JM Jaguar intonation issues

[hwestman]

Could be too much neck relief which can make notes go sharp.

[akpasta]

I turned the truss rod screw about 1/4" tighter and it cleared up the notes going sharp from the third to 5th frets. BUT, it did not rectify notes going sharp on the first fret. Pretty much all of them go sharp on the first fret. So that's got to be the nut.

Does that mean a shop will file down the slots or take the nut off and file down the whole bottom of the nut?

Thanks,

[timtam]

A tech will file down the nut slots, without taking the nut off. Filing underneath is not usually done except maybe as a starting point to get lots of material off a very high nut, before going slot by slot. Or for someone who doesn't have the expensive nut slot files. But it's much more hit and miss. Slot by slot is the best approach, checking first fret action on each string as you go.

[akpasta]

Alright, so I took the guitar in on Saturday. Again, the G, B, E strings are properly intonated but go sharp when fretted from the 1st through 5th frets or so and then get better as you go up the neck, with correct intonation at the 12th fret.

Sure enough the tech identified that the G, B, and E treble-side strings were too high at the nut. He filed them down as much as possible without going so low that it caused fret buzz. Filing the nut solved the B and E strings going sharp, but the G, he could not go low enough to fix the issue.

Of course fixing the other two strings made things sound REALLY bad when you play any chords, because now it's only one string that's sharp.

This is where things get weird.

He said sometimes certain model year Fender guitars vary on exactly where the nut is placed, sometimes it's a little bit too far back, sometimes too far forward. He said that the problem with this guitar is the nut is slightly too far back. He said in order to get it playing properly I would need a compensated nut, or a small extension placed in front of the G string slot on the nut. I'm waiting to hear exactly what they recommend.

What are your thoughts on all of that?

Here's a photo of a compensated nut by Earvana, you can see how the string slots end in different spots, the G slot being the one that's the longest, as the tech suggests.

[timtam]

He said sometimes certain model year Fender guitars vary on exactly where the nut is placed, sometimes it's a little bit too far back, sometimes too far forward. He said that the problem with this guitar is the nut is slightly too far back. He said in order to get it playing properly I would need a compensated nut, or a small extension placed in front of the G string slot on the nut. I'm waiting to hear exactly what they recommend.

News to me that Fender sometimes got the nut positions wrong. Much more common to have a poorly cut or worn nut with the slot slope from front to back wrong ...
http://www.lutherie.net/nuts.html

But you can mock up an extension to see if it solves your G intonation problem, to see if a compensated nut would be a permanent solution. Maybe with a short strip of aluminium with a slot for the G, and hopefully less severe than this, but same concept ...

[Peckhammer]

He said sometimes certain model year Fender guitars vary on exactly where the nut is placed, sometimes it's a little bit too far back, sometimes too far forward.

On a neck made on a CNC machine? Really?

A nut too far back would affect all strings. So would a nut too far forward — and in your case maybe the 3rd string would be right but all the others would be off. Also, why could he not lower the g-slot further? It would not have to be lower than the b-slot.

A compensated nut might do the trick, though. You could test like someone suggested. A simple test would be to put a capo on between the nut and first fret. Tune the 3rd string (before putting the capo on) using an accurate tuner (peterson strobe, for example). With capo on, check the note at the 12th fret, when fretted. If still an accurate g-note, check the other frets. If they are off, adjust the saddle until one of the errant frets is correct, then see what the other frets are like.

Another method would be Placing something flat in front of the string such as part of a popsicle stick 1/8th” wide or less, and sanded to be as high as the 1st fret. Then place a piece of the smallest string in a wound set parallel to the nut on top of the popsicle stick. The smallest string in a wound set is the 3rd string (g) after you unwrap the wind. Move the string fore and aft, setting intonation, then testing how the notes play up and down the neck.

This technique is based on how you set intonation on an acoustic bridge saddle. Google it for examples, then apply the technique to what appears to be your nut problem.

[akpasta]

Hey folks thanks for chiming in.

Shop called back and said they were wrong and they were able to file down the G-slot enough to bring it in tune without buzzing. I'm going to check it out today.