Luthier Tips du Jour Mailbag - String Height at the Nut

youtube P2cM80j3Uwo

In this episode, Robbie O'Brien shows how to adjust string action at the nut.

Video Transcription

[on-screen text reads: Luthier Tips du Jour Mailbag]

Mailbag question: I'm making a new nut for my guitar and I'm having trouble getting the action correct

Robert O'Brien: Today's Tips de Jour Mailbag question comes from a viewer in Florida. "Robert, I watched your Tips de Jour video on nut and saddle making. I'm making a new nut for my guitar. However, I'm having trouble getting the action correct after making the new nut. What do you suggest? Terry, in Florida."

Well, Terry, when making a new nut, it's very important that the action matches exactly or as closely as possible the action you had in the old nut. That way, the player doesn't notice any difference between the old nut and the new nut. When I make a new nut for a client's guitar, the first thing I do is notate the action that the old nut had. That way, when I slot the new nut, I can know exactly what it needs to be slotted to so I have the correct action at the nut. Let me show you how I do that.

Notate the action on the existing strings

Terry, like I said, I'm going to make a note of what the action is on the existing strings. On this particular guitar, there are 10 strings. It's a harp guitar, so I have 10 strings coming across that nut. It's very important that I know exactly what the height is off the fret so that the new nut and the new strings have exactly the same height. What I'm going to use is a dial caliper known as a string height gauge. I got this tool from LMI. I can place the tool over the string and then hit the plunger, and it tells me exactly the height of the string off the fret. I'm going to do that for each of the 10 strings on this guitar and make a note of that. Then, I'm going to make the new nut, install it, and I'll show you how to dial the action in for the new nut.

Dial in the action at the nut

Once I have the new nut made and pre-slotted, I'm now going to come in and dial in the action at the nut. I do that by placing the tool over the string. Turn the dial to zero, and then hit the plunger. The string is coming in at 0.019", and I need to get it down to 0.015". We're very close. With my calipers, I check to see the exact diameter of the string, and then I choose my appropriate nut file for that string. I then use the file very lightly. Take a little bit out of the nut slot.

Now, I've placed my string height gauge again over the string, zero it out, and when I check it, I'm coming in right at about 0.016". That's pretty close. It needs to be 15, but 0.016" is close enough. The important thing is that it's not buzzing. It's not laying on the fret [Robert plays the string with his finger to hear if it is buzzing]. It's not. Now, I need to walk across the other nine strings and dial all of those in.

Terry, from Florida, thank you for your question. With the information I provided you in this video and the string height gauge from LMI, you should be able to dial in the action of the nut very precisely. The player should notice no difference in action between the old nut and the new nut.

[on-screen text reads: More Luthier Tips and online courses available at]



Robbie O'Brien

Luthier and Instructor, Lutherie Academy