The Neck Angle

The need for a neck angle seems to cause quite a bit of confusion amongst beginners. One question that pops up again and again is "Do I have to use a neck angle with...?" The answer to that is NO. you never HAVE to use a neck angle. You may want to for esthetic and, to a lesser degree, comfort reasons, though. OK, now that I probably lost a bunch of you, let me start the whole thing from the beginning.

The What and the Why

First of all, what is a neck angle? If you have ever played a Gibson Les Paul, you have played a guitar with one. The neck is set into the body at at slight angle, tilting backwards with respect to the top of the guitar. The angle varies between a fraction of a degree and a few degrees. So, why do some guitars have a neck angle, while others do not? For a guitar to be playable, you need to make sure that the action is good, that the strings run parallel to the fretboard at a good distance, not too far and not too close. You can adjust the action somewhat my raising or lowering the saddles, but the strings need to be roughly in the right place to start with. This is controlled by the pitch, or angle, of the neck. For the strings to form a straight line from the bridge to the nut, you have two choices: a neck angle or no neck angle.
Gibsons and other guitars, on the other hand, have angled necks. On a Les Paul the fretboard is fitted flush with the top, and so to achieve the desired action the neck is angled backwards. The carved top partly disguises this fact, since it is shaped to follow the angle precisely (Take a look at one to see what I mean.) The slight neck angle makes the guitar marginally easier to play, since the neck is tilted towards the body, and the hand doesn't have to go as far out. However, this is a very subjective point, and some people may not notice much of a difference (I don't really notice.) The fact that the neck is glued in makes it impossible to fiddle with the neck angle after the fact, short of removing the neck and resetting it or, more probably, making a new one! Please note that truss rods CANNOT fix problems that arise due to miscalculated neck angles!
Gibsons and other guitars, on the other hand, have angled necks. On a Les Paul the fretboard is fitted flush with the top, and so to achieve the desired action the neck is angled backwards. The carved top partly disguises this fact, since it is shaped to follow the angle precisely (Take a look at one to see what I mean.) The slight neck angle makes the guitar marginally easier to play, since the neck ski tilted towards the body, and the hand doesn't have to go as far out. However, this is a very subjective point, and some people may not notice much of a difference (I don't really notice.) The fact that the neck is glued in makes it impossible to fiddle with the neck angle after the fact, short of removing the neck and resetting it or, more probably, making a new one! Please note that truss rods CANNOT fix problems that arise due to miscalculated neck angles!

How to Calculate it

Now that I've explained why you would want to use a neck angle, let me explain what factors affect its value. They are:

• Bridge Height: the height of the bridge with the saddles lowered as far as they will go. If your bridge has a built in radius, take the highest point.
• Fretboard Thickness: The thickness of the fingerboard at is thickest point, including the height added by the frets
• Distance from bridge to Beginning of Angle: Most often this is the same as the distance from the bridge to the end of the fingerboard, but you may choose to begin the angle at the edge of the body, for example, instead of at the end of the fingerboard, which will affect the angle.

To calculate the neck angle, we set up the situation where, when the bridge saddles are as low as they will go, the strings are just touching the surface of the fingerboard. If you don't want to angle your neck, this makes it pretty simple, since you just measure the height of the bridge, and make sure the fingerboard is at that height when the neck is mounted. Its a little more complex if you decide to do for the angled neck. You essentially have two options; First of all, you can have the neck angle start at the end of the fingerboard, like on Les Pauls. This will mean that the neck will lower itself into the body until it reaches the end. Les Pauls disguise this because they have a carved top. If you don't have a carved top, this will probably look odd. For you, the angle should start at the end of the body, and the part of the fingerboard that extends over the body will be slightly proud of it. As you can see, the decision of where to start the angle will affect it directly.

Now on to finding your neck angle. The easiest way to do it depends on how comfortable you are with basic trigonometry (the Tan function). First for those who have forgotten how to use it completely:

Draw a horizontal line on a large piece of paper. This represents the top of your guitar, viewed from the side. Mark off a length representing the distance from the bridge to where you will start your angle. At one end of this line, draw a line perpendicular (90º) to the first with length equal to the minimum height of the bridge minus the height of the fingerboard (Height Bridge - Height Fingerboard). Connect the top of this line to the other end of the first line, and you have a triangle. The angle this last line forms with the first line is the required neck angle (see figure)

Now, for those who remember their trigonometry, its a bit simpler. I recommend you jot down the same measurements and draw the triangle, though not necessarily full scale, just to make sure you are using the correct numbers. The formula is essentially the following:

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