What does “middle of 12th fret mean” when calculating scale length?

[Daddy Hojo]

I built a t-style guitar a few years back and it seems I’ve set the bridge too close to the neck. My intonation is always reading a bit sharp and I have the saddles set way back. I’m going to pull the bridge and fill the holes.

I’ve always heard “measure from the nut to the middle of the 12th fret” as the midpoint for your scale length. I thought I’ve been doing this correctly all these years, but I’m starting to wonder if I misunderstood what the “middle of the 12th fret” means. Does this mean the middle of the actual metal fret? Or does it mean the middle of the fret “space” (which would be between the 12th and 13th fret)- about where the fret markers are?

I feel dumb if I’ve been doing this wrong all along, but this is something that - because fret can mean “lil metal thing” as well as a “unit of fretboard space” - is very hard to google and get a straight answer.

Help?!

 

[chris m.]

Middle of the actual metal fret.

 

[Jupiter]

it means the top of the crown, as opposed to the leading or trailing edges of the fret

 

[TeleTucson]

It is the middle of the actual metal fret. This is where the string is clamped when you put your finger on the space on the headstock side of the 12th fret. It should be half the length of the string measured from the "guitar side" of the nut to the saddle, and the saddle adjusted to tweak it just right to account for minor effects from string diameter, etc.

 

[etype]

Middle of the actual fret.

Edit: Haha, during the 10 seconds it took me to write these 5 words, three people beat me to it!

 

[Daddy Hojo]

it means the top of the crown, as opposed to the leading or trailing edges of the fret

It is the middle of the actual metal fret. This is where the string is clamped when you put your finger on the space on the headstock side of the 12th fret. It should be half the length of the string measured from the "guitar side" of the nut to the saddle, and the saddle adjusted to tweak it just right to account for minor effects from string diameter, etc.

I thought so, but I saw a YouTube video that made me doubt this. Thanks for setting the record straight guys!

 

[Daddy Hojo]

I also saw the guy on the YouTube video using an electric drill to put in neck screws and thought, “do I trust this guy’s opinion?”

 

[TRexF16]

I got into a very undesired but, in my opinion, necessary, confrontation over on the Peavey guitars forum a few years ago because a guy was trying to sell a Peavey neck (that was a 25.5" scale) as a 24.75" scale. The guitar in question featured both scale lengths over the course of its history and the 24.75 was by far the rarer of the two. I felt it my duty to make sure potential buyers knew what was actually being offered for sale. The seller was measuring his half length at a point midway between the 11th and 12th frets and was convinced this was the right way to measure scale length. Once I pointed out the mistake he even posted a picture to "prove" he was right that showed the center of the 12th fret dead on at 12.75".
I finally just gave up.

Short version - what all those other guys said is right
Rex

 

[trev333]

if you need an idea of a new placement point, here's where my bridge sits on a body that wasn't pre drilled... I used where I wanted my saddles to sit, to be the place.... after measuring the true scale lengths on a few other teles...

as measured from the middle of the 12th fret wire....

 

[radiocaster]

To be fair it doesn't matter so much which part of the fret because you're going to have to dial a couple of mm back for correct intonation anyway. Middle of fret/middle of saddle is just a starting point.

Also, it's not middle of nut, but end of the nut, fingerboard side.

 

[EsquireOK]

It means the line at which the fret slot was cut. I.e. don't measure to one of the edges of the fret. Measure to the fret's center (now that there is a fret there, instead of a line where a slot will be cut).

 

[RogerC]

Also, it's not middle of nut, but end of the nut, fingerboard side.

This is an important distinction as well. Be sure you’re measuring from the fretboard side of the nut.

 

[bettyseldest]

Its is the length over which the string vibrates. At one end you have your nut and at the other the fret. The nut will have an angled slot such that the fingerboard edge is highest. This is the contact point. The highest point (usually the middle) of the fret is the other contact point. So distance between the two will be 12.75" on a standard Fender Tele or Strat scale neck.

 

[Old Deaf Roadie]

Stew-Mac has a free online fret calculator on their web page somewhere. You enter your scale & it tells you where to place the frets.

 

[Freeman Keller]

There is a very good article in the latest issue of American Lutherie about this exact subject. Yes you do measure to the center of the crown but it is also important to know where the saw kerf was on the nut - if the center line of the saw was at the exact zero fret location then the nut will be shifted towards the bridge by half the width (about 0.011). It is interesting that some builders do this intentionally - maybe even shift the nut a little more towards the bridge to help tame inharmoniously. You also, of course, need to assume (or measure) that the frets were cut and installed at exactly the location predicted by rule of 18 or 12th root of 2 or whatever you decide to use.


(link removed) Measuring Scale Length of Fretted Instruments
by R.M.Mottola
What’s the scale length? Isn’t it just twice the distance from the nut to the 12th fret? Yeah, kinda, but there can be a lot of complicating factors when working on old instruments. Like maybe the nut position was compensated, or just cut wrong. Or maybe the 12th fret was a little off. The fret positions might have been calculated using the old rule of 18. Here’s how to find out what’s really going on.

 

[DesmoDog]

I built a t-style guitar a few years back and it seems I’ve set the bridge too close to the neck. My intonation is always reading a bit sharp and I have the saddles set way back. I’m going to pull the bridge and fill the holes.

I’ve always heard “measure from the nut to the middle of the 12th fret” as the midpoint for your scale length. I thought I’ve been doing this correctly all these years, but I’m starting to wonder if I misunderstood what the “middle of the 12th fret” means. Does this mean the middle of the actual metal fret? Or does it mean the middle of the fret “space” (which would be between the 12th and 13th fret)- about where the fret markers are?

I feel dumb if I’ve been doing this wrong all along, but this is something that - because fret can mean “lil metal thing” as well as a “unit of fretboard space” - is very hard to google and get a straight answer.

Help?!

A couple comments, all in my humble opinion of course;

I measure the bridge position from the nut, not the 12th fret. The nut is the datum, everything is measured from there so you don't keep compounding errors. Measuring the bridge position from the 12th fret means you're adding the error of the 12 fret position to the error in the bridge saddle position. Having said that... chances are the error at the saddles because you measured from the 12th fret isn't what your problem will be, so that's a problem in principle more than practice. It certainly holds true for positioning frets though. Measure from the edge of the nut, not the previous fret.

Calculations based on "scale length" give precise positons for the frets that people accept as accurate. The bridge position based entirely on scale length, not so accurate. Everyone tries to get the frets as close as possible to the calculated positions. When it comes to saddle position, most everyone says it should be whatever your scale length is, plus some fudge factor. And then they use adjustable saddles so the guitar can be dialed in to where it really needs to be.

So, to address your post - the scale length IS twice the distance from the nut to the middle of the 12th fret. BUT... the saddles of the bridge are NOT at twice the distance of the nut to the 12th fret. They are at some distance more than that because of the characteristics of the string itself, which play a part in the physics but not the simplified calculations.

It's been a long time since I've built anything (c'mon build challenge! Inspire me!) so I don't remember the details but I'm pretty sure all the guitar building books I've seen talk about this.

And for what it's worth, I have never thought of the space between the wire as "frets". I would argue the term can't mean that. But I'm the kind that cringes at stuff like when someone refers to an engine as a motor so I may not be the best judge of these things.

 

[Jupiter]

A couple comments, all in my humble opinion of course;

I measure the bridge position from the nut, not the 12th fret. The nut is the datum, everything is measured from there so you don't keep compounding errors. Measuring the bridge position from the 12th fret means you're adding the error of the 12 fret position to the error in the bridge saddle position. Having said that... chances are the error at the saddles because you measured from the 12th fret isn't what your problem will be, so that's a problem in principle more than practice. It certainly holds true for positioning frets though. Measure from the edge of the nut, not the previous fret.

You need a LOOONG ruler for that!

 

[trev333]

I use this ruler to measure from the inside of the nut to saddles.... cheap enough to buy...

 

[boop]

I think its totally fine to measure from the 12th fret especially if you are using intonatable (intonatable?) saddles. You intonate based on the 12th fret, so why wouldn't ya want the distance from nut to 12 to saddle to be the same?

Even if the 12th fret is incorrectly placed; that fraction of a mm of an error (or you're screwed anyway) can be corrected for by the movement of the saddles.

 

[beagle]

I also saw the guy on the YouTube video using an electric drill to put in neck screws and thought, “do I trust this guy’s opinion?”

Yeah, he should be using air tools like they do in the factories.