Notched or non-notched straight-edge
Recently, I had an email from someone having trouble with their neck setup and they reached out for help. They wanted their neck set up almost perfectly straight but were having some problems getting things to sound and play correctly after they set the relief where they wanted.
In the course of discussion this, I found that they were using a Stew Mac notched straight edge to set their relief. Some context in case you don’t know: The notched straight edge is exactly what it sounds like. It’s a precision-ground ruler with a series of notches cut in its length. The notches correspond with fret positions so it’s possible to very accurately read the fingerboard between the frets.
That’s what this person was doing and (to me) they seemed a little miffed when I suggested that this might not be the best approach. But, isn’t the straight edge a precision tool, made to an accuracy of +/- .0015" per foot? Isn’t it a the perfect tool for setting up a guitar?
Well, yes. But also no. At least, not necessarily in the way it’s more typically used.
Should you use a notched straight edge for setup?
More context, I feel… The notched straight edges are fantastic tools. I have a few and they’re incredibly helpful for diagnosing problems and for setting a neck up for fret work. This latter is probably my most frequent use for the tool. When performing a frets level, I can use the notched straight edge to make sure the fretboard itself is perfectly straight. Then, I know that, when I level the fret tops, they will correspond nicely with the wood of the fingerboard’s surface. That job alone makes the notched straight edge indispensable for me (and many others).
But that job also serves as an example of why it might not be suited to ‘standard’ setup work for most people. In the fretwork I described, I read and set the fingerboard first and then level the frets. Afterwards, I know they correspond. However, there’s no guarantee they corresponded before I did this. In fact, there’s a good chance they didn’t.
Imagine, for example, a neck that wasn’t adjusted perfectly straight before someone levelled it. If a neck had a slight bow when it was levelled, that bow remains in the fingerboard while the levelling process makes the tops of all the frets straight (in relation to each other). In reality, the frets in the middle of the board will actually be taller and those at each end a little shorter, even though their tops are all nice and even.
From a playing setup point of view, that neck can be considered perfectly straight as the strings just care about the fret tops and don’t care a jot about what the board underneath is doing. If you come back later and set up the neck so the fingerboard is perfectly straight you’ll actually cause a back-bow in the plane along the fret tops. The fingerboard is straight now but the fret tops no longer are.
This is the reason I suggested to that emailer, that setting up by reading the fingerboard might not be the best way to proceed. If you’re sure the fret tops correspond perfectly to the surface of the fingerboard, great. If you’re not sure (and usually you can’t be certain), a ‘playing’ setup is probably best done by using the fret tops as your reference.
And, handily, if you’ve got a notched straight edge, this is pretty easy to do. Just shift it slightly up and over so it sits on the fret tops. Two measurements for the price of one. Personally, I prefer a regular straight edge (or even one of the strings) for this job but it’s perfectly fine to use the notched one.
This article written by Gerry Hayes and first published at hazeguitars.com
