PRS SE custom 22 - deformed nut groove : continued

[FBerg]

Continued from the following post:

PRS SE custom 22 - deformed nut groove

I bought a PRS SE custom 22 about a year ago. Didn't play much since it kept horrible tuning. Recently i've decided to deal with the problem by replacing the nut with TUSQ XL. After the removal I've noticed that the profile of the nut's groove is not exactly right-angled (see the attached...

forums.prsguitars.com

In addition to the strange nut grooves which are seen in the post above, a few days ago I also noticed that the edge of the fretboard is not straight! This curve essentially gives a longer fretboard length on the G and D strings (or shorter on the low and high strings - I haven't actually measured). Now I really don't know what to do. i'm afraid that If i'll completely straighten the edge of the fretboard the intonation will be ruined. I'll appreciate any advice.

 

[Tedder]

What model is your guitar? I believe most of the SE's come in a 25" scale. This should be confirmed for your model just to be sure.


Assuming it is a 25" scale, the edge of the nut would be marked at 0 inches, the 12th fret would be marked at 12.5" (exactly half of the 25" scale) and the saddles would be roughly around the 25" scale, although the saddles won't be spot on as this is where adjustments are made for intonation.

Meaning, you should measure from the middle of the 12th fret to the edge of the nut slot on the edges and in the middle to see where the slot is closest to the 12.5" mark.

This will tell you if you can remove material or not. If the longest measurement (being the middle of the slot) is spot on 12.5", then you won't want to correct the slot.

Keep in mind that there could be some level of compensation with the saddles, depending on where they are set on the bridge, that might be useful, but first understand where the 12.5" mark lands from the middle of the 12th fret to that nut slot.

Hopefully this helps!

 

[FBerg]

Measuring the entire scale length from the 12th fret is very difficult since the discrepancy is less than 1 mm. And I don't think the full scale length is actually the problem here. I am more worried that the distance between the nut and the first fret will be off. As far as I understand the distance between frets is crucial, and not something which can be corrected using the saddles.In other words, sanding down the upper end of the fretboard and making it completely flat will reduce the distance between the nut and the 1st fret, while all the other frets will still have the correct ratio.

 

[Tedder]

All of the frets are cut with CNC and will be at the correct distance from each other already. By measuring from the 12th fret back to the nut, you can verify where the nut should be located. That mark will be the correct position for the 1st fret to be spot on.

It might be best for you to take it to a local repair shop and have them look at it just to be sure. They will be able to use the method above to determine if the fret slot can be cleaned up by removing material to straighten it out, or if the nut needs to be carefully glued in at the right spot and the gaps at edges filled in with sawdust and glue, or some other material to match the fingerboard.

 

[Alnus Rubra]

That’s a Friday afternoon guitar if ever so saw one.

If you’re the original owner PRS Customer Service may be able to help. (Ok edit, I see that’s not possible). Wouldn’t hurt to contact them anyway, just to see if they can help.

If you have the necessary skill level, you may be able to rectify this, but part of me thinks why should you have to.

 

[FBerg]

That’s a Friday afternoon guitar if ever so saw one.

If you’re the original owner PRS Customer Service may be able to help. (Ok edit, I see that’s not possible). Wouldn’t hurt to contact them anyway, just to see if they can help.

If you have the necessary skill level, you may be able to rectify this, but part of me thinks why should you have to.

Ye, definitely not the quality I expected from PRS. Really disappointed... . Anyway, I don't have PRS Customer Service in my country and I don't think they can help me with a phone call. The only options left are to try to fix it myself, or to find some expert but I don't think its worth the price. I bought the guitar second hand (but in a mint condition).

All of the frets are cut with CNC and will be at the correct distance from each other already. By measuring from the 12th fret back to the nut, you can verify where the nut should be located. That mark will be the correct position for the 1st fret to be spot on.

It might be best for you to take it to a local repair shop and have them look at it just to be sure. They will be able to use the method above to determine if the fret slot can be cleaned up by removing material to straighten it out, or if the nut needs to be carefully glued in at the right spot and the gaps at edges filled in with sawdust and glue, or some other material to match the fingerboard.

An option i'm considering is sanding down to straighten the fretboard near the nut. This will obviously reduce the spacing between the nut and the first fret, but perhaps this can be compensated in the nut. I guess this will entail constructing a new nut from blank which will be flush with the fretboard but cutting the nut slots at a curve which will effectively increase the nut-to-fret spacing to the correct value. Any thoughts?

 

[Tedder]

Let me see if I can state this a different way.


First figure out what scale your guitar is. It's most likely 25" or 635mm. Unless it's a 245 or a 594, I think it will be 25", but make sure!


If it is a 25" scale, the middle of the 12th fret will be located at the 12.5" mark or 317.5mm (half of the 15" scale). You can then measure from the 12th fret back towards the nut 12.5" (317.5mm) to see exactly where the nut should be located. If this measurement lands on the edge of your fingerboard in the middle where it is the furthest from the 12th fret, then any sanding to straighten out the slot will mess up the scale. But a new nut can be glued in (single drop of super glue) and the gaps can be filled if you want to make it look better.

BUT, if the measurement from the 12th fret back to the nut lands on the fingerboard and not on the very edge, you can sand to that mark to help straighten the slot and will still have correct fret spacing from the nut to all of the frets on the fingerboard. PRS and Cort (SE models) cut those slots on a jig so they will be correct relative to each other. You just have to determine where the nut should be to see if there is any room to sand or not.

Does that make more sense?

 

[Tedder]

also, I wouldn't try to compensate on the nut itself. I have a fair amount of experience building guitar kits and repairing friends guitars. I wouldn't want to do this myself.

The other option would be to sand the edge of the FB flat and then add shims to get the nut location correct. But even that will be a pain in the rear-end since you'd have to shape the shims to the fingerboard radius (10" radius) after gluing them in, as well as the needed thickness to relocate the nut. Lots of room to scratch surfaces on the guitar by accident.

 

[FBerg]

Let me see if I can state this a different way.


First figure out what scale your guitar is. It's most likely 25" or 635mm. Unless it's a 245 or a 594, I think it will be 25", but make sure!


If it is a 25" scale, the middle of the 12th fret will be located at the 12.5" mark or 317.5mm (half of the 15" scale). You can then measure from the 12th fret back towards the nut 12.5" (317.5mm) to see exactly where the nut should be located. If this measurement lands on the edge of your fingerboard in the middle where it is the furthest from the 12th fret, then any sanding to straighten out the slot will mess up the scale. But a new nut can be glued in (single drop of super glue) and the gaps can be filled if you want to make it look better.

BUT, if the measurement from the 12th fret back to the nut lands on the fingerboard and not on the very edge, you can sand to that mark to help straighten the slot and will still have correct fret spacing from the nut to all of the frets on the fingerboard. PRS and Cort (SE models) cut those slots on a jig so they will be correct relative to each other. You just have to determine where the nut should be to see if there is any room to sand or not.

Does that make more sense?

If my measurement is accurate (its difficult to make such measurement with a tape-meter) my scale length is shorter than its supposed to be. From the middle point of the fingerboard edge to the middle of the 12th fret its 12.46" (316.5 mm). This is somewhat consistent with the measurement I made for the nut to 1st fret spacing - 1.385" (35.2 mm), but from what I saw online it should be 1.403" (35.636mm). I made this measurement using a caliper so its more reliable. In any case, it looks like sanding it flat will reduce the scale even more...

 

[Tedder]

If my measurement is accurate (its difficult to make such measurement with a tape-meter) my scale length is shorter than its supposed to be. From the middle point of the fingerboard edge to the middle of the 12th fret its 12.46" (316.5 mm). This is somewhat consistent with the measurement I made for the nut to 1st fret spacing - 1.385" (35.2 mm), but from what I saw online it should be 1.403" (35.636mm). I made this measurement using a caliper so its more reliable. In any case, it looks like sanding it flat will reduce the scale even more...

Based on that, I don't think I would chance sanding it any. Put a new nut on it and either live the the little gaps or fill then in. If that nut is off, the whole guitar is off.

 

[FBerg]

Based on that, I don't think I would chance sanding it any. Put a new nut on it and either live the the little gaps or fill then in. If that nut is off, the whole guitar is off.

Not sure My OCD will allow me to leave the gaps alone, so I'll definitely try to fill them somehow..

 

[deathworlder]

I'd build it up with a colored epoxy wood filler and square it up with a nut seating file.

 

[Tedder]

Yeah, the only downside to filling those gaps, be it color matching saw dust and CA glue or epoxy based wood filler, is that you inevitably glue the nut into the slot more than you normally would, which makes future removal more tricky. How often do you need to remove a nut? Hardly at all, but something to be aware of.

 

[deathworlder]

Yeah, the only downside to filling those gaps, be it color matching saw dust and CA glue or epoxy based wood filler, is that you inevitably glue the nut into the slot more than you normally would, which makes future removal more tricky. How often do you need to remove a nut? Hardly at all, but something to be aware of.

Can you elaborate...?
Are you gluing the face of your nuts or something?

 

[Tedder]

Generally, luthiers will add a small dab of CA glue (super glue) to the bottom of the nut to hold it in place when the strings are removed. It only takes a little encouragement to get it to pop off for replacement. Once you add some glue or epoxy between the nut and the fingerboard, it will just make it more tricky to remove. If the person trying to remove it doesn't know about the filler, they may damage something while trying to remove it. Not a big deal, just something to be aware of.

 

[deathworlder]

Generally, luthiers will add a small dab of CA glue (super glue) to the bottom of the nut to hold it in place when the strings are removed. It only takes a little encouragement to get it to pop off for replacement. Once you add some glue or epoxy between the nut and the fingerboard, it will just make it more tricky to remove. If the person trying to remove it doesn't know about the filler, they may damage something while trying to remove it. Not a big deal, just something to be aware of.

I don't understand how glue on the nut seat has any effect. Seepage to the nut face?
I'm a wood glue kind of guy...

 

[Tedder]

It's just about keep the nut in the correct place while the strings are all off of the guitar.

Got to 5:18 on this video. Here they are using wood glue, so I guess that's OK. I went to a school to learn how to build guitars many years ago, and they were using a single drop of CA glue in the very middle to accomplish the same thing.

 

[FBerg]

also, I wouldn't try to compensate on the nut itself. I have a fair amount of experience building guitar kits and repairing friends guitars. I wouldn't want to do this myself.

Out of curiosity. Why compensating the nut itself is a bad idea? To me (a complete novice) it seems like the easiest solution. Adding wood fillers, shims or veneers, seems much more difficult...

 

[aphantomvaper]

I can add from experience..."gluing" the nut in is bad for future maintenance. Doing this will pull fret board material off with the nut if its ever removed. I mean like permanently gluing it in.

A slight drop of Elmers or Superglue is all that's needed and allows the nut to be popped off for work with no damage.

Also do not use Gorilla super glue!! That stuff expands and really throws off the nut when curing and a devil to remove and clean. I have a SE PG with some slight gaps at the corners of the fretboard where the nut sits because of it. The middle is flat and straight so I try not to look at it too much now or I feel sad.

Good luck, man!!

 

[FBerg]

I can add from experience..."gluing" the nut in is bad for future maintenance. Doing this will pull fret board material off with the nut if its ever removed. I mean like permanently gluing it in.

A slight drop of Elmers or Superglue is all that's needed and allows the nut to be popped off for work with no damage.

Also do not use Gorilla super glue!! That stuff expands and really throws off the nut when curing and a devil to remove and clean. I have a SE PG with some slight gaps at the corners of the fretboard where the nut sits because of it. The middle is flat and straight so I try not to look at it too much now or I feel sad.

Good luck, man!!

Its slightly encouraging to hear that i'm not the only one