV- Conclusion

It has been a few long months now since there has been any update on this project. For several of those, the fret markers were on order, but now that they have arrived, it's finally time to bring this project to a close. I posted the first part of this process a year ago last week, although the work began even about a month before that. For all it has taught me, I will be sorry for the experience to finally be over. Going into the build, I had no knowledge of building instruments, how to play guitars, anything about the design, construction, or acoustics, or even really how to use many of the tools which became common to my hands along the way. While there are several things I would have done differently now that I know better, the result has been satisfying for the expectation I had before I began.

This final post will cover my approach to the fret markers' inlay and a few final photos of the finished piece. Although nothing terribly difficult or exciting, it would be a shame to omit anything at this point. By now, it has been so long that I do not quite remember what they are made of, but it is of some natural shell material as far as I know. They have a slight iridescence to them when they catch the light just so, and serve as a nice contrast to the ebony of the fretboard. Certainly, they are a step above the bits of masking tape I had used in the interim.

First, I sorted the markers by size and roundness. I need seven of the lot, and there were only eight that were within a tolerable range of the 3mm holes drilled to inset them into. 

And here I'm referencing the drilled diameter a final time. It is within 3/100mm of the markers I set aside, which is close enough for me.

Next up, I set the bit with a depth stop. Although I tried to find a flat bottomed bit of this size, the points are spaded just enough that the holes will require a little finish work. So, I used the outer edge as a reference for how deep to drill, then set a collar on the shaft to act as a mechanical stop when the proper depth is achieved. I decided to use the lowest drilled depth as the set height because I do not want to have the markers inset below the surface of the fretboard by any amount. This way, I can slowly flatten the bottom to a depth that perfectly accepts the slight variance in height of the markers.

On a scrap bit of wood, I drilled a test hole to see if the stop needed any adjustment and get a general feel for the process. Because I am using a mechanical drill, there is little danger of over drilling or burning  a ring into the wood from friction of the collar.

Close, but still a little shallow. The marker sits about 1/5mm proud of the surface, which is perfect. The bottom of the hole is conical, so it is very easy to pare away small amounts of the high points until everything sits flush.

Now onto the actual fretboard. This was an extremely nerve wracking process, as any mistake here is on quite literally the last step in the process and perhaps the most visible and most difficult to correct. More, the location of the markers is directly over the truss rod, so there is a chance of catastrophic failure in the neck if the tension slips somewhere along the way.

To place the markers, I measured the distance between the two flanking frets and halved it, using the calipers to scribe a centreline  off of each fret to double check centre. From there, I did the same thing but across the width of the neck to ensure it was in the exact middle. For each of the markers, the dimensions were different, because the fret spacing changes as does the width of the neck.

And here is the moment of truth.

Once drilled, I chose a specific marker to pair with the hole. Changing it later would result in imperfections in the fit, as they are all slightly different. Using the smallest chisel I have, I slowly cut away a flat platform for the marker to rest on.

Leaving it there temporarily so as to keep track of which marker goes to which hole, I moved onto the next, then repeated the process for the 6 remaining holes.

On the 12th fret, I placed a double marker to signify the octave fret. Spacing them was a bit of trial and error, adjusting by a few fractions of a millimetre until the size of the markers balanced the width of the neck and the spacing between them.

Once all seven holes were drilled and cleaned, I used a small amount of the same hard PVA glue to hold them in place.

In the above picture, the 7th marker placed two below the 12th fret pair was not yet in place, as the frets became too close together for the drill collar to work properly. After the others were affixed, I went back and carefully did it freehand.

A day later once the glue cured, it's time to begin cleaning the ebony of all the marks left behind by the inlay. In the end, I only went to 600#, as the grain of the ebony is porous enough that the 1500# made no difference.

Using a variety of hard sanding blocks, I sanded between each of the frets until satisfied with that particular grit, then moved on to the next.

A few of the markers had slight areas of concern that needed to be addressed, whether proud or recessed by a hair's width, so the rough grits helped speed up the process significantly. In the end, everything came out dead smooth.

The next step was to re-string the thing and finalise the placement of the bridge. This dramatically effects the tuning when playing anything other than a completely open chord. The bridge acts as a constraint for harmonic length of each string, so it being forward or backward of where it is supposed to be, the pitch will be either sharp or flat when playing off any of the frets.

Fortunately, it is a fairly simple process to figure out. The short of it is, the 12th fret needs to be half way between the nut (neck) and bridge (body). Put another way, the length of the strings needs to be twice as long as it is from the nut (neck) to the 12th fret. 

After a few slight adjustments, it's all set. If I come back later and install a set of pickups (some technical challenges involved that may prohibit it), I will mark a line on the body itself to ensure that the harmonic length is exact and easily repeated when the bridge is removed and replaced.

And that's it. A year is both an incredibly long time and incredibly short, considering the constraints of where this project was born.

This is the first real time I have worked closely with wood, the tools, and the skills that draw the two together. As is likely evident throughout the 13 other posts of this project, there is much that I do not know, much that I have learned, and much that I will be able to use going forward. This instrument, although I largely have no idea how to play it, represents something of a great step towards a direction that holds a profound personal meaning. Perhaps one day I will return to world of the luthier, in either to create similar instruments or others that I know little about beyond the allure of their sound and their past. And until then, it's time to learn the other side of this craft and make music.