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Can't keep my necks from bowing

Falkner

Falkner

Mar 5, 2008
239
2
#1
Alright, this is driving me crazy. I can’t keep my bass’ necks from constantly bowing. Every few weeks they develop too much relief and I have to tighten the truss rod to get it straight again. The problem is, all my truss rods are maxed out and they’re still bowing! I loosened the strings and got them to tighten a little more, but it’s not enough and I don’t want to break the truss rod. I’ve had this problem on almost all my basses (My old Yamaha RBX170, Squier jazz, and now my beloved Yamaha A2 is starting this). My guitars and my SX jazz are unaffected and have straight necks which I rarely have to adjust, so I don’t think it’s a humidity issue.

Am I just really unlucky and got basses with bad necks/truss rods or is there something I’m not thinking of that I can try? I'll admit to still being a bit noobish to setting up instruments.
 
#2
Falkner said:
My guitars and my SX jazz are unaffected and have straight necks which I rarely have to adjust, so I don’t think it’s a humidity issue.
Click to expand...
SX vote of :bassist: :D !!
My P/J SX and I thank you for the durability report.

As far as "the others":

Do they have similar strings & tension as the SX?
Are you SURE you're tuning A440 or lower?
Do the necks(Michigan) warm up, get tuned to pitch, and then put in a case to get cold later? Tuning a bass with a warm neck & strings left to get cold will go sharp(i.e. string tension gets higher).
Are you tightening the truss rod while the strings have tension?

Nothing else hits me as possbily obvious since it is across brands except SX.
I'd discount humidity unless it's to the point of causing condesation on instruments and rust on them(or a damp basement with no dehumidifier) because the guitars aren't getting hit. We gig a LOT outdoors and I've not had this problem but am very familiar with temperature affecting tuning in realtime. At home(indoors) we keep humidity between 45 and 50%.
 
#3
Craig_S said:
It's a humidity issue, River Rat. ;) Get them out of the basement.

EDIT: The SX has a maple neck, doesn't it? The others are rosewood.
Click to expand...

All my guitars are in my bedroom in the same spot. No basement here. The SX and Yamaha are maple/rosewood and the Squier is all maple.

Johnny Crab said:
Do they have similar strings & tension as the SX?
Are you SURE you're tuning A440 or lower?
Do the necks(Michigan) warm up, get tuned to pitch, and then put in a case to get cold later? Tuning a bass with a warm neck & strings left to get cold will go sharp(i.e. string tension gets higher).
Click to expand...

My SX is actually using a higher gauge strings than the others. It has high gauge Webstrings (.110). My Yamaha has a medium set of Webstrings, and the Squier has Rotosound 99's. I'm sure I'm tuning them right and, as a lowly bedroom musician, they never leave the house.
 
#5
The problem is probably LACK of humidity, not too much of it. Basses, especially those with rosewood boards, will do this in dry climates. What happens is simple: the board dries out and shrinks, lengthwise. This increases relief, which you must then fight with the trussrod. I suggest you try a room humidifier. With 30-40% humidity, you'll see the necks flatten back out to the point where you'll need to loosen the rods again in a few days.
 
#6
dmusic148 said:
The problem is probably LACK of humidity, not too much of it. Basses, especially those with rosewood boards, will do this in dry climates. What happens is simple: the board dries out and shrinks, lengthwise. This increases relief, which you must then fight with the trussrod. I suggest you try a room humidifier. With 30-40% humidity, you'll see the necks flatten back out to the point where you'll need to loosen the rods again in a few days.
Click to expand...

I never really thought of that. We have a humidifier on our furnace, but I don't know how it's set. (Still living at home I don't get a say in that sort of thing) I can try a room humidifier and see if that helps any.

Craig_S said:
When did Squier make a maple neck jazz?
Click to expand...

It's a VM jazz.
 
#9
+1 for the lack of humidity. If your place is anything like mine, your furnace runs like every 25 to 30 min when it's cold out. Get yourself a steam humidifier, even a small one for your room where you store your instruments, and keep it running 24/7. I just got one a few weeks ago and placed it near the furnace intake so the steam gets pulled into the furnace when it kicks on and distributes the humidity throughout the house. I didn't think this would work as well as it does, but it does work. My family is more comfortable, the house feels warmer, and the necks on my basses flattened back out without tools or tinkering.
 
#10
levis76 said:
+1 for the lack of humidity. If your place is anything like mine, your furnace runs like every 25 to 30 min when it's cold out.
Click to expand...

The way my family sets it it's rare when it ever goes off. I think right now it's set at almost 70 degrees and I had to actually physically block the vent in my room so I don't die of heat stroke (our crappy house was built so that my room gets almost all of the AC/furnace air). If the air is really dry I can see how that'd affect my basses. I still wonder how half of my collection is completely unaffected however...
 
#12
sometimes you get lucky. graphite reinf rods increase your luck. i live on coast of
the pacific northwest---damp 9 months a year. had a 60's classic jazz with the same
problem. its more the instrument than the weather IMO.

i got rid of the bass. sad, i really liked that bass a lot. all my other basses
are fine in this weather.
 
#14
How is the grain oriented in the necks that are bowing?

I ask because my MIM reissue Jazz has had adjustment issues and one thing I notice is that its neck is almost perfectly flat-sawn. That means its "laminations" are stacked (versus side by side as in a quarter-sawn piece), which provides the least natural resistance to bowing.

http://www.edroman.com/techarticles/quartersawn.htm

Kind of a shot in the dark, but it would be interesting if your one straight neck was quarter sawn and the rest flat sawn.
 
#15
Falkner said:
I guess I'm not. :p

Would a thicker necked bass (like a P bass) be better at staying straight? It'd give me an excuse to buy that CV P-bass I've had an eye on for a while.
Click to expand...
Maybe, maybe not. I have an '08 USA Std. P bass with a rosewood board that becomes banana-shaped the moment the leaves begin to fall. I drag out the himidifier and voila, fixed. Naturally my graphite necked p bass doesn't have this problem.
 
#18
my basses are in my basement and my basement is very dry. typically, in the winter, the humidity is in the low 20s, you really want that number up somewhere around 40%-45%. I use 2 Bionaire humidifiers to get it done and it works great. I usually have to fill the water jugs once a day, but it beats fighting with a truss rod on a constant basis!

something like this Invalid Link Removed
 
#20
Falkner said:
The way my family sets it it's rare when it ever goes off. I think right now it's set at almost 70 degrees and I had to actually physically block the vent in my room so I don't die of heat stroke (our crappy house was built so that my room gets almost all of the AC/furnace air). If the air is really dry I can see how that'd affect my basses. I still wonder how half of my collection is completely unaffected however...
Click to expand...
It's Winter in Michigan. A room Humidifier will not help much. Cold & dry is a fact of life where you live.

I live in Massachusetts & if I want low action I have to set up the bass as the weather changes. As the Seasons change, fret buzz sometimes means raise the action instead of adjusting relief because I know the weather will change the next week.

We're talking 3 or 4 tweaks of 1/8th turn, adjust the bridge height & tune to pitch. With a little practice you can learn to do this with the bass hanging from it's strap, on your shoulder. You can even make a setup kit to go into your gig bag.

I saw the OP about your rods being maxed out. You may have to set up with some relief, go to a lighter gauge string or move to Hawaii. 8-)
 

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