Neck deflecting forward?

[Adrian Cho]

I am wondering if my neck is being flexed forward and if so, whether it's a sign of worse things to come or something I shouldn't worry about. Of course there is tension from the strings but shouldn't the neck be rigid enough to avoid being pulled forward?

Here's what I did:

I took a straightedge and put it along the side of the neck - specifically along the seam between the fingerboard and the neck with the straightedge on the wood portion of the neck (so that the fingerboard is showing above it). What I noticed is that the joint is straight but about 10 cm from where the neck butts into the pegbox, the seam delineates a curve up (towards the front of the bass) such that where the neck butts into the pegbox, the seam is about 1.5 mm from the straightedge. Now the fingerboard is dead straight (and was dressed about eight months ago) so this means that the fingerboard is about 1.5 mm thinner at the top.

I hope my explanation makes some kind of sense. I'm wondering if this is normal and if not, whether it could get worse. 1.5 mm doesn't seem a lot to be worried about.

Adrian

[arnoldschnitzer]

The neck/fingerboard joint should be straight. Causes of curvature as you have described: Loose joint near the nut end; weak or thin neck; weak or thin fingerboard; warpage resulting from unseasoned wood being used in the neck. A tiny bit of curvature is OK, but I would have it looked at. My bet is that the joint is loose.

[Pete OLeary]

Originally posted by adrian_cho
Of course there is tension from the strings but shouldn't the neck be rigid enough to avoid being pulled forward?

Nothing is perfectly rigid. Anything will deflect under stress. The question is how much?
And how stable is it?

the seam is about 1.5 mm from the straightedge.

That seems like too much. It's possible the joint has seperated as Arnold states.
That joint starts out ideally as very straight and flat. It is also possible that after some time the neck and fingerboard have warped 1.5mm under string tension and settled, so your luthier left the joint alone and dressed the fingerboard.
Have you had to adjust your bridge much?
Have you had the strings off and looked at the joint?

[Adrian Cho]

The joint SEEMS to be intact even along the part where the joint starts curving.

Let's say in theory that the joint is intact and the neck itself has warped a bit, can it be fixed and how?

Adrian

[Pete OLeary]

Originally posted by adrian_cho
The joint SEEMS to be intact even along the part where the joint starts curving.

Let's say in theory that the joint is intact and the neck itself has warped a bit, can it be fixed and how?

Yes it can. How? Read on.
The questions you might ask youself is, why?
Why is it bowed, and why change it.

The reason I asked whether you've had to adjust your bridge much is that it might indicate whether the joint is stable. If it is not stable, it will need attention sooner than later, and will cause playability problems or even further structural problems.
If the bass sounds good, plays good, and doesn't seem to require inordinate adjustment of the bridge to maintain consistent string height, I would leave it alone.
If the neck/fingerboard assembly unit seems to be flexing and not giving consistent action, *and* the joint is solid, then the neck and/or fingerboard may be too thin, as the Schnitzinator indicated.
It may be beefed up using various methods including a thicker fingerboard, a shim under the fingerboard, or even a truss rod as Mssr. Knickeloid has done (I believe?). Chime in if I'm mistaken here, Nick.
I've removed fingerboards and found that fungus attacked the maple beneath it, weakening the neck.
This required digging out the punky wood, treatment with some nasty chemicals, filling the area with epoxy, then cementing a maple shim on top of the repair.

[Adrian Cho]

I don't believe I have to adjust my bridge inordinately. I mean I do adjust my bridge every couple of months but I live in an environment where the humidity can vary greatly and I have changed the bridge height in recent times to change the feel/output/whatever of the bass.

My fingerboard is between 10 - 11 mm thick on the E side (measured somewhere up near the nut) and seems to be pretty much consistently that thickness to the bottom. From another thread I saw on here, that seemed to be about right however one luthier I spoke did think it was a little too thin (we were talking in the context of putting an extension on the bass).

I guess one thing to do if I don't get it looked at is to keep an eye on it and continue to measure it and see if it gets any worse.

Adrian

[Pete OLeary]

Originally posted by adrian_cho
I guess one thing to do if I don't get it looked at is to keep an eye on it and continue to measure it and see if it gets any worse.

There ya go.
Who did your fingerboard a while back? If it were M. Sonksen or or M. Hogan, I can positively state that they would have advised you of any impending issues.

[nicklloyd]

Pete, I think the van fumes are getting to you. Did A.Cho go to Chicago? Ottawa is a little far for M. Hogan or M.Sonksen to be making a house call (eh).

But as you stated, I do install composite graphite bars in my basses, old warped necks, as well as neck repairs. They add no noticeable weight, they are VERY stiff, easy to install, affordable, and Strad would've used them.

[Adrian Cho]

FYI, I have been discussing the issue of my apparently warped neck with Bill Merchant and he believes I should fix it and if I don't that it will get worse. I'm tending to agree.

Adrian