String Jumping/ Nut Angle

[kowgiirl.up]

I just finished my SM Concert and I have the "C" string that jumps off the nut while plucking/picking/strumming. All other strings stay in place. I am using the stock strings that came in the kit.

Should I post here on in the Luthier/building thread?

 

[Oldscruggsfan]

I can’t imagine any root cause other than that the C string nut slot is either:
A) not nearly deep enough which (secondarily) means action is far too high at the nut;
B) too wide and tapered on at least one wall, which allows the string to “roll out” as you pluck it.

OR, the C string tuning machine post hole is a good bit (say 3mm) farther from (above) the headstock as compared to the G, E and A tuner posts’ string holes, which removes physical leverage at the nut regardless of how much tension is on the string.

 

[kowgiirl.up]

I can’t imagine any root cause other than that the C string nut slot is either:
A) not nearly deep enough which (secondarily) means action is far too high at the nut;
B) too wide and tapered on at least one wall, which allows the string to “roll out” as you pluck it.

OR, the C string tuning machine post hole is a good bit (say 3mm) farther from (above) the headstock as compared to the G, E and A tuner posts’ string holes, which removes physical leverage at the nut regardless of how much tension is on the string.

Thanks. I'll give all those a checking out.

 

[rrieth]

Disappointment! I thought this was about a variation on jump-rope.

 

[Oldscruggsfan]

@rrieth - I was also confused by the thread title. I first assumed it was a new variation on Travis picking.

 

[Island Jim]

Bring your uke up to tune, press down each string individually at the 3rd fret. If the nut slots are the right depth the strings should just clear the first fret, maybe the thickness of a piece of paper. If they are much higher you can carefully lower the slots, checking as you go!

 

[kowgiirl.up]

There! I edited the thread title so maybe you all won’t think that it’s about a new way to play

After closely looking at the nut we discovered that the nut is not seated in its place. It is kicked out where at the bottom and if you hold it up to the light you can see that it is not tight against the fretboard.

I must have made a mistake when I adjusted the nut height and did not sand it flat- I am not sure.
The nut is not glued down so I can slip it out.

If I need to sand the nut so it’s square can I shim to bring it back to the correct height? If I can shim, what would I use to I shim with?

 

[kowgiirl.up]

@Island Jim , I was typing while you were posting. Thank you for posting the picture

 

[TerryM]

@Island Jim , I was typing while you were posting. Thank you for posting the picture

Are you left handed, or is that second picture reversed? Regardless, it looks like the largest string (second from left) is sitting high in the nut, in addition to the nut angle.

 

[Oldscruggsfan]

All 4 nut slots look far too shallow and I agree with @TerryM about the 2nd string from left. Try Matt Stead’s credit card test:
While holding the uke vertical (headstock down), slide a gift card under the strings and let it drop toward the nut. If nut slot depth is correct, the card should “break” (stop) at the 3rd fret.
Were I in your shoes, I’d sand off the base of the nut to lower action but that won’t fix your problem. Action at the nut appears so high that you will also need to use a needle (jeweler’s) file or actual nut file to deepen each of those slots a bit.

 

[kowgiirl.up]

Are you left handed, or is that second picture reversed? Regardless, it looks like the largest string (second from left) is sitting high in the nut, in addition to the nut angle.

I am right handed.
Second picture from right to left G, C, E, A

 

[Island Jim]

It looks like you have a few issues. You need to sand the bottom of the nut so it is at right angles to the face that butts up to the fingerboard. You then need to make sure the spot the nut sits on is also flat. Get both of those problems solved and it might bring down the height of the nut. If the nut is too high but flat don't mess with the bottom, make the nut slots deeper. This will make it easier to play and keep the string from jumping out of the slot.

 

[TerryM]

I am right handed.
Second picture from right to left G, C, E, A

Must be an optical illusion. The 3rd string from the right in the photo looks like it's the fattest, which should be C.

 

[Island Jim]

High g so the c should be fattest!

 

[kowgiirl.up]

@TerryM good eye! I had the two swapped. I didn't know any better but now I do.

@Island Jim "C" should be the fattest!!!

I now have the strings swapped. The hubby checked the level on the nut, fingerboard and the nut seat. We took just a bit (I don't know the measurements) off of the fingerboard where the back of the nut would snug up against. We then took a bit off of the bottom of the nut a little at a time until the nut no longer rocked back and forth and no gaps could be seen with the magnifier. It seems good now. We, (well he ,I just held the nut) filed the string slots with his torch tip files (he measured them with his calipers to make sure they were correct for the slot). We just barely, barely filed. I would bet that the string slots could be taken down more but being novices I was afraid to go more.

I strummed uke and the "C" string stayed put. I will practice on it and see how it goes.

Thanks for getting me all squared away. I appreciate it!

 

[Oldscruggsfan]

Not meaning to be a pest, but your best gauge for proper action at the nut is the credit card “drop” test I mentioned. Based on those photos, strings need to be far lower to be able strum clear 1st position notes.

 

[kowgiirl.up]

Not meaning to be a pest, but your best gauge for proper action at the nut is the credit card “drop” test I mentioned. Based on those photos, strings need to be far lower to be able strum clear 1st position notes.

You’re not being a pest one little bit. Sometimes I need prodded.

I saw your post last night, found a card and did the test. That card dropped like a hot potato clear to the nut. No slowdown whatsoever.
As is, those 1st notes are a real bear to press down for my index finger so making more adjustments should help I hope.

I haven’t glued the nut so I can pop it back out to fix it. I can just loosen the strings to slip the nut out to sand the slots. I just learned that Stew Mac says 1/3 of the string diameter stick up above the nut.

 

[Wiggy]

You’re not being a pest one little bit. Sometimes I need prodded.

I saw your post last night, found a card and did the test. That card dropped like a hot potato clear to the nut. No slowdown whatsoever.
As is, those 1st notes are a real bear to press down for my index finger so making more adjustments should help I hope.

I haven’t glued the nut so I can pop it back out to fix it. I can just loosen the strings to slip the nut out to sand the slots. I just learned that Stew Mac says 1/3 of the string diameter stick up above the nut.

That is called "action at the 1st fret." As Island Jim showed above, hold each string between the 2nd and 3rd fret and check the gap between it and the top of the 1st fret. It takes a bit of dexterity, but while fretting use another finger to press down on the string directly over the 1st fret.

There should be a very small amount of motion to touch it to the top of the 1st fret. It is easy to see. The larger the gap, the harder it is to play. If there is no gap, you will have fret buzz - that is very bad. This is the nut slot depth adjustment.

<edit> TMI: The nut slot depth is relative to the 1st fret and the saddle height. Many factory nuts are higher than desired and do allow the slots to be adjusted down. IME, factory saddles are "close enough." But if the nut is not high enough to begin with, it would need to be replaced.

 

[Oldscruggsfan]

You’re not being a pest one little bit. Sometimes I need prodded.

I saw your post last night, found a card and did the test. That card dropped like a hot potato clear to the nut. No slowdown whatsoever.
As is, those 1st notes are a real bear to press down for my index finger so making more adjustments should help I hope.

I haven’t glued the nut so I can pop it back out to fix it. I can just loosen the strings to slip the nut out to sand the slots. I just learned that Stew Mac says 1/3 of the string diameter stick up above the nut.

The reason I’m so enthusiastic about Matt Strad’s card drop test is that I had (for nearly 18 months) also believed first fret action to be correct on my uke. I was amazed when my gift card test had the same result as yours.

You’re fortunate in being able to sand off the base of the nut. I was unable to get the nut to pop off which left no alternative than to file the string slots. Card now stops and the 2nd fret and I’m reluctant to file those nut slots any deeper.

Meanwhile, 1st position chords are soooo much easier to nail now.

 

[kowgiirl.up]

After several in's and out's of the nut I have gotten pretty good at loosening and tightening the strings

Between the hubby and I (mostly him) we have the nut so it sits nicely by sanding the bottom after we adjusted the string slots to proper depth.

The credit card will stop at the 3rd fret wire. It's not a perfect stop on all the strings due to me not paying attention when I first sanded the nut which caused problems for the "G" string that would become too low if we took more off the nut.

I am not going to glue the nut just yet. I may decide that I want to start over with a new nut. If I glue now I won't have that option so easily available.