Double Bass Finger board relief

[Stuart.C]

Hi, I always had a suspicion my action was a bit high, based on other basses I tried. But after searching the forums I found string height of 6mm G, 10mm E at the end of the finger board is not really high.
But then I moved the ruler up the finger board and found that at the G harmonic the height was the same (maybe a touch more). At the D on the G string the height has only decreased to ~5.5mm ?

Is this normal? can someone give me an example of height of the G string at end of finger board, then at the G harmonic then at D.

I feel like there is a little relief in the finger board from the neck to the end and if I push it down my heights would be closer to 8mm G, 12mm E. I have low tension strings on now.

Thanks for your help.

 

[neilG]

Are you measuring the height of the string at the octave or the relief (camber)? To measure the relief you'd have to lay a long ruler from the nut to the end of the fingerboard. Or, press the string down at the end of the board to measure it.

 

[robobass]

Are you measuring the height of the string at the octave or the relief (camber)? To measure the relief you'd have to lay a long ruler from the nut to the end of the fingerboard. Or, press the string down at the end of the board to measure it.

Yes. If you don't have a long enough straight edge, have a friend press a string down at both the nut and the end of the FB, and look at the scoop. See if it's even, and note where it is the deepest. Then see how many business cards you can fit. Report back and one of the pros here will give you a prognosis.

Also, I'm not sure what you mean here:
"I feel like there is a little relief in the finger board from the neck to the end and if I push it down my heights would be closer to 8mm G, 12mm E."

 

[Stuart.C]

I am measuring at the G octave, then again at the D harmonic on the G string.
I suspect the height should have tapered more by the D harmonic?

I have 6mm at fingerboard end and 5.5mm at D harmonic, I am wondering if this is normal?

Also, I'm not sure what you mean here:
"I feel like there is a little relief in the finger board from the neck to the end and if I push it down my heights would be closer to 8mm G, 12mm E."

I have not tried a straight edge, but visually it looks like after the finger board leaves the neck it bows up very slightly. And the explains why the string height changes very little. If I push the finger board to what looks straight my heights at the end would be closer 8mm G, 12mm.
This would explain why I feel high action but measure normal action.

I will try to check the relief tonight, but I am hoping someone can tell me the measurements they get at the fingerboard and then at the D harmonic.

Thanks

 

[DoubleMIDI]

Hey Stuart.C,

Your way of measuring is not the way of measuring luthiers and private bass repair persons do. So even you explained how you measured it, nobody might answer with data, because it's not the way the do it.

I'm not finished with my first neck camber, but comparing the camber to my other basses, I think the lowest position measured with the string pressed down at both ends of the fingerboard is around the fifth (neck heel), maybe a little bit higher. (Please correct me if I'm wrong...)
So your measurements are not so unusual, I think.

The reason why this is done is the string to fingerboard angle. For high notes down the fingerboard the angle is rather high, so no risk of a buzzing string. But for fingered notes up the neck the angle without camber is much lower. So the camber helps this long vibrating string notes to avoid buzzing.
Depending on the string type, wide or narrow vibration, like in gut or steel) the camber needs to be deeper or less. But even for steel strings a little camber is needed.
A deep camber may need a higher action to avoid buzzing in the region of the fourth up to the octave, but if you don't get any buzzing the just lower the action.

Measure the camber the way Robobass told you, then then the experts here can tell you if it is deep or average, at the correct position or not.
Of course the easiest and most secure way is to have a luthier check your instrument.

BTW, bass guitars have a truss rod to control the amount of neck bending, but that doesn't work with (most) double basses, since they have a much more rigid neck than a bass guitar.

 

[Stuart.C]

Thanks

I just figured out it's called scoop or camber, not relief like on BG. I did measure by pushing down the string and the deepest is around 2.5mm.
I think this is normal, and the bass was setup originally for classical, but I have been doing mostly pizz these days and just starting to notice the smaller details I never noticed before.

 

[Jake deVilliers]

Thanks

I just figured out it's called scoop or camber, not relief like on BG. I did measure by pushing down the string and the deepest is around 2.5mm.
I think this is normal, and the bass was setup originally for classical, but I have been doing mostly pizz these days and just starting to notice the smaller details I never noticed before.

Stuart, if you use the 'Search' function you'll find many posts on this topic with data and opinion, both!