Truss rod needs continual adjustment - is this normal?

Jake of Bass · #1 01-06-2009, 03:14 PM

I've searched but can't seem to find much, if anything, about this issue I'm experiencing.

I recently (two months ago or so) had a setup on my EBMM Stingray. It came out really sweet as you'd expect, and I took it home and kept playing it.

A week or so later there was a slight increase in the bowing of the neck that made playing and tone differences quite noticeable (to me at least). So I adjusted the truss rod.

A week or so later, the same thing. Adjustment made.

A week or so later, the same thing. Adjustment made.

A fortnight or so later, the same thing. I think you can see where this is going.

My thing is here is why does it gradually keep bowing slightly. Shouldn't it just hold position once the adjustment has been made? The turns I make are small ones each time (maybe 1/8 turn) but even so with the amount of adjustments I have to make I'm worried I'll one day run out of turns and still need to keep adjusting it.

Any thoughts, and is this normal? I read that maple necks take a long time to settle in. My bass is currently about 3 1/2 years old. Cheers.

JustDavid · #2 01-06-2009, 03:25 PM

So far you've added 1/2 a turn? Has the frequency of adjustment decreased from 7 to 14 days?

I wonder if it's a seasonal adjustment of the neck to environment you are seeing. What's going on with your humidity & temperature inside & outside? Coating on the neck back & fingerboard?

It might be settling in after the setup. If a tension-changing string change wanted a truss rod change it might be recovering from that.

What strings? High, mid, low tension?

ThunderLizard · #3 01-06-2009, 03:34 PM

Jake-
My understanding.....
As you make your adjustment, the truss rod nut moves 'forward'. As the neck bows, the truss rod move 'back'. I don't think you'll run out of room.

Jake of Bass · #4 01-06-2009, 10:46 PM

Ok... maybe you could please explain how a truss rod works a little? My (limited) understanding is that if you keep turning it in one direction it will eventually run out of turns. Is this correct?

My bass is a five string and has Ernie Ball Regular Slinkys (45-130). The same strings were put back on after the setup (though I'm putting new ones on this afternoon, same type).

The frequency has neither increased nor decreased; it seems to need adjusting every week or two (give or take a few days) and I've added maybe 1/2-3/4 of a turn. How many turns are possible?

Even if someone can link me to some really comprehensive info, that would be much appreciated.

T-Bird · #5 01-07-2009, 03:19 AM

Hi.

Like JustDavid said, I'd vote for seasonal climate changes.

You might eventually run out of turns, but usually with other than dual action truss rods, there's a possibility to add a washer(s) between the neck and the nut and everything is great again.

Wood never really "settle in" as it's an organic material, allthough dead.

If the setup was done in a way that they completely released the tension on the truss rod, it might need constant tweaking for a relatively long period of time. Nothing wrong with it, it's just a way it is. For me anyway.
Most of the luthiers I know won't ship the instrument immediately after the completion, they like to observe the behaviour of the neck for a while.

Regards
Sam

Jake of Bass · #6 01-07-2009, 04:45 AM

Well where I am in Brisbane it is a sub tropical climate and it is summer here right now, so maybe that's why. I guess for me it's one of those instances where I don't know a lot about the truss rod and so I'm perhaps worrying more than necessary.

Just out of curiosity, how many turns does the average truss rod have in it? Or is that a bit like asking how long is a piece of string?

JustDavid · #7 01-07-2009, 07:01 PM

Folks, I'm certain the below is wrong in many ways. It's not intended to be right, just meant to transmit how I visualize neck relief factors. I invite corrections & constructive criticism.

My view of a truss rod is a bloody long bolt, anchored firm on one end, with the threaded end poking through a hole on the material with an accessible nut on that end.

This bolt/nut is on the bottom side of the neck, close to where your fretting thumb slides along.

It's on the bottom side of the neck to counteract the pull of the strings as they pull along the top of the neck.

When the strings pull more (like when you install a high-tension set) this pulls the neck front (fingerboard side) more. Tightening the nut counteracts this forward pull.

The wood acts in the same direction as the truss rod, like a second weak non-adjustable truss rod. But it's force changes depending on how much moisture it contains. It will get & give moisture from the air. Moisture in the air fluctuates seasonally; less when it's cold & more when it's hot.