PDA

View Full Version : fingerboard lengths



Barry Sholder
07-30-2010, 09:40 AM
I am in the planning stages of building a gourd uke. I build gourd banjos and I am going to make the uke the same way only smaller but I need to know the actual dimensions of a concert neck and the scale for that as well. I found a place that sells preslotted neck ready for frets. It says 12x1 3/4x 1/4". with a 17.? scale. Is this a cencert board?

Swampy Steve
07-30-2010, 09:53 AM
17 tenor
Steve

Dusepo
07-30-2010, 10:03 AM
A tenor scale is 43cm (17 inches) and a concert scale is 38cm (15 inches).

For calculating fretboards, the free Stew-Mac thingy works wonders: http://www.stewmac.com/fretcalc.html

fahrner
07-30-2010, 01:10 PM
I am in the planning stages of building a gourd uke. I build gourd banjos and I am going to make the uke the same way only smaller but I need to know the actual dimensions of a concert neck and the scale for that as well. I found a place that sells preslotted neck ready for frets. It says 12x1 3/4x 1/4". with a 17.? scale. Is this a cencert board?
Sounds like what you found was a pre-slotted fret board for 17" scale, not a neck.

So, not a neck and not a concert scale.
Mainland sells both neck and fingerboard. Here's the link.
http://shop.mainlandukuleles.com/category.sc?categoryId=8

camface
07-30-2010, 08:56 PM
I've just taken a 17" scale template and started at the second fret to slot my concert scale fretboards. So, the what would be the second fret on a 17" scale becomes where the nut hits the end of the fretboard. So if you choose to buy a pre-slotted 17" scale fretboard, you can just cut it off at the second fret.

erich@muttcrew.net
07-31-2010, 02:39 AM
I've just taken a 17" scale template and started at the second fret to slot my concert scale fretboards. So, the what would be the second fret on a 17" scale becomes where the nut hits the end of the fretboard. So if you choose to buy a pre-slotted 17" scale fretboard, you can just cut it off at the second fret.

Good point. We did the same thing once with a soprano fretboard that was too long for the tiny sopranino we were making - you do lose the two frets at the other end, so for example a 14-fret fretboard then only has 12. In our case it didn't matter, but you should keep it in mind. Especially a banjo player might miss the extra frets.

Barry Sholder
07-31-2010, 06:10 AM
I have seen that and their necks will not fit a gourd because you have to shape the heel to the gourd and they don't have enough meat. I can build the neck just need fretboards. I may take the plunge and go to stwerat macdonlad and get fretting stuff and do it myself.

Allen
07-31-2010, 11:02 PM
You should be aware that cutting a fret board designed for a different scale length as suggested may get you in the ball park so to speak with the fret spacing, it is not going to be spot on. It's a simple check of the fret to fret spacing on each of the scale lengths that will tell you how far out they are going to be. Really depends on how fussy you are about those sort of things.

erich@muttcrew.net
08-01-2010, 01:53 AM
You should be aware that cutting a fret board designed for a different scale length as suggested may get you in the ball park so to speak with the fret spacing, it is not going to be spot on. It's a simple check of the fret to fret spacing on each of the scale lengths that will tell you how far out they are going to be. Really depends on how fussy you are about those sort of things.

Allen, I don't think that is quite right - neither from a mathematical nor from a phisical point of view. If what you mean is that you end up with a scale length of 374 point something instead of 380, then that is certainly true.

Here is a little test to check whether it works: You go to the stewmac fret calculator (http://www.stewmac.com/fretcalc/) and set up a tenor ukulele fretboard with a scale length of 420 mm and 14 frets. The measurements you get look like this:

420 mm fret scale
fret -- from nut ------ fret to fret
01 -- 23.573 mm --- 23.573 mm (nut-1)
02 -- 45.823 mm --- 22.250 mm (1-2)
03 -- 66.824 mm --- 21.001 mm (2-3)
04 -- 86.646 mm --- 19.822 mm (3-4)
05 -- 105.356 mm -- 18.710 mm (4-5)
06 -- 123.015 mm -- 17.659 mm (5-6)
07 -- 139.684 mm -- 16.669 mm (6-7)
08 -- 155.417 mm -- 15.733 mm (7-8)
09 -- 170.267 mm -- 14.850 mm (8-9)
10 -- 184.283 mm -- 14.016 mm (9-10)
11 -- 197.513 mm -- 13.230 mm (10-11)
12 -- 210.000 mm -- 12.487 mm (11-12)
13 -- 221.786 mm -- 11.786 mm (12-13)
14 -- 232.911 mm -- 11.125 mm (13-14)

OK, now you subtract the value up to the second fret to get the resulting scale length if you sawed the fretboard off there:

420 mm - 45.823 mm = 374.177 mm

OK, now you set up a new fret calculation with 374.177 mm as the scale length and 12 frets, and it looks like this:

374,177 mm fret scale
fret -- from nut ------ fret to fret
01 -- 21.001 mm --- 21.001 mm (nut-1)
02 -- 40.823 mm --- 19.822 mm (1-2)
03 -- 59.533 mm --- 18.710 mm (2-3)
04 -- 77.193 mm --- 17.660 mm (3-4)
05 -- 93.861 mm --- 16.668 mm (4-5)
06 -- 109.594 mm -- 15.733 mm (5-6)
07 -- 124.444 mm -- 14.850 mm (6-7)
08 -- 138.460 mm -- 14.016 mm (7-8)
09 -- 151.690 mm -- 13.230 mm (8-9)
10 -- 164.177 mm -- 12.487 mm (9-10)
11 -- 175.964 mm -- 11.787 mm (10-11)
12 -- 187.088 mm -- 11.124 mm (11-12)

The only differences in the fret-to-fret measurements are by one thousandth of a millimeter, which you definitely will never hear. The touch of your finger on the string will make much more difference than that.

There is a certain challenge involved that has to do with one of the oddities of ukulele tunings: With our truncated fretboard we are "capo-ing" up two frets but our scale stays the same, it doesn't go from C up to D tuning. In order to get back down to C tuning we have to reduce the tension on the strings and possibly also the string guages, both of which can affect the sound, the intonation, etc.

But... if the fretboard is "spot on" to begin with, then it really doesn't matter whether I play in open position, or fifth, or ninth... An A is always an A and a whole note is always a whole note.

Keep rockin' :music:
Erich

Moore Bettah Ukuleles
08-01-2010, 07:51 AM
I agree Erich. My fret slotting template is a Fender 25.5" guitar template from which I can get any scale length I want, from a baritone to a soprano, depending upon where you start.

DaveVisi
08-01-2010, 08:26 AM
You just have to remember which end to cut.

camface
08-01-2010, 08:45 AM
I didn't even shell out the $40 or so for the legitimate template. I just got LMII to slot a 17", 19 fret fretboard for me and I use that as my guide. I ground down a piece of brass rod I had on hand and it slips into the slots perfectly. I've never put more than 15 frets on a soprano or concert though.

Dave Higham
08-02-2010, 01:00 AM
Erich and Chuck are perfectly correct in what they say and do. But I think what Allen meant is that if Chuck is using a 25 1/2" template for all his instruments, instead of the 'standard' scale lengths of 13 5/8", 14 3/4" and 17" the nearest he can get will be 13.51" (a bit short), 15.16" (a bit long) and 17.02" (almost spot on). I haven't included the baritone, not wanting to offend Chuck's sensibilities.;)

Allen
08-02-2010, 02:34 AM
Unless I'm way off mark, and it's been known to happen then I'll try and explain my point.

What the question was and what I was referring to is that if you take a 17" scale fret board that has already had the fret slots cut, then cut off the first 2 frets to give you an approximation of the 15" scale length you do have more than just .001" variation.

In this example form StewMac fret calculator you are at .008" off on the first fret, .007" on the second, ,008" on the third, .008 on the fourth and so on. You also end up having a scale length of 15.14".

This has to be taken into account when setting out the bridge/saddle and any compensation.

Small variations, to be sure. But they all add up.

So the question is, would you be able to tell if intonation is out? If you set the bridge at 15" you surely will. If it's set up for 15.14" plus any compensation, then the answer would be no. Or at least it will be as good as it's going to get.

Will it work? Apparently does for some. Not arguing the fact. Just making a point that you should be aware of the differences, as I see way too often questions about intonation and how to go about fixing the problem. This is just one area that may give you issues.


15" fret scale

fret from nut fret to fret
1 0.842" 0.842" (nut-1)
2 1.637" 0.795" (1-2)
3 2.387" 0.750" (2-3)
4 3.094" 0.707" (3-4)
5 3.763" 0.669" (4-5)
6 4.393" 0.630" (5-6)
7 4.989" 0.596" (6-7)
8 5.551" 0.562" (7-8)
9 6.081" 0.530" (8-9)
10 6.582" 0.501" (9-10)
11 7.054" 0.472" (10-11)
12 7.500" 0.446" (11-12)
13 7.921" 0.421" (12-13)
14 8.318" 0.397" (13-14)
15 8.693" 0.375" (14-15)

17" fret scale Printable

fret from nut fret to fret
1 0.954" 0.954" (nut-1)
2 1.855" 0.901" (1-2)
3 2.705" 0.850" (2-3)
4 3.507" 0.802" (3-4)
5 4.264" 0.757" (4-5)
6 4.979" 0.715" (5-6)
7 5.654" 0.675" (6-7)
8 6.291" 0.637" (7-8)
9 6.892" 0.601" (8-9)
10 7.459" 0.567" (9-10)
11 7.995" 0.536" (10-11)
12 8.500" 0.505" (11-12)
13 8.977" 0.477" (12-13)
14 9.427" 0.450" (13-14)
15 9.852" 0.425" (14-15)

erich@muttcrew.net
08-02-2010, 07:45 AM
...In this example form StewMac fret calculator you are at .008" off on the first fret, .007" on the second, ,008" on the third, .008 on the fourth and so on. You also end up having a scale length of 15.14".

Your scale length is 15.14x" and the fret-to-fret measurements are exactly right for that scale length. You only get the differences of .008 / .007 if you try to make the scale length 15.000" instead - in that case you're off on every single fret and the differences do add up (to a total of 0.072" at the 12th fret).


...So the question is, would you be able to tell if intonation is out? If you set the bridge at 15" you surely will. If it's set up for 15.14" plus any compensation, then the answer would be no. Or at least it will be as good as it's going to get.

The intonation would be just as good on a 15.14x inch ukulele as it would on a 15.000 inch ukulele if you built it correctly. The point is simply that you cannot make a 15 incher out of a cut-off 17 inch fretboard...

What intrigues me is that the scale length of 15.14x inches seems to bother people, as if it were not quite right. But what if we compare the metric measurements: 15 inches would be 381 mm - but what people build in the metric system is normally 380 mm for a concert uke, not 381 mm. A lot of tenors in the metric system are built to 420 mm, but that's quite a ways off from 17 inches (= 431.800 mm) - the difference is almost half an inch! So obviously you can't put a 17" tenor fretboard on a tenor uke with 420 mm scale length, nor can you put a 420 mm tenor fretboard on a 17" tenor uke - either way, your intonation would be completely wrong.

Now granted, if you are building your instrument according to a plan or a kit or whatever and it is supposed to be a 15" scale and you try and make it work with a 15.14x" fretboard... Naw, you don't want to do that. But I thought the original poster was planning to make a gourd ukulele. AFAIK they haven't come up with the perfectly tempered pumpkin yet - although they may be working on it ;) I think you'll agree that a build like that probably wouldn't suffer all too much if you moved the bridge/saddle just a few millimeters further down.

Allen, I really hope you're not offended. I can be such a pain, I know. But my intentions really are good and I don't want to put anyone down. If you all want to tell me off, please PM me and I will really shut up - promise.

And the UU PITA Award goes to...... me.

Sorry, Erich

Dave Higham
08-02-2010, 08:04 AM
Erm.... I think we're all trying to say the same thing. :wallbash:

Moore Bettah Ukuleles
08-02-2010, 08:39 AM
It ain't rocket science, it's simple math. A scale length can be anything you want. For instance, my tenor scale length is 17.03" (433mm) with a 2mm compensation. I've seen other builders build tenors with up to a 17.5" scale. Who cares as long as everything else is relative to that scale? I don't really care about the scale length itself, what I care about is the consistency of the fret spacing and that the math is correct relative to everything else!
BTW, the reason I use a Stewmac fret template is that I have in my possesion a handful of "ukulele" fret templates, some that are sold by reputable outfits that should know better, and they are ALL, without exception, inconsistent. They are all off to varying degrees. You can do what you want with the rest of the build, but for me the most critical aspectt of the instrument is that the math must be correct. Music is mathematics in an audible form. I won't take chances with it.

Allen
08-02-2010, 11:01 AM
The scale length doesn't bother me one little bit. Just as Chuck has said, it's in the math.

It's just that I've seen this very same discussion pop up many times on Guitar forums and it confuses the heck out of new builders who simply do not take into consideration that they will need to modify the scale length/compensation factor to something slightly different to what they had in mind.

In my initial response I probably didn't explain my point any where near well enough. I knew what I was saying in my head though.

My point is that for experienced builders, most if not all will understand all this, but those just starting out probably don't.

Timbuck
08-02-2010, 11:46 AM
I don't understand any of this :confused:????..co's i've just finished off a bottle of "Chillian Chardonnay wine" so I'll read the post again in the morning and see what it's all about..Goodnight everyone:)

Timbuck
08-02-2010, 09:50 PM
Thats better! a good nights sleep:cool:..Now back to the thread..
Just like Chuck said..Get the frets in the right place and it won't sound out of tune...I make my own templates for my set up, I use a digital Vernier gauge to mark them out.

erich@muttcrew.net
08-03-2010, 03:09 AM
If you want to do the math yourself you can use the "rule of 18" - which is actually the rule of 17.817.


The distance to the next fret is equal to the remaining string length divided by 17.817.

So, from the nut to the first fret it is the scale length S divided by 17.817, for example

17" / 17.817 = 0.954" (nut to first fret)
15" / 17.817 = 0.842" (nut to first fret)
15.144" / 17.817 = 0.850" (nut to first fret)
433 mm / 17.817 = 24,303 mm (nut to first fret)
and so on


You then have to calculate the remaining string length by subtracting the nut-to-first value from the full scale length. Note that you can get some issues with rounding, so it's best to do the math with values that are not rounded too far (in Excel, for example, the values are acutally calculated to some long decimal value and just displayed with the selected number of decimal places).

Since the factor of 17.817 is constant, you can also calculate constants for each fret position as fractions of the total scale length by taking 1.000 as the open scale length (or 100.000 to get percent values) and determining the relative fret positions based on this rule. This is what you get:

nut -- 0.0000
1 ---- 0.0561
2 ---- 0.1091
3 ---- 0.1591
4 ---- 0.2063
5 ---- 0.2508
6 ---- 0.2929
7 ---- 0.3326
8 ---- 0.3700
9 ---- 0.4054
10 --- 0.4388
11 --- 0.4703
12 --- 0.5000
13 --- 0.5281
14 --- 0.5546
15 --- 0.5796
16 --- 0.6032
17 --- 0.6254
18 --- 0.6464
19 --- 0.6663
20 --- 0.6850
etc.

Now you can take your favorite scale length and by multiplying with these constants you can determine the nut-to-fret measurements for that scale. Enjoy! :cool:

EDIT: Check out the Tools, Formulae and Data (http://www.liutaiomottola.com/formulae.htm)section at liutaiomottola.com for lots more on the physics and mathematics of stringed instruments.

Timbuck
08-03-2010, 08:03 AM
I'm amazed ...can anyone actually mark and cut slots into a wooden fretboard..with an accuracy of 4 decimal places..1/10 of a thou: ... wow :):) :rolleyes:

Moore Bettah Ukuleles
08-03-2010, 08:09 AM
Not by hand you can't.

erich@muttcrew.net
08-03-2010, 09:42 AM
I sure can't - I'm glad if I get within one tenth of a mm. :) But the math works better if you do the calculations first and then round the results, not the other way around:

433 * 0,0561 = 24,2913 => 24,3
433 * 0,056 = 24,248 => 24,2 => off by a tenth

Believe me, it gets a lot worse if you round your factors even further...

Best to calculate first, then round, then mark, then check, then saw.