C string buzz- adjust nut

I'm fairly positive the problem is the slot on the nut. The buzz is only heard when the C string is played open. I think it just has too much room or something. The strings I'm using are pretty thick and dug the slot a bit wider. I'd prefer not to replace the nut, as it's wood and matches the uke nicely. Is there anything else I can do?

I'm wondering if there actually is not enough room for the string or if the groove is rough. If you're on the verge of replacing the nut anyway, you might first try sanding the groove a little to make it slightly larger and smoother.

On the other hand, if the problem is that the groove is too deep (or you made it too deep by sanding it!), small drops of super glue followed by gentle sanding can raise the height of the groove. Just make sure you protect your uke from the inevitable unwanted drips and threads of glue.

Good luck.

I think it may just be rough. It's not vibrating against a fret. Is there any way to know for sure that it's at the nut?

Fretting at the first fret is a good indicator. If that eliminates the buzz then the chances are that the rattle is either at the nut itself, or at the first fret because the nut slot is too low. Either way, fix the nut and the buzz will likely be cured.

Try this:

• Hold the string down at the 3rd fret.
• While holding it down at the 3rd, look at where the string passes over the 1st fret. If the string is actually touching the 1st fret then the nut slot is probably too low/deep. There should be at least a tiny hair or paper's breadth of clearance between the string and the top of the fret. Exactly how much will vary between instruments.

If there is a gap then perhaps it's the shape of the slot.

If the slot is cut using a file that leaves a flat bottom then if the slot is too wide the string may buzz. If a proper nut file is used then the slot has a nice rounded bottom and even if the slot is wider than the string there is often no buzz.

Also, the slot should angle back and down towards the tuners. If it slopes the other way - even for a millimetre at the fretboard side of the nut, then the string won't break cleanly over the edge of the nut at the fretboard side. The same thing can happen if the slot is dead flat and horizontal. It really does need to slant back to the headstock.

It may also be worth changing the offending string and, while it is off, give the slot a good clean.

Good luck.