Portland Guitar Co.

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and Accessories

Portland Guitar Co. | Portland Oregon | Contact Jay Dickinson-503.245.3276 | jay@portlandguitar.com

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Portland Guitar Pretty Good Intonation (PGPG) System

Short Version | Introduction | Intonation Errors | Analysis | PG Approach | Comparisons | Conclusion

Finished Build

Small Jumbo Model For Joe E.

JM 1.5.28 Small Jumbo

16" Lower Bout
Figured Walnut Body
Sitka Spruce Top
Ebony Fretboard
User Adjustable Tilt Action Mahogany Neck, 26" Scale Length
Maple Binding, Bloodwood Striping

Page 1

(1) 14-Sept-09
This set of figured Walnut comes from a the crook of a tree that was cut in the Willamette Valley in the middle of the last century and has been sitting in the shop of a local woodworker since then.  I was lucky enough to come across it and give it life as a guitar.

(2) 14-Sept-09
In these pictures the wood has been wetted down to bring out the figure.  Beautiful!

(3) 14-Sept-09
I am starting this guitar by preparing the edges of top boards.  I want the joint to be nearly invisible, so I use this tool that holds the pieces vertical while sanding the edge perpendicular to the top.  I reverse the orientation of the second piece when I sand it to match any variation in the surface angle.

(4) 14-Sept-09
I use this joining machine that uses a set of wedges to force the two pieces of the top together while it holds the top down flat.

(5) 14-Sept-09
Here we see the joined top with the outline of the guitar drawn on it.

(6) 14-Sept-09
I do the same thing for the back pieces.

(7) 14-Sept-09
In this picture you can see the center strip of flamed maple that has been inserted between the two halves of the back.

(8) 14-Sept-09
A picture of the joined back.

(9) 14-Sept-09
And a close up of the joined back.

(10) 14-Sept-09
Next I use my drum sander to dimension the thickness of the side pieces to about 90 mils.

(11) 14-Sept-09
And these pieces go into the bending machine.  You can see here the heating sandwich that has a heating blanket in between two pieces of flashing with the side lain on top and another piece of flashing on top of the wood.  The top piece of flashing has holes in it to allow me to squirt water on the wood.  The flashing helps to support the wood while it is bending and helps to spread the heat evenly.  The water acts as a thermal conductor and prevents the wood from getting scorched.   I heat the wood up to about 200 degs F or until the wood becomes pliable.

(12) 14-Sept-09
When bending the wood the first thing I do is use the central tower to press the waist into shape.

(13) 14-Sept-09
And then I use the front roller to bend the upper bout.

(14) 14-Sept-09
And then the back roller to bend the lower bout.

(15) 14-Sept-09
After the wood has taken its shape I remove the top piece of flashing and cook the wood at about 120 degs until the wood will hold its shape.

(16) 14-Sept-09
And in the end we have a couple pieces of funny shaped wood.

(17) 14-Sept-09
In this picture I am putting a bezel on the kerfing.  I use a reversed kerfing method that puts the slots next to the back with a solid strip of wood held about 1/4 inch away from the sides.  This will result in a system with a gunnel around the rim of the guitar and sides that are very stiff. .... Stiff is good!

(18) 14-Sept-09
Here we a close up of the shape of the kerfing.

(19) 14-Sept-09
The kerfing goes into the bending machine to give it the shape of the sides.

(20) 14-Sept-09
A picture of the bent kerfing.

(21) 14-Sept-09
I have carefully drawn the outline of the guitar on the side blanks and in this picture I am trimming the excess from the sides.  I leave about 1/8 of an inch excess.

(22) 14-Sept-09
With a little imagination you might start to see the guitar.

(23) 14-Sept-09
In this picture I am laying out the kerfing in the sides to make sure the kerfing goes into the right place.

(24) 14-Sept-09
While the side is in the form I glue the kerfing into place using about fifty clamps.  This process insures that the sides take the shape of the form. All of those clamps are pushing the side piece into shape with a lot of force.  If each clamp produces a force of ten pounds that would result in a total force of about 1/4 ton.  At the same time the kerfing is being pressed into the sides so the glue joint is solid and with out any gaps.

(25) 14-Sept-09
And when all of the glue is dry the sides come out of the forms and they are very stiff and will hold their shape.  The blue tape is in place because I will remove the kerfing in those areas and I don't want the kerfing to stick to the sides.  This is where the heal block and the tail block will go and these will hold the sides together.