Fingerboard radius?

[slapthefunky4]

I know that on electric basses, most of them have a constant radius along the entire length of the fretboard.

Do upright basses have a constant radius or does the radius get bigger as you get closer to the bridge?

I heard somewhere that uprights have a 6" radius fingerboard. I'm just trying to verify if this is true.

Thanks.

[Pentabass]

somewhere, sometime, this has been discussed. I don't remember the answer, but if you do a search, you will find more than you bargained for...

[robobass]

I think most good modern luthiers strive for a constant radius, which I prefer. You see a lot of basses with an increasing (or decreasing? I mean the radius gets smaller) radius as to go toward the nut. 6" sounds ballpark, but there are lots of variables.

[ctregan]

Since the width of the fingerboard changes, it seems like it would have to be a compound radius. If it is 6"r at the nut, Then would it be 8" or 9"r at the wider part?

[1st Bass]

Why would the width change the radius? If I slice a chunk of pipe, so that it is 1" wide at one end, and two at the other, the radius has not been altered at all-- I just have a wider slice of the same pipe.

On the other hand, many instruments (violins at least) DO have a flatter (bigger) radius at the small end. I happen to keep my violin FB radius at 42 mm from end to end. It gives an illusion, however, of changing from one end to the other.

[vejesse]

Fretting guitar necks gives you some insight into the difference between a straight radius and a compound one. If you're going to maintain a true straight radius all the way down you have to plane or sand 'on air' for a portion of the fingerboard. This is no mean feat on a bass fingerboard because it's so long and the fingerboard relief is deeper. I've done some experimenting with different radius schemes - including plotting out the fingerboard surface with a CAD program and what I've stuck with is simply planing and sanding along the lie of the strings. Maybe adding some cross hatch type sanding strokes to help eliminate flats left from the plane.

[Jake deVilliers]

This discussion got me to check the three new boards I have in stock with my profile gauge, looking for some hard data. They are brand new high quality ebony from a trusted supplier and they are definitely different end to end.

All three have about a 4" radius at the nut and about a 6" radius at the bridge end.

[ctregan]

Thanks Jake, I assumed it was some kind of cone shape but never actually knew for sure. Violins do have a constant radius of 42 mm from end to end as stated by 1st Bass. A constant radius would be much easier to fit!

Jake, is the radius offset from the center of the board to match the bridge shape? Is it offset at the nut also?

[Jake deVilliers]

The round boards are even, the bevelled board is non-concentric ie thickest near the A string.

And I think the bridge is offset to match the fingerboard and the string heights.

[kurt ratering]

"If I slice a chunk of pipe, so that it is 1" wide at one end, and two at the other, the radius has not been altered at all-- I just have a wider slice of the same pipe".-1st bass



a pipe doesnt have "relief "or "scoop" though. will this change the radius?

also, i am not a player so please tell me if this is accurate. from a players perspective would it be more comfortable to have the fb flatter at the nut end? ...less elbow/wrist work to finger all strings?

[ctregan]

The scoop should not change the radius, it is the same outside profile only deeper.

The fingerboard at the nut seems flatter because the width is very narrow. Less overall rise compared to the bridge end.

[Jake deVilliers]

Originally Posted by kurt ratering

from a players perspective would it be more comfortable to have the fb flatter at the nut end? ...less elbow/wrist work to finger all strings?

Nope, the opposite. I really don't see how you could use the bow to play one string at a time with a flat fingerboard.

It is much easier to play a smaller radius than a flat board, even on a guitar - with the string tension on a DB it would be nearly impossible.

[Nagrom]

If radii describes the distance from the center of an arc or circle to the perimeter, then moving the perimeter closer to the center will indeed change the radius. By the amount of the removed material.

[Jake deVilliers]

Originally Posted by Nagrom

If radii describes the distance from the center of an arc or circle to the perimeter, then moving the perimeter closer to the center will indeed change the radius. By the amount of the removed material.

Not necessarily. I'm not much of a theoretician but I think that if you put some scoop in the middle of the board you move the centre of the radius rather than altering the radius ie the denty part has the same radius but from a point further from the surface.

I think that's what ct was talking about. Am I making sense here guys?

[kurt ratering]

hey jake, im not talking about a dead flat fb, just flatter on the nut end to make reaching over to your "e" string a little easier. as for bowing a flat fb, its the arch of the bridge that would determine that.

[Jake deVilliers]

Reaching over to the E isn't easier with a flatter board. Try playing an early Martin with a wide 16" R board and an early Tele with a 7.25" R board and report back.

[kurt ratering]

point taken, was just askin'

[Jake deVilliers]

Hey Kurt, I see that you are advertising "Johnson String Instrument, New England's largest and most complete violin shop etc" - is that where you work? What instrument do you play? If you played violin it would make a much less expensive experiment!

Hey I just checked your 'Gear List' - nicely done!

[kurt ratering]

yup, not in the fiddle shop though, strum a litlle guitar, but by no means a musician.
why, is this thread going to turn on me?

[Nagrom]

If you draw an arc with a radius of 150mm, then scoop the centre by 1mm, you now have an arc with a radius of 151mm, and a relocated centre point that has moved 1mm farther away from its previous position. So sayeth the AutoCAD.