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Hello folks,

I just finished guitar #4, and noticed a slight intonation issue at the first three frets of the high e and B string only. These first three frets are just slightly sharp, maybe 1-2 cents, and then they become right back perfectly in tune down the rest of the fret board. Now this is the first guitar where I've slotted my own nut, as I've previously used the pre slotted bone nuts from Stewmac. My first thought is that I didn't cut the slots on those two strings deep enough, but before I go back in with the file and perhaps make it worse, I'd like to check with some more experienced than myself. Am I right in thinking that the nut slots are a tad too high on those two strings? The overall action is about 1mm higher than I want it to end up at the 12th fret, but I just strung it up two days ago and wanted to give it some time to settle in before lowering it. When playing it isn't totally obvious, but to my ear when playing a C chord in cowboy position I hear the upper C being sharp. So any advice? Thanks!

You are correct if the nut slot is not deep enough the note will go sharper with the extra distance and tension to fret it. A bit of sharpness on the first few fretted notes is normal. The guitar is intonated at the 12 fret. The guitar is tuned open, that is the string is going straight nut to saddle. So the first few frets will be sharp. As you move closer to the 12 fret it is closer to being in tune. Most just live with this as it is common on a lot of guitars.

There are some that adjust the nut location a .5-.8 mm closer to the first fret to make the first few fretted notes play in tune. Basically move some of the saddle compensation to the nut. Other fully compensate the nut to correct the above described intonation error.

As John said, it could be the slot depth. I just corrected the same problem, but the cause of my problem was how I crowned the frets. I didn't have my fret crowning tool perfectly straight, so the crown wasn't dead center. I carefully checked each string with each fret, and re-crowned where needed. It took care of the problem.

Thanks for the replies! I will start by making sure the nut slots are deep enough to be a true zero fret. Also I will check the crowning on the first few frets to be sure that isn't the issue. Thanks again! Many minds are better than one.

I got it! I'm so excited!
So here's what I ended up doing: I made myself a flat pencil by sanding it down length wise until I got to the middle of the graphite. I placed the pencil on the fretboard and moved it side to side drawing a line on the nut, with the idea that the bottom edge of the line I created should be the zero fret. This line revealed that my slots were clearly not deep enough. In fact all six slots were too high. So I filed the slots down to the line. This was scary because I felt like I was going way too deep but I decided to rust the line. I then lowered the action that to 3/32 on the 6th at fret 12 by sanding the bottom of the saddle down. It ended up just perfect. All frets on all strings are in tune and the action feels perfect with no string buzz. This is the best I've been able to get any guitar set up so far and I'm very happy about it:) thanks for your help john and Diane!

Yow! Good story! There is a lot to be learned from this thread. Thanks.

I have a half pencil that I keep to mark the radius on the nut, from the frets as well. It works like a charm. I'm glad you got it straightened out.

good job