Double Bass Neck curvature

[Fleo]

Hi,
I'm trying to improve the playability in thumbposition. Assuming it had overstand and angle, I wonder if the curvature of the neck, not the fingerboard, has influenced recent flattening job and reduced the angle of the board in thumb position. So my question is this curve normal or does it point out a weak neck?

 

[DoubleMIDI]

Not that I have any knowledge...
... but that looks like a deformed neck.

As far as I know the neck should be straight and the fingerboard gets the length curvature by removing wood from it at the right places.

 

[jsf729]

Are you setting the straight edge on the fingerboard or where the neck meets the fingerboard?

 

[nogbert]

interesting to note that the back of the neck is not curved similarly.

 

[unbrokenchain]

Likely a thin fingerboard rather than a problem with the maple of the neck. Can't see the board because of your straight edge, but if the nut is any indication, it looks pretty thin. Is your string height rough in the middle of the board, but low in tp?

I had a Kay with a super thin board, and if I played a stopped note, say D on the G string, and played the open D at the same time, I would hear the open note raise in pitch when I let off the stopped note with the left hand. It was flexing like a bow.. fingerboard shim and carbon fiber inserts fixed that one. But a nice thick new board would have also worked I'm sure.

 

[Fleo]

Are you setting the straight edge on the fingerboard or where the neck meets the fingerboard?

Where the neck meets the board

 

[Fleo]

#1
Likely a thin fingerboard rather than a problem with the maple of the neck. Can't see the board because of your straight edge, but if the nut is any indication, it looks pretty thin. Is your string height rough in the middle of the board, but low in tp

#2
It was flexing like a bow.. fingerboard shim and carbon fiber inserts fixed that one. But a nice thick new board would have also worked I'm sure.

#1 That's exactly the case.
#2 Gonna propose this tot my Luther.

Thanks

 

[Fran Diaz]

It seems to me that your neck and fingerboard have bent over time. That should be a straight joint.
On the other side, the back of the neck looks rather flat. Was it maybe to compensate the deformation?
In my opinion you should bring the bass to a luthier so he can take measurements and give you options.

 

[David Potts]

Are you close to a specialist bass luthier? It looks as though the neck is doing a "banana" and you can also check for this by sighting down the glue line between the fingerboard and the neck (stand behind the bass and then step back until you can look past the scroll and nut). Check to make sure that the neck is not becoming unglued from the board - it does happen. If you love the bass perhaps go to the extent of having a carbon fibre rod set into the neck and a new fingerboard by a luthier.

 

[Fran Diaz]

It seems to me that your neck and fingerboard have bent over time. That should be a straight joint.
On the other side, the back of the neck looks rather flat. Was it maybe to compensate the deformation?
In my opinion you should bring the bass to a luthier so he can take measurements and give you options.

I can't edit my post.

I meant: "the back of the neck looks rather flat. Was it maybe shaved/reshaped to compensate the deformation?"

 

[Fleo]

Are you close to a specialist bass luthier? It looks as though the neck is doing a "banana" and you can also check for this by sighting down the glue line between the fingerboard and the neck (stand behind the bass and then step back until you can look past the scroll and nut). Check to make sure that the neck is not becoming unglued from the board - it does happen. If you love the bass perhaps go to the extent of having a carbon fibre rod set into the neck and a new fingerboard by a luthier.

Thanks David,

The bass is lovely and also needs a top repair cause it's sunken. Does a carbon rod influence the sound?

 

[Fleo]

I can't edit my post.

I meant: "the back of the neck looks rather flat. Was it maybe shaved/reshaped to compensate the deformation?"

It's built in 1960 and I'm the second owner,but the selling luthier didn't mention anything about the neck other than it needed a new fingerboard soon. After that I had the fingerboard replaned once, hence I discovered the bending.

 

[unbrokenchain]

the selling luthier didn't mention anything about the neck other than it needed a new fingerboard soon.

Selling luthier was correct
Most of the strength of the neck actually comes from the fingerboard thickness, plus having its grain oriented perpendicular to the neck, and the accompanying glue joint. Carbon fiber in the neck does help and isn't difficult to do, but not necessary if there's plenty of thickness in the fingerboard itself. The neck without a fingerboard is like a wet noodle, it will flex even under the weight of the scroll.

 

[Jake deVilliers]

Its a product of using the fingerboard as a stressed member of the assembly - wood comes in different stiffnesses and some combinations just can't deal with the tension of steel strings.

The way to really fix that is to remove the board, straighten the neck and install a 1/4" x 1/2" x 18" carbon fibre bar. Then you can re-install the original board and plane it straight with no concerns. Straight forever.

 

[CDickinson]

Or use a carbon fiber fingerboard. Moses graphite made one for my '60 Kay, looks like ebony and is preshaped and sized. Installing it is the next step in the rebuild I'm doing.

 

[M0ses]

Or use a carbon fiber fingerboard. Moses graphite made one for my '60 Kay, looks like ebony and is preshaped and sized. Installing it is the next step in the rebuild I'm doing.

I have one of these for electric bass. Very nice, very stiff, but it's made of solid graphite, not fiber + epoxy. Two different types of carbon

 

[David Potts]

May I pick up on a couple of things here IMO?

Most of the strength of the neck actually comes from the fingerboard thickness, plus having its grain oriented perpendicular to the neck, and the accompanying glue joint.

The fingerboard grain is parallel to the neck grain. In cheap ebony boards, when it is often not in patches, then it is very hard to plane without tearing out wood.

Then you can re-install the original board and plane it straight with no concerns. Straight forever.

The original board may or may not have straightened itself after its removal. Its gluing surface (back) must be flattened before reinstalling and the front of the board may have to be re-shot afterwards.

 

[robobass]

"the back of the neck looks rather flat. Was it maybe shaved/reshaped to compensate the deformation?"

That seems likely. My local guy would have removed the board and re-glued it with the neck held straight or bowed slightly the other way, and then glued it back on before doing any dressing or re-shaping of the neck. I wonder what the neck would do if you removed the board and left it for awhile? Anyway, if the scoop is in order the way it is, then I wouldn't lose sleep over it.