Neck Geometry...

Note to self...

Everyone that knows me, knows that I'm a stickler for details when I care about something.  I love to study, over-analyze, and to ask "why?".

Neck set geometry is critical to a successful build.  In my mind, all of the variables associated with the neck set, in relation to the top, are the most critical of the build.  Anyone can make a guitar beautiful to look at but I also want to make a guitar that will last a lifetime... one that won't have structural issues 5 years down the road - for example, neck resets, etc.

The top of an acoustic guitar is not ideally flat in my mind.  There's no structural integrity in a flat, thin piece of wood.  Many well-known brand names have built flat top guitars, but geometrically I have to ask - are they really successful builds?

Even though this is my first build, I'm a sucker for knowledge... I've read, and studied, a ton of what is available and think I'm starting to come to the newborn stage of an understanding (obviously, still a "work in progress").

The question is:  Can I take this theory and transfer it to a piece of wood successfully?  Realistically? Probably not, precisely exact, on my first build...

What I've learned - so far... (keep in mind, I'm still new to this).

The strings of a guitar resonate differently through a series of variables on the guitar - the frequency generated from the effect on the top plate are realized by what one hears audibly.  When a string is plucked, it vibrates - what controls that vibration is the action of the string, which is affected by the nut, the finger board, the top, the neck angle, the bridge/saddle, etc.

A slightly "domed" top plate versus a "flat" top plate wins theoretically every time in my mind. Adding the slight dome shape to the top of a guitar adds stiffness to the top.

- The stiffer top equals a top that will more efficiently withstand 185-200 pounds of string tension reliably and last longer - with less tendency to warp, crack, etc. under tension.
- The stiffer top can also mean a thinner top - which may mean a more resonant top plate.
- A stiffer top can also use lighter bracing of the top plate.
- The dome shape will resist deflection of the bridge to roll forward under string tension and accomodate the neck angle.
- The dome shape also will hopefully resist future neck sets.
- A domed shape resists the caving in or rolling up effect (due to lack of humidity, tension, etc.) which, in turn resists cracking and seam splits.

All of this adds up to - geometric madness.

After thinking about the above, I've tried to think about and decide on what my goals were.  My goal is to take this information and learn how to make a guitar that will sound great but - withstand the mildly abusive guitar player (like myself).  I don't want to build a guitar that 5 years down the road I'm going to have to repair cracks/splitting, constantly having to adjust the action, or worse - do a complete neck reset on.  I want a guitar that I can play, one that will sound good, and one that will endure my heavy hand and mother nature.  If it also looks good then that's the icing on the cake.

So - that being said...

Here are some notes that I'll need for not only this build, but for any future builds.

[1] The goal is to build a top that is as light as possible yet stiff enough to withstand the 185-200 pounds of string tension... and, still resemble that shape 5-10 years down the road!

[2]  Using a straight-edge, the height off of the top plate at the bridge location - in relation to the neck plane (without the fingerboard), should be 0.090".  With a 1/4" thick finger board I should shoot for between 5/16" (0.3125") and 3/8" (0.375") height off of the top plate (with fret board - 0.250" + 0.090" = 0.340") at the location of the bridge.

This will provide for my neck angle (between 1.5 and 1.75 degrees) in relation to the top.  It will also ideally provide great action and provide effective drive from the strings to the top plate of the guitar.  I want to effectively drive the top plate without causing a dampening effect (via the bridge, saddle height, etc.).

[3]  My saddle height should be between 0.090" and 0.125" (1/8").  Any less than that and I will start to lose my break angle of the strings (from the saddle to the back of the bridge).  Too low, and the strings will tend to buzz and I'll lose volume/tone because the strings won't be efficiently driving the top.  If the saddle is too high (in an attempt to over-correct an over-set neck) the bridge will tend to want to roll forward over time under tension.

Ok - there's my outline... now - can I transfer theory to wood?  We'll see.

Again - I'm not the C. F. Martin company building 70,000 guitars per year, but... I don't want to put my name on a guitar that 5-10 years down the road is going to come back to me for neck resets, etc.

[1]  I can't afford it - Amy would kick my butt, and...
[2]  I'm just kinda goofy that way.  I want to do it right the first time.

One of the lessons I've learned for life in general - "If you don't have time to do it right the first time, when will you find time to come back and do it over?"


Anyway - like I said:  "Note to self..."