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Using a 26 3/16" scale fretboard on a 25 1/2" scale 18" neck

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Feb 17, 2020 - 10:53:01 PM
37 posts since 1/26/2020

Hello all,

I'm attempting to get an early 1890s lower level AC Fairbanks "Fairbanks and Cole" wavy logo banjo, back up and running. The ones with the thin spunover pot and the slotted screws. It has an 18" neck with a 25 1/2" scale based on where it appears the bridge used to be. There was an attempt to remove the fret board at some point in it's life, so there wasn't much left to go by, in terms of finding the 12th fret.
It had what was left of a crumbling 1/8" thick 2 layer fretboard before. The closest I could get to that thickness was a 3/16" pre-slotted board from Stewmac, which has a 26 3/16" scale.
What I'd like to know is how much will this affect the intonation or tuning, etc.? I'm likely not good enough to notice much.
I'm also contemplating using nylgut menstrel strings to achieve a lower plunky sound, and it seems if I have to push the bridge further back on the head it will make it sound not so plunky. If it's not to my liking I'll just go back to light tension Nylguts like I have on my SSS UF.

This is going to be my "give it a try" banjo, but I don't want to do something I can't reverse. Hopefully I haven't missed much information here.

Edited by - tbchappe on 02/18/2020 17:37:02

Feb 18, 2020 - 5:06:47 AM
Players Union Member

jduke

USA

1062 posts since 1/15/2009

On a pre-slotted fretboard, you can shorten the scale length of the banjo by cutting (shortening) it back to the first or second fret. Measure from the first fret, which becomes the new nut, to the new 12th fret and double that for your scale length. It will be shorter, but if it's not short enough, try from the second fret. Check by measuring before cutting. This will also help you see where the new bridge location will be, it will move.

Using a Gibson 26 3/16 scale shortened by one fret will result in approximately a 25 3/4 inch scale. Is that close enough?

Edited by - jduke on 02/18/2020 05:08:14

Feb 18, 2020 - 5:10:21 AM
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3809 posts since 5/12/2010

Using a longer scale fretboard than what the banjo was originally designed for will place the bridge further towards the tailpiece.

On most old banjos the tailpiece is already fairly close to the tailpiece so the fretboard you got from Stewmac may not work.

You can simply measure from the edge of the nut slot to find where the 26 3/16" scale will end up, but my guess is this board will not work.

You would probably be better off to measure from the nut to the place you want the bridge to be and order a pre-slotted board of that scale length.

I buy pre-slotted boards from LMII, but you have to profile the board to fit the neck being careful to align the center line with the path of the 3rd string.

Feb 18, 2020 - 5:15:57 AM

2799 posts since 2/18/2009

A 26-3/16 board with the first fret removed will be approximately 24-3/4". If you shorten the scale length too much you may possibly move the 5th fret too far toward the peghead, which would make the 5th string nut have no place to be installed. Stew-Mac has a free online fret position calculator, I would use that to figure out what will work for you given the neck and pot you have.
Zach

Feb 18, 2020 - 5:16:10 AM

3809 posts since 5/12/2010

Jeff's solution will also work, and has been done many times. I have done that myself, so don't know why I didn't think of that since you already have bought a board. Maybe the minor stroke I recently had is impacting my memory.

Feb 18, 2020 - 5:22:02 AM

3809 posts since 5/12/2010

Placement of the 5th string nut matters only if you are playing a style which requires fretting the fifth string, and approximating the original scale length would not cause much of an issue with this anyway.

Getting a board slotted to the actual scale the banjo was designed for would be the better solution if the banjo is to be used for a style where fretting the 5th is common. If it is to be used for "Old Time" styles such as "Clawhammer" it doesn't matter. I often place the 5th string peg at the 6th or even 7th fret on my short scale frailers to allow more room for 4th string slides.

Feb 18, 2020 - 5:23:30 AM

12723 posts since 6/29/2005

Here's what fingerboards of 25.5'" scale and 26 3/8" look like next to one another.  Cutting off the first fret is probably the easiest solution, and you'd only lose one fret.

Feb 18, 2020 - 5:38:32 AM
Players Union Member

rudy

USA

14988 posts since 3/27/2004

Going from a 25-1/2" scale length to a 26-3/16" won't change your intonation or tuning, that's simply a matter of bridge positioning.  One thing it WILL change that is pertinent to your needs is where the FIFTH fret will end up.

Since you don't know the exact scale length and all you have to go by is where it appears the old bridge was positioned that means you're going to need to figure out what scale length works best for what you have in hand. The number one concern I'd have is to establish the scale length that will result in the fifth fret lining up with the neck bump out.  You already have the neck (without the fret board...) and it could result in needing to modify the neck if you don't get the fifth fret location right.

Check a few photos of the same banjo that show the fifth fret position, measure from the nut location to where that same position would be on your banjo, and check the fret layout distances to match that up with the correct scale length would be for your instrument.  In your case it's probably best to not have to modify the neck if possible.

You probably know this, but changing from Nylgut Classics to Minstrels will mean tuning down to lower pitches.  It's not so much about feel (...or "plunky-ness"...) but what tuning you want to end up with.  If you want to play in standard tunings you need to stick with Nylgut Classics.  (Do watch your spelling of Minstrel...)  wink

Edited by - rudy on 02/18/2020 05:45:06

Feb 18, 2020 - 8:53:54 AM

rcc56

USA

2578 posts since 2/20/2016

To find the approximate original scale length, measure from the the estimated original position of the front of the nut to the estimated original position of the 5th fret. This will be approximately 1/4 of the scale length. The result will be perhaps 0.03" off, but since a banjo has a movable bridge, we can live with that.

If the Stew-mac board is unsuitable, I'm sure you can find someone to take it off your hands.

There are several suppliers who can slot a board to your specifications.

I would think that moving a bridge closer to the rim will tend to brighten the tone, while moving it closer to the center of the head will deepen it. A small change in position [1/8" or so] will probably not have a great effect on the tone.

Feb 18, 2020 - 10:40:15 AM

733 posts since 9/7/2005

Hey guys, I am way confused here. Some of you make instrument necks from scratch and I don’t so I may have some wires crossed so please de-confuse me.
If you already have a fretboard that is slotted for a 26.187 scale length, but plan on mounting it on a banjo with a 25.5 scale banjo, not only does the overall scale length change, but according to the fret calculator, the distance between each fret to fret dimension changes also depending on the scale length you choose. It may not be much, but it is a measurable distance and most of us are here to split the hairs that make a difference between pre war, post war, anti war, this war, that war, etc, etc, sound.
Just cutting off one fret does not change the distance between the remaining frets, nor does moving the bridge position all over the head.
So would not this proposal make the intonation off a bit at each fret position?
This make no difference playing a fret less banjo or on open strings, but as soon as you fret any string this comes into play. Fret two or three strings at once and each note will be off by just a smidge making the guy playing next to you think you are out of tune again. Please de-confuse me as I thought these little differences actually did matter.

Feb 18, 2020 - 11:49:33 AM

2902 posts since 5/29/2011

You can use a guitar fingerboard that has a 25 1/2" scale as easily as you can use a banjo fingerboard. Luthier's Mercantile can make a fingerboard any scale length you want and can sand it to proper thickness for you. Ebay has a number of sellers who sell guitar fingerboards and they are not all in China. Worth a try. It would be easier to use a guitar fingerboard and cut it to the right profile than use a banjo fingerboard which has the wrong scale for your instrument. Stewart MacDonald no longer sells a profiled banjo fingerboard so you are going to have to cut the profile anyway.

Feb 18, 2020 - 12:16:43 PM

6876 posts since 8/28/2013

quote:
Originally posted by Dogfeathers

Hey guys, I am way confused here. Some of you make instrument necks from scratch and I don’t so I may have some wires crossed so please de-confuse me.
If you already have a fretboard that is slotted for a 26.187 scale length, but plan on mounting it on a banjo with a 25.5 scale banjo, not only does the overall scale length change, but according to the fret calculator, the distance between each fret to fret dimension changes also depending on the scale length you choose. It may not be much, but it is a measurable distance and most of us are here to split the hairs that make a difference between pre war, post war, anti war, this war, that war, etc, etc, sound.
Just cutting off one fret does not change the distance between the remaining frets, nor does moving the bridge position all over the head.
So would not this proposal make the intonation off a bit at each fret position?
This make no difference playing a fret less banjo or on open strings, but as soon as you fret any string this comes into play. Fret two or three strings at once and each note will be off by just a smidge making the guy playing next to you think you are out of tune again. Please de-confuse me as I thought these little differences actually did matter.


The distances between frets will change with different scale lengths, but the ratios between the frets do not change.  It's the ratios that determine the note positions within a scale; as long as those are accurate and consistent, each note will sound correctly no matter the scale length.

Feb 18, 2020 - 1:29:51 PM
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2799 posts since 2/18/2009

quote:
Originally posted by Dogfeathers

Hey guys, I am way confused here. Some of you make instrument necks from scratch and I don’t so I may have some wires crossed so please de-confuse me.
If you already have a fretboard that is slotted for a 26.187 scale length, but plan on mounting it on a banjo with a 25.5 scale banjo, not only does the overall scale length change, but according to the fret calculator, the distance between each fret to fret dimension changes also depending on the scale length you choose. It may not be much, but it is a measurable distance and most of us are here to split the hairs that make a difference between pre war, post war, anti war, this war, that war, etc, etc, sound.
Just cutting off one fret does not change the distance between the remaining frets, nor does moving the bridge position all over the head.
So would not this proposal make the intonation off a bit at each fret position?
This make no difference playing a fret less banjo or on open strings, but as soon as you fret any string this comes into play. Fret two or three strings at once and each note will be off by just a smidge making the guy playing next to you think you are out of tune again. Please de-confuse me as I thought these little differences actually did matter.


Cutting off frets at the nut end can be thought of as being like installing a permanent capo. If you always had a capo on the first fret of your prewar banjo the scale length would be shorter and it would still play in tune.

Zach 

Feb 18, 2020 - 1:37:24 PM

733 posts since 9/7/2005

George, Thanks for the response , but I still remain confused. What you say I can believe playing a fretless banjo, but if you just arbitrarily move a bridge on a fretted banjo to a different scale length, the position of the frets stays the same, so these ratios you refer too are limited where they can move on the string length by the limitations of the position of the frets that were meant for a different scale length.
I.E. If you move the bridge a half inch either way from it’s correct position, the 12th fret harmonic will move to accommodate the new scale length —on the string—, but it will no longer be exactly over the 12th fret.

Pluck an open sting of any length and there will be a harmonic node at the half way point (12th fret) and the equivalent 5th, 7th and 9th fret. Those positions on the string will all change as the string length gets longer or shorter. If you fret the neck on a fixed position (or fret) of a given scale length and then shorten the scale length those nodes/harmonics will move accordingly along the string. The ratios you speak of will will act naturally on an open string, but as soon as you fret that sting it needs to mathematically match up with those nodes/harmonic positions to remain in tune.

Again I may be stressing minute differences that in the real world do not matter, after all I no longer have a teenagers hearing (working near F4’s in Vietnam took care of that) and the resultant ringing (and voices!) in my head make this hair splitting a moot point.
Sorry, I am still confused, but thanks George for trying, but so far I am still not convinced you can just shorten or lengthen a scale length on a fretted instrument just randomly, but still remain in tune on a fixed/fretted point that is not changing ratios at the same time the string length is changing.
Did I mention that my much older sister dropped me on my head frequently as a child to get me to “fit in” with the banjo crowd in latter life? Luckily my very thick head saved me!

Edited by - Dogfeathers on 02/18/2020 13:49:56

Feb 18, 2020 - 2:12:23 PM

733 posts since 9/7/2005

Zachary,
That is a good point and seems to be true to my ringing aged ears. But when I crunch the numbers as minute as they be, with the capo in place at the 1st fret moves the 12th fret harmonic to the13th fret and mathematically it moves the harmonic on the string only .019 which is only about 3 or 4 human hairs up the neck. I still can get a harmonic moving my fingers .100 either way of the 13th fret so a .019 difference is audibly imperceptible to me so I guess I am just chasing my own tail. If only I had teenage -dog ears-and stayed away from F4’s, this would be all cleared up.
I also forgot to mention that I worked as a prototype machinist for 35 years and in that world, a part that was off by a single hair was scrap...... I know,..... picky, picky, picky!

Feb 18, 2020 - 2:28:48 PM

rcc56

USA

2578 posts since 2/20/2016

Frets are laid out using the constant K=17.817.

Scale length [X] times [K] yields the first fret position [Y1]. [X - Y1] x K yields 2nd fret position [Y2]. [X - Y2] x K = 3rd fret position. And so on. It's a chain equation.

If you crunch the numbers, you'll see that it works out.

Feb 18, 2020 - 2:36:21 PM
Players Union Member

rudy

USA

14988 posts since 3/27/2004

Slapping a capo on at the first fret and not changing bridge position (which you shouldn't...) moves the harmonic up to the old 13th fret location, which now effectively becomes the octave.

There's nothing magic about "running the numbers"; it's all basic math and an understanding of how half step intervals are generated for a given scale length.

Feb 18, 2020 - 5:21:09 PM

37 posts since 1/26/2020

quote:
Originally posted by jduke

On a pre-slotted fretboard, you can shorten the scale length of the banjo by cutting (shortening) it back to the first or second fret. Measure from the first fret, which becomes the new nut, to the new 12th fret and double that for your scale length. It will be shorter, but if it's not short enough, try from the second fret. Check by measuring before cutting. This will also help you see where the new bridge location will be, it will move.

Using a Gibson 26 3/16 scale shortened by one fret will result in approximately a 25 3/4 inch scale. Is that close enough?


jduke, that was a prefect explanation. thank you kindly!

Feb 18, 2020 - 5:44:10 PM

37 posts since 1/26/2020

Thanks everyone. I'm finally getting to read these responses, as I work 3rd shift, so my hours are weird. Thanks for the correction on mentstrel, I'm usually pretty good about that stuff. I didn't realize the postion of the 5th string nut compared to the 5th fret was so important, though I play overhand so it shouldn't be that big of a deal, hopefully. I totally understand the position of the bridge based on whatever the 12th fret may become once the board is cut. and a 25 3/4 scale seems pretty close to what the original setup was.
Yes, I'd like to tune the banjo much lower after hearing a lot of people playing low tunes on youtube. I've read that the closer to the center of the heade the bridge can go, the lower the tone. It may not sound great on this old banjo, but I can always put normal nylgut strings back on if it doesn't sound good. This was a relief to read these responses, and get some reinforcement on all of the other threads i've been reading in this group. You folks are great.

Blaine

Feb 18, 2020 - 6:56:24 PM

2799 posts since 2/18/2009

25-3/4" is not what you will get if you remove the first fret. The first fret is slightly under 1.5 inches long, so you will get approximately 24-3/4"
Zach

Feb 18, 2020 - 7:11:04 PM

37 posts since 1/26/2020

Zachary, I just got done using a calculator site and got a similar measurement. My final scale was 24.895", which is fine with me. I'm wanting to push the bridge further in. This thread gave me a better understanding of how to manipulate the banjo. And it puts the 5th strong nut maybe 1/16th off of the 5th fret. I think I can compensate for that when sizing the main nut.

Edited by - tbchappe on 02/18/2020 19:11:32

Feb 19, 2020 - 9:15:37 AM

6876 posts since 8/28/2013

quote:
Originally posted by Dogfeathers

George, Thanks for the response , but I still remain confused. What you say I can believe playing a fretless banjo, but if you just arbitrarily move a bridge on a fretted banjo to a different scale length, the position of the frets stays the same, so these ratios you refer too are limited where they can move on the string length by the limitations of the position of the frets that were meant for a different scale length.
I.E. If you move the bridge a half inch either way from it’s correct position, the 12th fret harmonic will move to accommodate the new scale length —on the string—, but it will no longer be exactly over the 12th fret.

Pluck an open sting of any length and there will be a harmonic node at the half way point (12th fret) and the equivalent 5th, 7th and 9th fret. Those positions on the string will all change as the string length gets longer or shorter. If you fret the neck on a fixed position (or fret) of a given scale length and then shorten the scale length those nodes/harmonics will move accordingly along the string. The ratios you speak of will will act naturally on an open string, but as soon as you fret that sting it needs to mathematically match up with those nodes/harmonic positions to remain in tune.

Again I may be stressing minute differences that in the real world do not matter, after all I no longer have a teenagers hearing (working near F4’s in Vietnam took care of that) and the resultant ringing (and voices!) in my head make this hair splitting a moot point.
Sorry, I am still confused, but thanks George for trying, but so far I am still not convinced you can just shorten or lengthen a scale length on a fretted instrument just randomly, but still remain in tune on a fixed/fretted point that is not changing ratios at the same time the string length is changing.
Did I mention that my much older sister dropped me on my head frequently as a child to get me to “fit in” with the banjo crowd in latter life? Luckily my very thick head saved me!


When you move the bridge, you are in effect changing the scale length. You therefore, in order to maintain the same ratios, have to change the spacing of the frets (as you've indicated in your earlier post as to changes in the distances between frets with different scales). In other words, moving the bridge ruins the way the frets divide the scale; the distance between the nut and the first fret is now incorrect to produce the half-step that it should.

Each scale length has to be different in its fret spacing, because each scale has to have the same ratio between each fret; shorten the scale and everything else must be shortened. If a scale is changed by 1%, then each fret position must also be changed by 1%.

As for the harmonics, if you capo at the first fret, you have effectively turned the first fret into the nut, so you have to divide the distance between the first fret and the bridge in half to get the octave harmonic. That means you will get the octave harmonic at the 13th fret.

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