Fender vintage - truss rod adjustment

Ah yes, the truss rod...

When I was but a young lad, dreaming sleep away with erotic dreams of sinuous, curved Fenders and dark, sweet Gibsons which shamed my clunky third rate guitars, a truss rod was just the thing that made your guitar neck straight. Buying a secondhand guitar always involved sighting down the neck, as if you knew what you were doing, and could spot a maladjusted truss rod at a glance. This at least was simple; a good guitar had a straight neck and a bad guitar didn't.

Well, surprise, surprise - turns out it’s not that simple at all. A guitar string is fixed at both ends and vibrates up and down in the middle when plucked, so it makes sense that a guitar neck should be bowed slightly in the middle to make room for the vibrations. Rather than being the big stiff rod that makes sure the neck is always kept to the straight and narrow, the truss rod turns out to be a tool of skill and subtlety, whose minute variations and delicate adjustments can tune the neck to exquisite refinement.

Unless you go vintage.

More grief than relief.

My vintage strat style neck should apparently have a relief measurement of 0.12in - it's probably different for your guitar. Now, a little bit of background here: The neck I was attempting to match with the James Bisset Fiftieth Anniversary strat was my old and faithful Squier Japanese Hank Marvin Strat neck, a one piece maple neck. But for reasons I still can't quite fathom, I decided at the last minute to get a rosewood fingerboard. On many guitars, the truss rod adjustment is made by accessing the truss rod nut in the headstock and in others, by tweaking a nut at the other end, where the neck meets the body.

And that's certainly true of the strat maple fingerboard and my Vox Tornado above. But the same can't be said of the Strat maple neck and rosewood board. Guess where the adjustment lies there?

That's right, on the end of the neck and accessible only when you take the neck right off.

So, a few careful tweaks that should take half an hour, end up with this particular neck taking days. I may be wrong here, but my reckoning is that if you take the strings off, take the neck off, adjust the truss rod, put the neck back on, put the strings back on and bring the neck up to tension, then you'd better wait at least 24 hours and let everything settle in before you take any more measurements. What on earth was Leo Fender thinking of?

And how does it measure up?

The technique for measuring your neck relief before adjusting the truss rod involves the use of a 'feeler' or thickness gauge. Now I'd never heard of these before, so for those of you as ill-educated as me, here's a picture of mine:

Each one of these strips is a different thickness, so by fitting a capo at the first fret, holding down the sixth string at the last fret and then slipping the various thicknesses between sixth string and fret around the eight fret, you can measure the gap.

If you're quick, you'll spot the logical flaw here. The thickness gauge will indicate what the gap is not rather than what the gap is: e.g. the gap is greater than 0.006 and less than 0.008 so it's probably around 0.007.

And just to help you, the string will obligingly move up out of the way if your gauge is thicker than the gap.

Bent as a nine bob note.

So I worked out a better way. I bought a two foot steel rule and cut it down to around eighteen inches so it was the same length as the fingerboard, rested it 'edge on' over the frets and slipped the gauge through the gap as before. Completely different result! At last we're getting somewhere. At least until I double checked, turned the ruler over to use the opposite edge and couldn't get the gauge through the gap at all. It would appear that a stainless steel rule is not the same thing as a 'straight-edge', which I'm now guessing is a technical term.

Turn and turn and turn again.

Back to the string as straight-edge then. I started the process with the truss rod nut set as you see it above, with the slots vertical and horizontal.

The gap measured between 0.006 and 0.007in.

So I turned the nut 45° anticlockwise, and 24 hours later the gap was between 0.008 and 0.009in.

Another 45° and 24 hours and the gap was greater than 0.12 and less than 0.15in.

I turned the nut back approx 15° clockwise tonight. I'll report back tomorrow on the results.