neck movement questions

[Flintc]

I have a question I hope you luthiers can help me with. I bought a bass with a wide neck (7-string, 18mm spacing), built this year. When I got it, the frets extended past the side of the neck, so I had them filed down. A month later, they were again past the edge, so I had them filed again. Now another month has passed, and I can feel just a trace of extended fret, not enough to be concerned about, but it indicates that the neck is still moving.

The problem is, the fingerboard itself might be moving. From week to week, one string might develop a buzz over part of its range for a day or two, then be OK but another string develops a buzz. I've been dealing with this by making tiny adjustments in the neck truss rod (when all strings change action, for example), and tiny adjustments to the bridge saddles (when every string is great except one). The neck seems to be drying out, but also it's like internal wood stresses changed when the wood was cut, and haven't fully stabilized yet.

Is this normal? Will it stop moving? After how long? When strings are removed to dress frets, then replaced, is it normal for the neck to bow up? Is it bad for strings to be removed for a few hours? I never know exactly what bass I'm going to be picking up today! I'm just trying to educate myself about this stuff.

[Son of Magni]

The fret ends issue is due to the fretboard shrinking which is pretty normal especially if it's ebony and especially if you live in a dry climate.

The neck adjustments is a different issue. I also consider this normal with a new instrument and it may go on for 6 months or even up to a couple years. The wood is just "getting used to being a neck", and it takes a while to settle in. The adjustments will become less and less often over time.

[Yellow]

Wow, thats a lot of movement, how is the neck finished?

If the frets are sticking out my guess it is shrinking, shrinking is from drying, so the fretboard wood and may be the neck wood was at a higher moisture content when it was built, not necessery green wood, although that is possible too.

7 string is a wide neck, green wood or wood that has been stored in a higher then optimum moisture conditions can shrink to up to 1/4 inch per foot in extreme cases.

It will stabilize in your climate after a month or two so you should be at the end of it now. It will help to prevent its movement if it is well sealed(finished) Imagine after filing down those frets if it expanded as much (unlikely) you 'd be short of frets on the sides.

Thats my 2c as a woodworker, real luthiers will respond soon I am sure.

[Rodent]

Originally Posted by Yellow

real luthiers will respond soon I am sure.

guess that rules me out from having anything to say here

all the best,

R

[DavidRavenMoon]

There's only one truss rod in that wide neck? Any graphite in there?

It seems the fingerboard might be shrinking, which as SoM said is normal. But it might also be that the wood wasn't seasoned enough. If this is the case, it might not be as level as it was when it was first fretted, and might still be changing.

You might have to live with it a while until it settles down, and then either have the frets leveled, or if that doesn't help, you might need to have the fingerboard leveled and refretted.

Before I built my first basses, I had an Ibanez SoundGear. That neck was different almost every day, just like your bass. That's not the way a neck is supposed to be, and I used that as an example of what I didn't want my necks like!

When you take the strings off, it's normal for the neck to back bow slightly, since the truss rod has tension, but there's no strings on to counteract that. A back bow is away from the fret side of the fingerboard. It's not normal to have it up bow.

I usually remove one string at a time, but it doesn't hurt to have no strings on to clean the fingerboard before fretting. If you are going to have the bass without strings for an extended period of time (like 24 hours) I would loosen the truss rod.

Another thing to remember is when adjusting your neck, if you have to make any big moves, don't rely on the truss rod to straighten the neck. It's not designed for that. The correct way is to clamp the neck straight and then tighten the rod. In a pinch you can bend it over your leg... like they used to show in the old Rickenbacker instruction sheets.

[Flintc]

Wow, thats a lot of movement, how is the neck finished?

I don't know. The fretboard is birdseye maple, and the neck itself is ash and wenge, 5 laminations. I don't see any sign that the fretboard is soaking up any oil (I have a pao ferro fingerboard that has soaked up a LOT of oil in a similar amount of playing time).

7 string is a wide neck, green wood or wood that has been stored in a higher then optimum moisture conditions can shrink to up to 1/4 inch per foot in extreme cases.

The neck is about 5 inches wide at the 24th fret, but I haven't seen anywhere near an eighth-inch of shrinkage. Probably no more than 1 or 1 1/2mm at the most. But a fret only needs to stick out a couple of thousandths to abrade your skin.

There's only one truss rod in that wide neck? Any graphite in there?

I'm told that there are two graphite rods in addition to the single truss rod. However, from sighting down the neck I can see that the treble side is almost perfectly flat with a tiny hint of S curve in it, while the bass side is bowed perhaps as much as 1/8 inch.

When you take the strings off, it's normal for the neck to back bow slightly, since the truss rod has tension, but there's no strings on to counteract that. A back bow is away from the fret side of the fingerboard. It's not normal to have it up bow.

Maybe I wasn't very clear. The strings have been taken off twice for fret dressing, but then replaced. The forward bowing occured very slowly over the two days after the strings were replaced.

Another thing to remember is when adjusting your neck, if you have to make any big moves, don't rely on the truss rod to straighten the neck. It's not designed for that. The correct way is to clamp the neck straight and then tighten the rod.

Thanks, hopefully I'm getting the hang of this. Yes, I've been manually putting a bit of pressure on the neck in the direction I want to adjust it, so the truss rod doesn't have to do all the work. But the moves have been very very small, changing overall action maybe 1/8" on a 35" scale neck.

This bass cost me about two years of dedicated savings, and it sounds like a dream. I'm just concerned about the slight movements in the fingerboard. Raising the C string bridge saddle about half a millimeter eliminated the buzzing between the 2d and 8th frets, which pretty much makes the whole bass right except for the 13th fret of the F string, which is buzzing somewhere between there and the nut when I fret it. I don't have any clue what to do about that except, when everything seems to have stabilized, to have all the frets leveled at once.

[Son of Magni]

Originally Posted by Rodent

guess that rules me out from having anything to say here

all the best,

R

Clearly it rules me out too

[Flintc]

Nobody is ruled out who's less ignorant than I am. Which is all of y'all, believe me.

[Yellow]

Hey we all learning here as we go, I am amaized how much great stuff I learn here on TB.

[DavidRavenMoon]

Originally Posted by Flintc

I'm told that there are two graphite rods in addition to the single truss rod. However, from sighting down the neck I can see that the treble side is almost perfectly flat with a tiny hint of S curve in it, while the bass side is bowed perhaps as much as 1/8 inch.

On my 5 strings, I use two truss rods with graphite between them. These are maple/purpleheart necks with 7 laminations. They are only about 2.75 wide at the 24th fret and they are 34 inch scale. I'd never make a neck that wide with one truss rod. As it is I have to adjust each side separately. I always figured I over built my basses because I worry too much... but it's paid off.

Originally Posted by Flintc

Maybe I wasn't very clear. The strings have been taken off twice for fret dressing, but then replaced. The forward bowing occured very slowly over the two days after the strings were replaced.

Where they the same gauge and brand strings? Sounds like the rod needs to be tightened again.

Originally Posted by Flintc

This bass cost me about two years of dedicated savings, and it sounds like a dream. I'm just concerned about the slight movements in the fingerboard. Raising the C string bridge saddle about half a millimeter eliminated the buzzing between the 2d and 8th frets, which pretty much makes the whole bass right except for the 13th fret of the F string, which is buzzing somewhere between there and the nut when I fret it. I don't have any clue what to do about that except, when everything seems to have stabilized, to have all the frets leveled at once.

If it keeps up I would ask the builder to remove the fingerboard and install two truss rods and more graphite. Sounds like a big deal, but it shouldn't be. I'd also add thin laminations under the fingerboard. Even two layers of veneer stiffens it up quit a bit.

For that amount of money you shouldn't have these issues.

[DavidRavenMoon]

Originally Posted by Son of Magni

Clearly it rules me out too

Hey, you make some cool basses! I love the hardware.

We never, ever, stop learning. That's why I'm here... to learn new stuff.

That's what life is all about!

[Flintc]

I'd never make a neck that wide with one truss rod.

Most people I've spoken to have been amazed that such a wide neck would be built with a single truss rod, but that's how it is.

Where they the same gauge and brand strings? Sounds like the rod needs to be tightened again.

They were the original strings, still on the bass. And after each fret job, I tightened them. Which seems to work, except for the fingerboard movement.

If it keeps up I would ask the builder to remove the fingerboard and install two truss rods and more graphite. Sounds like a big deal, but it shouldn't be. I'd also add thin laminations under the fingerboard. Even two layers of veneer stiffens it up quit a bit.

For that amount of money you shouldn't have these issues.

Sigh. I sincerely hope it settles soon. I'd hate to have the neck rebuilt. But I agree, a $4000 bass shouldn't be such a hassle. Maybe I've got it pretty much stable now.