Revisiting Brian May - intonation and ‘offset’ zero fret

Remember a while back I went off on a ridiculous investigation into Brian May and the zero fret on his famous Red Special? Well, some people do. I’ve gotten a few emails about one particular throwaway comment I made in that email. And, since, it’s interesting and educational, I thought I’d talk a little about it.

I spoke briefly about the guitar having had a specially-made ‘offset’ zero fret installed. I touched briefly on the reason but didn’t explain it fully.

Brian May Red Special Repair Background

Brian is, understandably, protective of his Red Special. However the instrument had gotten to the point where the zero fret was essentially unplayable. All the other frets were well worn too but Brian apparently didn’t want to mess with the mojo too much and confined his fretwork to only the zero fret.

Andy Guyton from Guyton Guitars was the person tasked with the job. Andy carefully (and nervously, I’m sure) replaced the zero fret with a new one. It looked like all was well but there was an unforeseen problem. The intonation was now made much worse.

The new zero fret was throwing things off. Let me illustrate…

Brian May Red Special zero fret replacement and a knock-on problem

The impact of frets on intonation

In an ideal system, we have a perfectly crowned fret that looks like a nice domed, semi-circle from the side. The fretted string contacts, and bears off, one small point slap bang at the top (and in the middle) of this crown. The take-off point is indicated with an arrow in these images.

Ideal fret intonation points

All is well.

As frets wear, however, that crowned dome shape changes and flattens out on top. This shifts the point on which the string bears off. The worn fret’s intonation point is moved a little towards the bridge.

Intonation shifts as fret wear progresses

If fret buzz isn’t a concern or problem, as the wear progresses, it’s quite feasible to reset the guitar’s overall intonation to compensate for this shift in fretting positions.

There is a caveat here that I’ll talk about in a minute but, for now, let’s assume that all is well in camp and the intonation gets set to account for the worn frets.

Then some guy comes along and hammers in a new zero fret.

Replacing zero fret with perfectly crowned fret shifts its intonation point

Oh, no. It’s gone and messed up our weirdly working system. The lovely new zero fret has its contact point back at the centre. This means the gap between the zero fret and the take-off point of the first fret just got longer.

Cue, intonation woes.

What to do? We need the height of a new zero fret because the old one was unplayable but unless we replace all the other frets with nice, properly crowned wire (not an option), we’ve got a mismatch in intonation points.

Andy Guyton’s clever solution?

Get a nice big fret and shape it so that it retains the height but moves the point where the string takes off to match the worn frets.

Fiendish.

Crowning replacement fret to offset point restores the worn intonation points.

The ‘ideal’ solution would obviously be to replace all the frets but that’s not what the owner of this guitar wanted. Andy came up with a nice way to respect those wishes and work around the limitations they imposed.

That’s brilliant. Nice one, Andy. Respect.

By the way, that caveat regarding ‘re’-setting the guitar’s intonation to compensate for worn frets is that its effectiveness really depends on the ‘consistency’ of the fret-wear. If some frets are more worn than others things get tricky and intonation (never an exact process anyway) inevitably has more compromises. Personally, I imagine setting up Brian’s Red Special is a frickin’ nightmare. 😉

I’d still have a go, though.