humidity and neck bending.

[Whippet]

high humidity causes the neck to concave
low humidity causes the neck to convex

Taking out all string tension factors, is this universal?

Can a luthier make the neck so that it is the opposite of what I mentioned above?

Thanks for all information in advance.

 

[Lobster11]

In a humid environment wood absorbs moisture from the atmosphere and swells; in low humidity it loses moisture to the atmosphere and shrinks. I'm no expert, but I don't see a way around that other than to make the neck out of a different material that doesn't absorb moisture, such as graphite (carbon fiber). That's one of the selling points of Modulus basses.

 

[mdogs]

high humidity causes the neck to concave
low humidity causes the neck to convex

Taking out all string tension factors, is this universal?

Can a luthier make the neck so that it is the opposite of what I mentioned above?

Thanks for all information in advance.

I have no idea what possible difference this would make even if it were possible.

 

[Matt Liebenau]

I doubt you could make a neck that reacts oppositely to changes in humidity then “normal.” I have have several wooden necks that react minimally, if at all, to changes.

 

[Turnaround]

high humidity causes the neck to concave
low humidity causes the neck to convex

Taking out all string tension factors, is this universal?

Can a luthier make the neck so that it is the opposite of what I mentioned above?

Thanks for all information in advance.

If you take out the string tension and the corresponding tension on the truss rod, the neck will become neither concave nor convex.

 

[96tbird]

Opposite? Yes. Put the strings on the back of the neck.

Or flip your bass over.

As said above humidity causes expansion and contraction. Its the string tension that pulls the neck forward.

So in reality no. And it would make no difference if you could because it would still need adjustment as humidity swings. Zero advantage.

 

[Whippet]

I have no idea what possible difference this would make even if it were possible.

You see, one of my basses acted totally different than the others in terms of concave and convex under the same environment than others. These basses were in a humidified cabinet, so the circumstances were the same.

I just wondered other than string tension, what else could have made the neck convex, when all others either stayed the same or concaved.

 

[mdogs]

You see, one of my basses acted totally different than the others in terms of concave and convex under the same environment than others. These basses were in a humidified cabinet, so the circumstances were the same.

I just wondered other than string tension, what else could have made the neck convex, when all others either stayed the same or concaved.

I suppose the way that the grain is oriented could do this.

 

[seilerbird]

i have lived in Florida, the high humidity capitol of the US, for the last six years. I have owned several guitars, several basses and a few ukuleles. Not one single one has any neck warping of any kind.

 

[Whippet]

I suppose the way that the grain is oriented could do this.

but the general understanding is that humidity concaves and lack of it convexes right?

I guess grain orientation could even warp the neck, after all it's cut into a rectangular piece but the original tree was quasi round, so the actual rectangle could be oriented in any 360 degree angle depending on the cut.

I am guessing that luthiers are cutting and setting the neck in the same orientation.

 

[Whippet]

i have lived in Florida, the high humidity capitol of the US, for the last six years. I have owned several guitars, several basses and a few ukuleles. Not one single one has any neck warping of any kind.

warping and twisting is another variable. I figure that has a lot to do with different grain orientations in the length of the neck.

Bending is as the others have said is mositure being trapped or released in the neck and that's expanding the wood. Most likely it's expanding in a uni directional way. Meaning it's not expanding in all directions. I figure that would bloat the entire neck and make the thing twist and warp.

 

[dwizum]

but the general understanding is that humidity concaves and lack of it convexes right?

I would not personally make that generalization. As was mentioned above, high humidity makes the wood swell (get bigger) and low humidity makes it shrink a bit. What that means in terms of curvature depends on a lot of factors. What humidity was the neck built at? Do the neck wood and fingerboard wood expand/contract faster or slower than each other? Is it a fretted neck, and how tight are the frets in the slots? And so on.

Also, I'm not sure what you mean by "same" in this sentence but I'm betting you're pretty much wrong:

I am guessing that luthiers are cutting and setting the neck in the same orientation.

Generally, luthiers will aim for as true a grain direction as they can, in terms of orientation along the length of the neck (you don't want runout). This is for strength but also to keep movement predictable. A rift sawn neck or one with a lot of runout will be much more likely to go wonky when humidity changes, compared to a neck with true grain orientation.

But - that said - there isn't consensus on using quarter sawn lumber vs flatsawn. Many luthiers prefer quartersawn, but some, including big name brands (ie Fender) use flatsawn wood almost exclusively. This choice can change what happens as a neck moves.

And further, even among "perfectly" quartersawn or "perfectly" flatsawn blanks, you have to remember that trees are round, not square. A perfectly cut blank will still essentially have some curve in the grain when viewed from the end, with an "inside" and an "outside" face (ie the face that was towards the heart of the trunk and towards the bark, respectively.) So even if a luthier is selecting only well quartered blanks, they may still end up with necks that behave differently because some were cut "face up" and some "face down."

A multilaminate neck basically averages out the characteristics of each laminate. This usually means it's more stable since you're hopefully placing the laminates so they cancel each other out. Although it's possible to build a laminated bank that acts additively if you stack the laminates all "pointing" in the same direction in terms of the grain - hopefully, no one would do this on purpose though...

 

[Whippet]

I would not personally make that generalization. As was mentioned above, high humidity makes the wood swell (get bigger) and low humidity makes it shrink a bit. What that means in terms of curvature depends on a lot of factors. What humidity was the neck built at? Do the neck wood and fingerboard wood expand/contract faster or slower than each other? Is it a fretted neck, and how tight are the frets in the slots? And so on.

Also, I'm not sure what you mean by "same" in this sentence but I'm betting you're pretty much wrong:



Generally, luthiers will aim for as true a grain direction as they can, in terms of orientation along the length of the neck (you don't want runout). This is for strength but also to keep movement predictable. A rift sawn neck or one with a lot of runout will be much more likely to go wonky when humidity changes, compared to a neck with true grain orientation.

But - that said - there isn't consensus on using quarter sawn lumber vs flatsawn. Many luthiers prefer quartersawn, but some, including big name brands (ie Fender) use flatsawn wood almost exclusively. This choice can change what happens as a neck moves.

And further, even among "perfectly" quartersawn or "perfectly" flatsawn blanks, you have to remember that trees are round, not square. A perfectly cut blank will still essentially have some curve in the grain when viewed from the end, with an "inside" and an "outside" face (ie the face that was towards the heart of the trunk and towards the bark, respectively.) So even if a luthier is selecting only well quartered blanks, they may still end up with necks that behave differently because some were cut "face up" and some "face down."

A multilaminate neck basically averages out the characteristics of each laminate. This usually means it's more stable since you're hopefully placing the laminates so they cancel each other out. Although it's possible to build a laminated bank that acts additively if you stack the laminates all "pointing" in the same direction in terms of the grain - hopefully, no one would do this on purpose though...

Thanks for the indepth explanation. This is the information I was looking for.

When I wrote ''same'', I was referring to the grain orientation.

The face up and face down could be one of the reasons why one of the guitars acted differently, along with what you said about the expansion of the finger board.

Once again, thanks for the detailed explanation.

 

[Turnaround]

warping and twisting is another variable. I figure that has a lot to do with different grain orientations in the length of the neck.

Bending is as the others have said is mositure being trapped or released in the neck and that's expanding the wood. Most likely it's expanding in a uni directional way. Meaning it's not expanding in all directions. I figure that would bloat the entire neck and make the thing twist and warp.

As water is absorbed into the wood, it will expand in length, width and thickness. On flatsawn wood, the major change is in the width of the board, but there is a change in length about 10% of the change in width. Change in thickness is somewhat less. In quartersawn, the length change is the same as flatsawn, but the width shrinkage is much less, at the expense of change in thickness which is greater than flatsawn.

 

[Whippet]

As water is absorbed into the wood, it will expand in length, width and thickness. On flatsawn wood, the major change is in the width of the board, but there is a change in length about 10% of the change in width. Change in thickness is somewhat less. In quartersawn, the length change is the same as flatsawn, but the width shrinkage is much less, at the expense of change in thickness which is greater than flatsawn.

I forgot who and where, but I read an interview where the luthier (probably well known to be in an interview) said that he preferred flatsawn to quartersawn due to improved tone. I know this is a totally different topic and a controversial one for that matter.

He said that a good flatsawn is just as stable as a quatersawn. I have no idea if this is true or not, but I would think that what you wrote above in change in dimensions given changes in humidity is accecpted as a fact by most people.

Anyway it is interesting to hear peoples' different approaches to building and wood choice

 

[Killed_by_Death]

My solution was having instruments with:

A - Titanium reinforcement bars in the neck

B - Roasted maple neck


edited to Titanium bars:

 

[Whippet]

My solution was having instruments with:

A - Titanium reinforcement rods in the neck

B - Roasted maple neck

Titanium really helps. The Ibanez with titanium rods outperform stability of basses costing over 5-8 times more Put it this way, my Ibanez is more stable than my Dingwall Prima, MTD A. Gouche, F bass, etc etc.

I just wonder if Titanium affects the tone in some way. Not necessarily negative but in any way.

 

[Killed_by_Death]

Of course it affects the timbre.
I firmly believe that great timbre is directly related to the stiffness or hardness of the material the strings are mounted on.

Furthermore, the less mass it takes to provide this strength, the better.
Titanium would actually be less dense than the wood it replaced, but with greater strength. It's just a bonus that it's also non-Ferrous.

Also, the roasted maple neck on my Ibanez RG makes it sound better than a very similar model with the same pickups & a non-roasted neck-through.

 

[Killed_by_Death]

Another bonus to Titanium or roasted is that they're better for down-tuning
I can tune either down to C# & they remain playable.

 

[Whippet]

I will check out the RG with the roasted neck and titanium. BTW, which model is your?