Is It Possible to "Fill In" a Nut Slot to Start Over? UPDATE: Shaping the Nut Slot...

[Pete Andreev]

To make a long story short, I'm installing a new bone nut and I took a little too long trying to get the nut slot nice and flat. I couldn't get both sides of the nut to lay nicely in the slot and ended up filing too much. Now the nut slot is too deep...and still not flat.

It wouldn't be as much of a problem if I was using a nut blank but I got a pre-shaped Gibson nut from StewMac.

Is there a way for me to somehow fill in the nut slot so that I can start over??

UPDATE

The CA glue + baking soda worked like a charm...really, really great tip. Now I just need to make sure I don't file it too deep again, but I'm having trouble.

Any tips for squaring the nut slot up and getting it perfectly flat? I'm filing with a mill file and checking the fit very often...but I just can't get the ends of the nut to fit perfectly in the slot.

[Ned Knepp]

How much fill are we talking about, Pete?

BTW, I don't know what you are calling "flat" but you probably don't want it to be flat from fingerboard to head. It's usually better if the slot dips toward the tuners so you have a solid "stop" point at the face of the nut. Of course you don't want to have a knife edge there but you do want the vibration to stop there. 

[Paul Verticchio]

Hi Ned.

Just a note: Depending on the design of the guitar, the nut may not slope toward the tuners like a Martin style nut. MOST Gibson (and Gibson style instruments) slots are flat in both planes. Fender style nuts are yet a completely different story

Summary: match the geometry of the existing slot.  Do not modify it.

Have a good one, buddy :)

[Ned Knepp]

Thanks Paul. Every so often I get my ignorance out and wave it around a bit. 

[Paul Verticchio]

If you learned that (I call 'em brain farts) from anyone; you learned it from me :)

Take care, my friend :)

[Glen H]

Pete, are you talking about the slot in the neck that the nut sits in or a string slot in the nut?

[Mike Kolb]

Luthiers Mercantile (lmii.com) sells a bone nut shim that will give you an additional .020".  They're 3.25"L, .475"W and .020" thick and they only cost about $3 or less.   

Another use for them is to "fill & start-over" on a single string slot that was cut too deeply, (if it's a .020" slot or less).  A lot of folks use bone dust with cyanoacrylate, but it's just as easy (and more solid) to file the slot out to .020" and insert a little piece of leftover bone shim with cyano, trim to fit and begin again.  If it's a wider slot, use 2 pieces. 

[Russell Vance]

Nice call Mike,

I usually use a sliver of Mahogany washed and stuck with cyanoacrylate under the nut to jack it up a few thou'  but I can see what you say as being a really good alternative.  Nice.

Also, as Paul laments next post, all of us have stuffed up numerous nuts in our time....some of us have even made some really well executed  left hand ones.  Hmmmmm.

Rusty.

[Paul Verticchio]

Hi Pete.

To add a bit of encouragement, the minor issue you're discussing have happened to ALL of us once (or several times) over the decades.

Also, the nut you got from S-M will not be a "100% compatible drop-in". The nut slots will likely have to be adjusted for the best playing action at the first fret.

Don't worry. These experts will be able to walk you right through the "rescue".

Best of luck

[John]

Baking soda and CA glue. IMHO is works better than anything else.

[Hesh Breakstone]

Even though we now know the OP means the channel that the nut is installed in I would match your CA glue and baking soda and raise you UV cured dental fillings.

We fill not slots (string slots...) with UV cured dental filling also available in matching shades of white, brown, and maybe even green....;)  Seriously some years back we enlisted the assistance of a dentist and he showed us how to use a UV light and actual dental fillings.

It's as hard as teeth and certainly way harder than baking soda and CA which never lasted very long in my experience.

The process is the same as going to the dentist sands the numbing, nuts don't seem to feel pain...  Clean the slot, perhaps file a bit of a dovetail in the bottom, acid etch, fill with bonding agent, let cure for 20 seconds with UV light, fill with your choice of 30 colors..., let cure for 40 seconds with the UV light.

What resutls still cuts with our nut files but is harder than most materials including bone at times depending on the source of bone.

One of my clients who has a guitar that I built needed an emergency repair before a big gig and we had no time to make a new nut.  Filled the slot with dental fillings, that was three years ago and counting... and it's still good to go.

[Jon Hiltbrand]

Hey Pete,

How about a pic? Sounds to me like you mean the "shelf" that the nut sits on, not the string slots.  Is that right?  If so, I would be very careful about removing too much material.  What is the guitar?  As Paul pointed out, not all are meant to be flat (aka martin style).  Too late this time, but I find a small chisel is much more effective at truing up a shelf than a file. Just make sure to work from the ends toward the middle so you don't chip the finish or wood at the ends.

Another thought it to check the nut.  Is it flat and square (or angled appropriately to the slot)?

Jon

[Pete Andreev]

Hi all,

To clarify, I'm talking about the nut slot, not a string slot. I definitely understand what you guys are saying about tilting the nut back away from the fingerboard, but I'd rather go for a straight shelf to seat the nut on and make the string slots achieve the necessary contact point.

I'd rather not buy a new nut blank...I have a perfectly good vintage bone nut ready to go here. I also don't like the idea of a shim...I'd have to shape it perfectly to sit in the slot which is what caused this problem in the first place.

I like the idea of making some sort of filling material with super glue and something else...any additional suggestions besides baking soda and CA glue?