Filed my nut slot too low.. :(

HodgdonExtreme · #1 07-06-2020, 08:48 PM

Bought a new D28 in December. LOVE it.

But when I set it up, I went a shade too deep on my G string. I filled with baking soda and superglue, and had another go of it. The Stew Mac hiroshima file I was using just doesn't cut the new material right. Went too deep again. Refilled. Refiled. Managed to get the correct depth this time.

But I can't get the string to slip thru that nut slot without any bind, so that string "pings" and it's really tough to get it tuned just so. Plus bending on that string causes the string to go out of tune. If I bend the string between the tuning machine and the nut, it pings. If I then give the string a good bend between saddle and nut - it pings again. Ugh.

I've tried very gently filing the bottom of the slot to ensure it's smooth. I've tried "polishing" the nut slot with a spare G string by rubbing it back and forth. I've tried a bit of graphite lube. I have the relief angle of the nut slot a bit steeper than the string angle on it's way to the tuning machine - so that the string is only touching a "shelf" on the nut about 1/16" long.

Frustrated with the hysteresis in the tuned pitch of that string (I've been tolerating it for months, now), tonight I had another go of it - and while I solved the hysteresis problem - the slot is now too deep... Again... Which is to say that with relief at about .007", action feels great up and down the neck, a *smidge* of tolerable (to me) buzz on the low E if I strum hard, the G string has a good buzz and overall metallic "zing" to it. I did try increasing relief to remove the G string buzz but by the time I was satisfied, the action had very noticeably deteriorated (didn't measure, but it moved a fair bit)

Is it time for a new nut?

I'm a handy guy, but I'm (obviously) not a luthier. Is fitting a new nut within my wheelhouse? I've read a little about it and watched some YouTubes - removing old nut without damaging the headstock at all is intimidating, and getting a really sweet fit to the neck/peghead seems kinda tough. To achieve the original fit-up, it seems like the nut, neck and peghead would need to be final-sanded as one assembly, which is obviously impossible once the guitar has been finished. It's a beautiful guitar and I don't want the new nut to look all DIY!

Is there another repair I could/should attempt before resorting to a new nut?

lar · #2 07-06-2020, 10:58 PM

You sound frustrated - sorry to hear that. If you want more frustration then I recommend you try making a nut from scratch. I just made my first one: it was time consuming and frustrating. However, I was happy I didn't make any mistakes, so I didn't have to start over. And it turned out very well - probably better than what a repair tech would do. But I could very well have put hours into a nut only to screw it up and have to start over. It happens.

However, I learned a bunch, and that's what I was after - the knowledge.

Unless you really want 'the experience' (like I did) I'd take it to a luthier/repair tech. They can do in 40 minutes what would take you 8 hours (especially considering the research you would need to do before even starting).

If you decide to try it: the side of the nut might have been sprayed with finish after installation and you'll need to take a blade and score the sides of the nut to break that bond. Then, if you have any trouble getting it out after that: STOP IMMEDIATELY, AND TAKE IT TO A REPAIR SHOP. You don't want to tear out the wood trying to get the nut out.

As final advice, I will tell you what a very wise person told me. Never do something to an expensive guitar that you've never done before. In fact, I'm considering buying a 'beater' guitar just for this purpose (to practice minor surgeries). It's cheap insurance. I would hate for you to damage your new guitar.

If you do decide to DIY, let me know and I'll give you some references that I used (web sites, etc). And after your done, let all of us know how it went.

Neil K Walk · #3 07-06-2020, 11:37 PM

Fill the slot with CA glue and do it over.

keith.rogers · #4 07-07-2020, 05:20 AM

https://youtu.be/slCMkvEfK_U

EZYPIKINS · #5 07-07-2020, 05:56 AM

I have used this trick in a pinch. It does work. Myself though, after filing a bone nut too low. I got a replacement bone nut. Filed off some shavings and used that instead of baking soda. Just make sure you mask off your headstock and fret board. Follow video you'll be fine. Have one guitar that has this repair for over a year and still going strong.

JonWint · #6 07-07-2020, 06:37 AM

File the slot wider, not deeper to eliminate ping.

redir · #7 07-07-2020, 08:07 AM

You can just shim it and recut the slots too. It's not at all uncommon to blow the nut so to speak. It happens to me once in a while even after 25 years experience. Of course to get a nut right you are one file stroke from blowing it so it is very sensitive work.

oldduc · #8 07-07-2020, 08:15 AM

When I cut a nut too deep, I've been using a product named "Bondic" to fill it and recut it. It is a UV hardened resin. It only takes a few seconds and is not messy like CA + powders. Dan Erlewine uses a similar product now. Anyway, you can get Bondic from the manufacturer or from Amazon or other online sellers

Neil K Walk · #9 07-07-2020, 08:36 AM

Quote:

Originally Posted by keith.rogers

https://youtu.be/slCMkvEfK_U

There you go. Hadn't heard of using baking soda but there's more than one way to skin a cat to get nylon strings.

HodgdonExtreme · #10 07-07-2020, 08:43 AM

Quote:

Originally Posted by JonWint

File the slot wider, not deeper to eliminate ping.

So, the G strings I use are .025" or .026" and the set of nut slot files I've got include a .024" and a .032". I'm already using the .032". Should I move up to the .036" file? Won't hurt anything have the slot overly wide like that?

Quote:

Originally Posted by oldduc

I've been using a product named "Bondic" to fill it and recut it. It is a UV hardened resin. It only takes a few seconds and is not messy like CA + powders. Dan Erlewine uses a similar product now. Anyway, you can get Bondic from the manufacturer or from Amazon or other online sellers

Forgot about this stuff. Heard about it a while back and was meaning to buy some to try out for various odds and ends. Definitely worth a try before replacing nut!

How does it file with your nut slot files? I ask, because the Soda/CA "material" I created just doesn't file away "right" like Tusq or bone. Hard to explain, but it's really grabby on the file and almost "chunks off" instead of filing away into dust.

YamahaGuy · #11 07-07-2020, 09:11 AM

If you're comfortable to file, you should be able to handle installing a new nut. All the ones I've changed, knock on wood, and never damaged the headstock. I take the blunt end of my large Swiss Army knife, rest the plastic rounded end on the face of the nut, slightly angle the knife up off the fretboard, and give a tap. The rosewood or ebony fretboard does not get marred. Sometimes it takes a harder tap than others. What I find hardest to do installing the new nut is getting the fit right between the fretboard and the headstock overlay. The most recent one I did was perfect and I didn't even have to glue it. Good luck.

JonWint · #12 07-07-2020, 10:52 AM

Quote:

Originally Posted by HodgdonExtreme

So, the G strings I use are .025" or .026" and the set of nut slot files I've got include a .024" and a .032". I'm already using the .032". Should I move up to the .036" file? Won't hurt anything have the slot overly wide like that?

A "U" shaped slot wider than the string will still locate it properly side to side. The other place the string can hang up is where it first touches the nut (headstock side). Make sure the slot bottom falls away from the fretboard side of the nut so the windings don't catch on a sharp edge.

When slotting nuts, I keep a set of old strings to pull through the slots to check for width and resistance to movement.

HodgdonExtreme · #13 07-07-2020, 11:10 AM

This is the basic geometry I've created in my filing efforts. The blue represents the string, and the red is the shape/angularity of the slot:

I try to create a flat shelf about 1/16" long for the string to rest on, and then the bottom of the slot falls away - at a steeper angle than the string will have when it goes towards the tuning machine.

Idea being the string will only set on the flat "shelf".

Am I doing it wrong? It's worked great on all the other guitars I've done this to. The difference here is the baking soda and superglue material files weird and seems to be "grabby" on the string.

I also keep old wound strings in my nut-file set, so that I can drag them thru the nut slots to polish/smooth them out after I'm done with the file.

Big Band Guitar · #14 07-07-2020, 12:12 PM

Many years ago I saw a article in frets mag. on making a nut slot cutter that would guide and cut nut slots to a exact depth. Later widening the slot to fit the string would be done with a file.

It was a aluminum block with a slot that held a hacksaw blade reground to a knife edge. The block rode on the frets and the blade cut to the depth set and no farther.

I gave the article to a machinist friend who made one for me.

I use gas orifice broches to widen the slots.

I would post a picture but can't.

charles Tauber · #15 07-07-2020, 08:02 PM

Quote:

Originally Posted by HodgdonExtreme

I try to create a flat shelf about 1/16" long for the string to rest on, and then the bottom of the slot falls away - at a steeper angle than the string will have when it goes towards the tuning machine.

Idea being the string will only set on the flat "shelf".

The intonation is compromised if the string length is not defined by the fingerboard face of the nut. You can also get a non-clear sound if the string breaks embedded in the thickness of the nut.

If you have a flat shelf, there is the potential that any slope towards the fingerboard will result in the string not breaking over the nut at the fingerboard face of the nut. For that reason, I slope the nut slot from the face of the nut (against the fingerboard) so that the string is certain to break over the nut at the face of the nut. The angle of the slot is such that the string contacts the slot for at least part of the thickness of the nut so that the string does not bear solely on a (weak) knife-edge at the face of the nut.

Not all CA glues are created equal. Depending on the brand you are using, you might try a different brand. I've not had any issues with the baking soda (or bone dust) and CA glue method.