Reverse bow question

[notCardio]

What would cause several of my guitars to develop a reverse bow?

In all 40 years, I think I've only ever had one guitar develop one, but in the last couple of months, it's happened to at least 5.

What's the deal?

 

[muttley600]

do you mean no relief or back bow?

If it is happening across several instruments you need to look at increase in humidity. I'm assuming you haven't changed string gauge on them all or similar?

 

[notCardio]

do you mean no relief or back bow?

If it is happening across several instruments you need to look at increase in humidity. I'm assuming you haven't changed string gauge on them all or similar?

Right, no reief or back bow. So you're saying they are too dry, correct? I could understand that, but it just seems weird that it's never happened like that before. I guess we supposedly have had a much colder than normal winter. So, would a regular forward bow be caused by too much humidity, or are there lots of reasons for that?

If I re-humidify them, will the bow correct itself somewhat? Do I need to wait until that happens before tryng to have it corrected with a truss rod adjustment?

Thanks.

 

[muttley600]

Normally too much moisture. The f/b takes in moisture the back of the neck not so much. When wood takes on moisture it expands so in the case of a guitar neck the back of the neck is compressed.

The solution is to reduce moisture content or have it setup so that the guitar is balanced for that level of humidity by slightly slacking off the truss rod.

 

[notCardio]

Normally too much moisture. The f/b takes in moisture the back of the neck not so much. When wood takes on moisture it expands so in the case of a guitar neck the back of the neck is compressed.

The solution is to reduce moisture content or have it setup so that the guitar is balanced for that level of humidity by slightly slacking off the truss rod.

I'm pretty sure that my guitars had been exposed to a decrease in humidity when this happened. I don't understand it. They had been kept in a much cooler basement most of the time, which, while dry, isn't nearly as dry as where they are right now, which is also considerably warmer as well as drier. They also are on their sides in the cases now, whereas they are normally on end in their cases.

I just don't want to go adjusting them and then have problems when I take them back home to their old environment.

 

[muttley600]

I'm pretty sure that my guitars had been exposed to a decrease in humidity when this happened. I don't understand it. They had been kept in a much cooler basement most of the time, which, while dry, isn't nearly as dry as where they are right now, which is also considerably warmer as well as drier. They also are on their sides in the cases now, whereas they are normally on end in their cases.

I just don't want to go adjusting them and then have problems when I take them back home to their old environment.

Ignore tempreture unless it is extreme. Temp just speeds up or slows down the rate at which timber gains or loses moisture. Concentrate on humidity.

There really is no other way that a guitar will behave other than to expand when it takes on moisture and contract when it loses moisture. It's just the way it is.

There's really only three things that can cause what you describe, a decrease in the tension of the string set, increased back bow from the truss rod and finally fluctuations from the environment that the guitars are kept in. Think about it, the tension in the neck must have changed, what changed it? If it happened on more than one guitar it has to be the environment and moisture content specifically.

 

[notCardio]

I know what you're saying must be true, but it's just that it doesn't fit with what I think is true of the environment. I will check the humidity in both places, though, just because it's bugging me that it's not making sense. I hate it when that happens.

Thanks, man.

 

[muttley600]

I just don't want to go adjusting them and then have problems when I take them back home to their old environment.

Have I missed some thing? These guitars are on a road trip of some sort.

 

[muttley600]

I know what you're saying must be true, but it's just that it doesn't fit with what I think is true of the environment. I will check the humidity in both places, though, just because it's bugging me that it's not making sense. I hate it when that happens.

Thanks, man.

No worries.

The answer is usually quite simple. Most of this stuff is. The trick is to get all the VP crap out of the way and concentrate on how stuff behaves.

Timber reacts to moisture that's all there is to it really. If the humidity is constant it is down to some thing else. If the string tension is constant it's down to something else, if the truss rod is working correct5ly it's down to something else..

You get the picture

 

[notCardio]

No, I've just been staying with my mom, which is out of town, for a couple of months while she went through radiation. The guitars I took with me were all afflicted. And no, I drove (she's only an hour and a half away), so they didn't fly.

 

[muttley600]

No, I've just been staying with my mom, which is out of town, for a couple of months while she went through radiation. The guitars I took with me were all afflicted. And no, I drove (she's only an hour and a half away), so they didn't fly.

So you have been staying with mum for extended periods (days, weeks) and took a few guitars along and these are the ones that have issues?

Also, I hope mum is doing well dude.

 

[notCardio]

She's fine, thanks.

Yeah, but I haven't been taking them back and forth, I just brought them and left them here.

 

[muttley600]

She's fine, thanks.

Yeah, but I haven't been taking them back and forth, I just brought them and left them here.

Right, Thing is that two houses on the same street can have two completely different micro climates. One has double glazing the other has wooden sashes. One has aircon and central heating while the other has ceiling fans and opn fires. You get the picture.

It really can make a big difference seriously. Not saying your place or your mums are bad just that in all likelihood your mums place has a lot more ambient humidity..

If you are going to ship these guitars back to your gaff hold fire for now and let them settle. If they are going to stay where they are then a little truss rod tweak would most likely do the job.

 

[Zaphod B]

The trick is to get all the VP crap out of the way and concentrate on how stuff behaves.

So, what are you sayin'?

 

[muttley600]

So, what are you sayin'?

.................

Nothing I'm Nay-sayin'.

 

[Zaphod B]

I'm disappointed that you failed to mention the possibility of the non-resonant qualities of the theoretical dead spots affecting the structure of the neck wood.

 

[muttley600]

I'm disappointed that you failed to mention the possibility of the non-resonant qualities of the theoretical dead spots affecting the structure of the neck wood.

Thats strings dummy. Dead spots are for strings. Have you learned nothing.

 

[Zaphod B]

Thats strings dummy. Dead spots are for strings. Have you learned nothing.

Well, it's my experience - from having been up on a pole and not feeling a guy wire do anything when I hit it with a pencil, that it's possible that the string vibrations - or for the dead spots, lack of vibration - cause physical changes in the wood. Why else would acoustic guitars sound better with age? Everybody knows that.

Anyway, you are just an arrogant self-appointed expert and you have no idea what my experiences are and my opinions are just as valid as anyone else's.