Nut Slot Query

mr79

mr79

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Hi all,
Just a quick one about nut slots - I was always lead to believe that nut slots should be cut ever so slightly wider than the string they are going to support, not so tight they bind, not so wide they let the string slip sideways when playing. I've been wanting a set of nut files for ages, but can't afford them, and use those welding tip files in the meantime.

Recently I picked up a Pono concert as a replacement for a baritone I didn't get along with. The Pono has excellent intonation, but I noticed the nut slots are completely different to all other string instruments I've tried - each slot is exactly the same size, the same depth, and the same shape (a quite wide semi-circular cut into the nut, not really holding the string at all which just sits in the bottom of the circle). I assume it is the original nut.

So is all that effort I took making perfectly sized slots for other people's mandolins, guitars and ukuleles wasted?! Could I have just cut each slot with the same round needle file? I'm confused!

Anyway, your thoughts'd be appreciated.
Thanks!
 
Your efforts were not wasted. Nut slots are supposed to be exactly as you described them. Anything else leads to instrument inefficiency, unwanted noise, snapped strings and the list goes on.
 
I learned from a very good Italian luthier that the slot must be exactly the same diameter of the string and accommodating it to half.
so I have always gotten good results
capotasto_slot.jpg
 
That's what I thought, yet the Pono sounds good, with excellent intonation. It is quieter than I expected, and I'm wondering if the nut slots might be the reason? I've just checked them all, and while the C string slot is nearly the right size, the others are considerably wider (the A-string slot is nearly twice the width of the string diameter) and uniform in size to each other. Curious...
 
I think it can also depend on the inclination of the headstock,
the greater the inclination, the greater the pressure of the strings on the nut, and so the strings are less likely to move

you check it on the Pono
 
Sven said:
Also the slots should be angled down more steeply than the direction of the strings, I think I have mentioned this before.

View attachment 68533
Click to expand...

SteveZ said:
Definitely! Great picture of the correct situation. Also, rounding the contact point helps prevent string gouging during tuning.
Click to expand...

I shall be applying all these to the new nut I'm now making!
 
View attachment 68533

Excellent diagram. So, the hangle of the huvadud and the stringleslotten indecreases the kondatactin of the strangledangle on the ooversaddledoodle. ??






.
 
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And angle them at the nut so they are in line with the tuner peg tangents :) so that there is no side friction.
 
Are you mocking my Vikingese?! Beware - I might swing by for a quick, erm, pillaging.

Ken's right about the other angles, an easy way to a classy detail.
 
Czutney said:
That's what I thought, yet the Pono sounds good, with excellent intonation. It is quieter than I expected, and I'm wondering if the nut slots might be the reason? I've just checked them all, and while the C string slot is nearly the right size, the others are considerably wider (the A-string slot is nearly twice the width of the string diameter) and uniform in size to each other. Curious...
Click to expand...

It doesn't surprise me at all. If you look at the opposite end (the saddle) it has no grooves at all, yet it doesn't lead to any problems. There is a difference in the break angle but don't forget we are referring to something without grooves compared to something with grooves. A string will still tend to sit firmly in a round bottomed slot (under tension) even though that slot is wider than it should be. I've been using a single round needle file for all string gauges. I have done so for decades. It's highly unlikely that I get the groove perfectly sized to the string. They are almost certainly a little wider than the norm. I've never experienced any problems or the so called fatalities that have previously been mentioned.
It can't possibly affect the tone or volume. As soon as you fret a string the Nut is completely taken out of the equation anyway.
 
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Michael N. said:
I've been using a single round needle file for all string gauges. I have done so for decades.
Click to expand...

Is it possible to share a picture of, and/or a link where to buy such a magical tool?

Thanks in advance,

Booli :)
 
Booli said:
Is it possible to share a picture of, and/or a link where to buy such a magical tool?

Thanks in advance,

Booli :)
Click to expand...

I buy them locally, from a Jewellers suppliers. You are looking for a decent Grobet/Vallorbe round needle file. 4" or 5 1/2". Cut 2 - which is medium. They aren't cheap but they are well made. One file will slot many hundreds of top Nuts
These come to a very fine point, very easily broken. So put very, very little 'pressure' on them when using - especially the tip. You have been warned! I use a zona saw (junior hack saw will do) to establish the initial groove. then carefully use the Grobet to turn it into a rounded slot. A bit of practice and you will soon get the hang of which part of the file to use for the particular string. I regularly slot strings that go down to 0.4 mm Nylgut right through to heavy wound strings, all with the same file. Avoid making the slots too deep, simply because there is no need to. Slotting with such a file should only take a few minutes. In fact once you are practiced it's probably quicker than using gauged files. Ebony is OK for using as practice material. In fact Ebony is OK for Top Nuts anyway, especially instruments with unwound strings.
Slots are finish polished with a few strands of sewing cotton dipped in T-cut.
 
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Booli said:
Is it possible to share a picture of, and/or a link where to buy such a magical tool?

Thanks in advance,

Booli :)
Click to expand...

I've been using "cigar box guitar tool" files for quite a while. The price is <US$10 and they work great. They are actually welding rod tip cleaners of varying diameters sorted and linked into a single box. They are easy to use and it's just a matter of matching the appropriate file to the string involved.

EBay and other sources have them (no financial interest!).

image.jpg
 
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Why make a new nut?? If its working....I'd leave it alone. The nut will only affect tone on open strings, so if you find the Pono quiet on fretted strings then it isn't a nut problem. As long as it doesn't buzz or get too twangy on open strings it should be fine.
(Although, I do agree that the best practice is to size nut slots for the string and angled so the string is held on a small contact point.)
 
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