Portland Guitar Co.

(131) 16-Oct-2009
Now I am setting up to apply the finish.  I have a set of curtains that define a spray booth for this purpose.  Inside the curtained off area is an air filter that recirculates the air filtering out most of the airborne dust inherent in my shop and the over spray from the spray gun.  I use a water based polyurethane that is environmentally benign and is easy to repair should it be necessary.  I am often asked how many coats I apply.  The answer is on the order of twenty-five or thirty, but this does not tell the real story.  What is more relevant is that in the end the finish is three to five mils thick.  In this picture I am preparing the neck by masking off the fretboard.

(132) 16-Oct-2009
The process of finishing involves apply one or more layers of lacquer, letting it dry and then sanding off the high spots.  Then a new layer of lacquer is applied that fills in the low spots.  The new layer is then sanded once again removing the high spots.  This process is repeated until the high spots and low spots are leveled out and there is enough lacquer to protect the wood underneath and is able to be polished to a high gloss.  I use a balloon to plug the sound hole.

(133) 16-Oct-2009
I use a fixture that holds the guitar and  allows me to move it around giving me access to all of the parts.

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A view of the back after a layer of the lacquer has been applied.

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A closer view.

(136) 16-Oct-2009
A picture of me leveling the surface with a soft 300 grit sanding block.  After the last layer of lacquer is applied and leveled I let the finish cure for ten to fourteen days.  The lacquer is dry to the touch after about twenty minutes, but it is very soft.  During the curing period the lacquer shrinks and hardens.  After the finish is cured I start to put a high polish on it.  I do this by using a special high quality sanding cloth called Micro Mesh.  This process starts out with a 1500 grit cloth and end up with a 12000 grit cloth.  During each step I remove the scratches introduced by the previous step until the scratches are so fine you can't see them.  In the end I use a buffing wheel to bring out the final high gloss.  

(137) 16-Oct-2009
Side-Bar... I had a guest come through my shop last week and he got excited when he saw the rosette on this guitar.  He pulled his hand out and showed me the ring he was wearing.  He said the pattern was a traditional Hopi Indian design.  I came up with this symmetrical interdigitated wave design over many years of doodling during boring class lectures.  When Will asked for a Celtic Triskle based theme for his guitar I thought that the wave based rosette would make a good compliment to the triskel in a triskel contra-rosette.  Ultimately I plan on manufacturing this design into purfling strips that will outline the edges of my guitars.  I would like this design pattern to be a signature pattern for Portland Guitar.  I have yet to figure out how to easily manufacture these purfling strips.

(138) 16-Oct-2009
Since this is the first time building a base guitar I felt is was important to experimentally determine the amount of compensation that would be necessary for each string to be well intonated, i.e., remain in tune as notes are played up the fretboard.  To do this I have constructed a dummy guitar body that will accommodate the guitar neck and allow me to string it up.

(139) 16-Oct-2009
Once the dummy guitar is strung up I can move the saddle blocks until the octave is in tune with the fundamental.  I can then measure the scale length for each string.

(140) 16-Oct-2009
Just a picture of the assembled guitar after the final polish has been applied.

(141) 16-Oct-2009
Now that the finish has been applied I turn my attention to the bridge.  But first I have to figure how I am going make the adjustable bridge Will has asked for.  An adjustable bridge will allow us to set the saddle blocks in the proper position to get the correct intonation if the type of strings are changed.  The intonation of a guitar depends on the type of strings that are used, the height of the strings above the fretboard, i.e., the action, the tension that is applied to the strings, and surprisenly the way that the guitar is played.  In this image I am chiseling out a channel that will house the movable saddle block.

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Here is a picture of the saddle block in its channel.

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I have to route a channel for each saddle block.

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And then I drill the holes for the bridge pins.

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Once all of the important holes and channels are installed in the bridge blank all I have to do is sand away everything that doesn't look like a bridge.

(146) 16-Oct-2009
In this picture I have applied a decorative face plate that compliments the headstock veneer.  I have laid out the bridge assembly on the top of the guitar to see how it will look.

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Another view of the bridge assembly.

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Another view of the bridge assembly.

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In this picture I have laid out the bridge assembly in profile showing how everything fits together.  The blue line is representative of the spruce top, and the green line is representative of the bridge plate.  The bridge plate, in this case made of Indian Rosewood, performs several functions.  One is to protect the Spruce top from the ravages of the end ball on the string.  Another is to reinforce the area under the bridge helping to distribute the torque that is applied to the top of the guitar from the strings.  And finally the bridge plate helps to acoustically couple the bridge to top.

(150) 15-Dec-2009
I carefully mark out where the bridge goes.

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I use a very sharp new exacto blade to mark the bridge position.

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The bridge position.

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I use my dremel router base to remove the finish from where the bridge goes.  I want a a wood to wood connection between the bridge and the top.  This will help insure the bridge doesn't pull off during its life.

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I use a chisel to remove the finish around the edges.

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And then I glue the bridge on to the top.

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Will A. and his new bass guitar.

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Will A. and his new bass guitar.

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Will A. and his new bass guitar.

(159) 15-Dec-2009
Will A. and his new bass guitar.