Questions about Tusq Preslotted Nut Relacement

[JackB1]

OK so I tried my DIY Nut replacement on a Martin guitar with a pre-slotted tusq nut and it wasn EPIC FAIL. I ordered another and need a little advice/help.
So the old nut came off easily. Where I screwed up was in sanding down the new nut. I angled the bottom badly. So here are a few questions:

1-What is best grit for sandpaper for sanding down a tusq nut?
2- how do you keep the bottom square?
3- how much do you sand down off the bottom? Enough to make it match the old nut?
4- I have nut files, so should I file the slots at all or leave them as is? How deep should each string sit in the slot?
5- Can I just install the nut "as is" and then file the slots to proper clearance height or is that a bad idea? Or should I sand down the nut until I have proper clearance height or should I leave it a touch high and then fine tune with nut files?

Thanks!

[Mirosh]

"should I leave it a touch high and then fine tune with nut files?"

Yes, that. I have never installed a new nut, in part because of all the potential mishaps involved, including those you've run into. But mainly because the nuts on my guitars are OK, after some careful tweaking.

Do a search for "nut slot height" to find some helpful discussion by those know the subject well.

[JackB1]

Originally Posted by Mirosh

"should I leave it a touch high and then fine tune with nut files?"

Yes, that. I have never installed a new nut, in part because of all the potential mishaps involved, including those you've run into. But mainly because the nuts on my guitars are OK, after some careful tweaking.

Do a search for "nut slot height" to find some helpful discussion by those know the subject well.

It's definitely one of those things that sounds easy but there are many ways you can mess up.

[YamahaGuy]

The angle across the top, as well as the angle across the front of nuts makes it more difficult to sand the bottom off and keep a nice square edge to the bottom, relative to the back. For that reason, I seldom sand down the bottom. Even if the nut is really high. I almost always deepen the nut slots at the top, and if the slots are so deep the sides are higher than the top of the strings, I'll sand down the top to correct for that. I prefer 80 - 120 grit.

[mercy]

Put the nut in place and draw a line on it. That will be the fret line. File down to, but leave the pencil line. Alternately put another nut or larger piece of wood squeezed against the nut and sand away. The bottom will be absolutely square. Youll have to do a little math for how much to take off. Use 80 grit then before you are done 120 to assure complete contact with the neck. Caution, some guitars require an angled bottom. You can cut a piece of wood that angle and do the above to reduce the height.
Arent the slots in Tusq just flat across the top? If thats so they will need a lot of work to get the slots the right shape. The right shape is rounded down and to the side which it rides and angle back to its post. You want the string supported all the way while its on the nut. Straight angles or tops are not good.

[Robin, Wales]

Have you found that the string spacing is different between your original Martin nut and the Graphtec replacement? Graphtec tend to cut all their nuts with equal spaces between the strings. Martin use equal or proportional centres. The result is that the treble strings are closer together on a pre-cut Tusq nut and the bass strings further apart.

I can play a 1 11/16th Martin nut but struggle with a 1 11/16" pre-cut Tusq nut - despite the overall string spacing being 37mm on both.

[JackB1]

Originally Posted by Robin, Wales

Have you found that the string spacing is different between your original Martin nut and the Graphtec replacement? Graphtec tend to cut all their nuts with equal spaces between the strings. Martin use equal or proportional centres. The result is that the treble strings are closer together on a pre-cut Tusq nut and the bass strings further apart.

I can play a 1 11/16th Martin nut but struggle with a 1 11/16" pre-cut Tusq nut - despite the overall string spacing being 37mm on both.

No the string spacing on the replacement nut was identical to the original Martin nut. So was the width. I just needed to sand down the thickness a tad and then the height needed to come down quite a bit.

[runamuck]

Originally Posted by JackB1

1-What is best grit for sandpaper for sanding down a tusq nut?

It depends on how much you need to remove but I'd usually start with 120 and finish with 600 and then polish it on a buffer.

2- how do you keep the bottom square?

Glue or screw a piece of wood that's been accurately cut so that at least 2 adjacent surfaces are at 90 deg, a little less high than the nut will be when finished to another small piece of wood with 120 grit paper attached. Use the 90 deg piece as a fence to keep the nut at a right angle while sanding.

3- how much do you sand down off the bottom? Enough to make it match the old nut?

Leave it a bit high and reduce the string height with your nut files.

4- I have nut files, so should I file the slots at all or leave them as is? How deep should each string sit in the slot?

It's best that slot are cut no deeper than they need to be to ensure that the strings don't move sideways. Usually a half the depth of the string or a bit more will do that.

5- Can I just install the nut "as is" and then file the slots to proper clearance height or is that a bad idea? Or should I sand down the nut until I have proper clearance height or should I leave it a touch high and then fine tune with nut files?

You can do it various ways, whatever is best for you.

Good luck and just go slowly.

[Robin, Wales]

Originally Posted by JackB1

No the string spacing on the replacement nut was identical to the original Martin nut. So was the width. I just needed to sand down the thickness a tad and then the height needed to come down quite a bit.

You're right! But it is confusing!!! I have just been onto the Tusq website and one replacement 1 11/16" nut code PQ-6116-00 has equal centres not equal spaces, but a narrower overall string spacing of 36.45 rather than 37.21mm (StuMac/Martin - proportional centres).

However the Tusq slotted nut 1.69" (1 11/16") that says it is for "Martin style guitars" code PQ-M169-00 has equal spaces and an overall string spacing of 36.99mm.

The devil is indeed in the detail.

[Mirosh]

The issue of string spacing is one more reason I have not installed a new nut: several times I have ordered bone saddles for a Yamaha that come with a nut. All those nuts have narrower spacing than the original nut.

If anything, I would want the same or a bit wider spacing if I were to tackle the job of changing the nut. "Leave well enough alone" works for me.

[DownUpDave]

If you want a solution on how to get a 90* Angle between the back of the saddle and bottom here is what I do. Put a sheet of sand paper on a flat service, glass or granite. Put a block on the paper with a perfect 90* angle, this is your back stop. Now put the nut bottom side on the paper and the back against the block. Move slowly back and forth while keeping firm pressure on the back and light pressure on the bottom.

[rollypolly]

For sanding the bottom the the nut completely flat , you need a sanding tool. They can be had on eBay or Amazon. Basically it’s just a machined aluminum tool that holds either the saddle or nut while you sand against a sanding block.

I have also found the tusq nut and replacement nuts in general on Amazon or eBay , to have too narrow spacing. It’s better for me to get an un slotted bone nut that’s preshaped but allows me to do my own spacing

[JackB1]

Originally Posted by rollypolly

For sanding the bottom the the nut completely flat , you need a sanding tool. They can be had on eBay or Amazon. Basically it’s just a machined aluminum tool that holds either the saddle or nut while you sand against a sanding block.

I'm not sure what this "sanding tool" looks like. Can you provide a link? I need something to insure it stays square.

[Fathand]

Originally Posted by JackB1

I'm not sure what this "sanding tool" looks like. Can you provide a link? I need something to insure it stays square.

https://m.aliexpress.com/item/100500...a-0a455788d5d2

These are the cheapest I found, they are $200 at Stew Mac. It's overkill for doing one nut. You can just glue or carpet tape your nut to a flat square board and sand them together though.