The inside scoop on the neck jig

Recently, I’ve been getting a lot of inquiries into my custom built neck jig, which I designed and built myself and am very proud of. While the idea of a neck jig has existed for a long time (see Dan Erlewine’s example: http://www.stewmac.com/shop/Tools/Jigs/Erlewine_Neck_Jig.html), I’ve found that commercial examples just don’t quite cut it. So I built mine out of .63mm steel, with 6 dial indicators and 7 neck supports. Overkill? I don’t think so – accuracy is key here, and it’s important to me to be as precise as possible.

But how does it work, exactly, you ask? Well, I’ve put together this quick little post with helpful pictures to try to illustrate what the neck jig does. First, it’s important to know that almost every guitar could benefit from fretwork. Frets need to be level with each other within a tolerance of less than .01mm in order to play clean with low-ish action, and almost no guitar manufacturer in the world is concerned with that level of accuracy when they’re building 800 guitars a day (ahem… Gibson, Fender…). Second, guitar necks don’t behave the way you think: the tension of the strings, the truss rod, and that particular piece of wood all work with and/or against each other in ways that make it impossible to guess what shape the neck will take on in various situations. You don’t want your guitar tech to just guess, do you?

Enter the neck jig. Apart from a Plek machine (which I have used, and hope to own one day), you can’t attain accurate results unless you have one of these. Here’s why: consider this beautiful pre-Ernie Ball Stingray, which is strapped into the neck jig:

neck jig

Note that it’s loaded into the neck jig in playing position. This is really important, as you’ll soon see. In this position, I adjust the truss rod to get the neck as straight as possible, and then zero out all 6 dial indicators which are reading the back of the neck. Here’s the first three closest to the headstock:

neck jig

Next, I flip the neck jig into working postion:

neck jig

Now, look what’s happened to the dial indicators:

neck jig

They’ve dropped back as much as 1.2mm! Yes, gravity sucks, and it really affects the shape of your instrument’s neck. Now, look what happens when I take the strings off:

neck jig

neck jig

The neck has dropped even further: another millimeter and a half! So, just by flipping the bass over and taking the strings off, the neck has shifted 2.5mm – how could one anticipate that without measuring it? If I were to try to level the frets without taking this neck movement into account, I’d be flying blind, and basically just guessing where the frets should be. That’s simply not good enough – I want accuracy! Fortunately, I’ve got the neck jig, which allows me to compensate for the instrument’s position and string tension, and work on the frets in real world playing conditions.

Using a scissor jack and the neck supports, I can raise the neck back to it’s original position, referencing the dial indicators back to zero, and work on the frets with a degree of accuracy that one just can’t achieve without using the proper tools.

neck jig

I’m not satisfied with guess work. If there’s a more accurate, efficient way to do things, then I’m all about it. Which was exactly the impetus to design and build my own neck jig. In my mind there’s only two ways to do something: the right way, or the wrong way. It’s a simple choice to make.

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