Portland Guitar Co.

Designing and Building
Custom Handcrafted
Guitars, Ukuleles
and Accessories

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

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Engineered Braces | Tilt Action Neck | Split Saddle Bridge | Split Saddle Nut


Portland Guitar Pretty Good Intonation (PGPG) System

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

Finished Build

Small Jumbo Model Cutaway
JMC 1.2.22

Zircote Body
Bearclaw Sitka Spruce Top
Mahogany Neck
Ebony Fretboard
Snakewood Binding and Bridge
User Adjustable Tilt Action Neck
LR Bragg Dual Source Pickup

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(102) July 31, 2008
Now I am finishing up the shape of the heel block.  I am using the cutaway form with a piece of sandpaper attached to get the shape close to its final shape.

(103) July 31, 2008
And then I use the idler pulley on the belt sander to fine tune the shape.

(104) July 31, 2008
The result is a well shaped heel block.  I will also chisel out a recess channel for the lower kerfing to complete this piece.

(105) July 31, 2008
Here I am gluing the heel block to the right side of the guitar.  I use many clamps to ensure a firm joint.

(106) July 31, 2008
After the right side has dried, I glue the left side to the heel block.

(107) July 31, 2008
And then finally I glue the end block in place.

(108) July 31, 2008
A picture of the rim all glued up.

(109) July 31, 2008
If you take a look at a steel string acoustic guitar you will notice that the back and top of the instrument are not exactly flat.  Each instrument maker forms the top and back into a bowl shape to a greater or lesser degree.  Usually the back has a deeper bowl shape than the top, and some guitars truly are flat topped  To accomplish this we use bowl shaped form, one for the back and one for the top.  In this picture we can see the shape of the form for the back.  This form has a shape that is equivalent to a bowl with a 14.25 foot radius.  Shaping the top and back into a bowl increases the stiffness of the the plates while allowing the thickness and mass of the plates to be reduced.  In the physics of the guitar, stiff and light are generally desirable traits.

(110) July 31, 2008
Since the back and top of the guitar are shaped like a bowl, the rim of the guitar must be shaped to match the bowl as the rim follows the shape of the guitar.  If you think about this a bit you will come to realize that the final shape of the sides is really quite complex.  If you look back to picture 14 you can get a sense of the convoluted shape of the side when it is laid out flat.  This is especially true of the cutaway side.  To match up the sides to the front and back plates, I place the rim into the side form and put a piece of sandpaper on the back and top form.  Then using a bit of elbow grease I sand the rim down until the rim comes in contact everywhere with the form.  This gets the shape of the rim right and sets the angle of the shelf at the same time.  Here we see the top in process.  Where there is no sawdust on the form the sides are not yet touching.  The final bit of adjustment come in getting the width of the sides symmetrical on the right and left sides.