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Oct 25, 2020 - 10:59:09 AM
465 posts since 3/11/2004

I don't know if this has been perceived as a problem by any builders or setup people, but here is the "problem" as I perceive it:

Sometimes I've noticed that the 5th string is much closer to the 4th string when compared to the spacing of any other 2 adjacent strings. This is most noticeable at the 5th fret (if the pip is located too close to the 4th string). One solution is to have the pip in line with the fret so that the spacing can be made equal to the spacing of other adjacent strings, but in traditional Gibson pip placement, sometimes there isn't room to locate the pip far enough from the 4th string to accomplish this.

My method for achieving equal string spacing up and down the neck (and at the 5th fret) is done by installing the pip where desired, and locating the slot for the 1st string where desired. Then the 1st string and 5th string are installed and the distance between the 1st and 5th strings are measured, both at the bridge and at the 5th fret. Since the distance between the 5th fret and the nut is very close to 1/4 of the total scale length (since it is the location of the 2nd octave harmonic), this can be used to calculate the spacing of the strings at the 5th fret and at the nut. I have attached a couple of spreadsheets showing the formula used for getting the string spacing at the nut (which will result in equal string spacing at any fret). The more complex formula is for the distance between strings 1 and n-1 at the nut (n = 5 for a 5 string banjo), and the less complex formula in the second spreadsheet is for the spacing of the individual strings at the nut (which is pretty obviously the distance between strings 1 and n-1 divided by (n-2).

I put in a few measurements using a bridge with Crowe spacing, and one of the lines shows how the formula works if the spacing at the 5th fret is the same as at the bridge (the spacing at the nut will be the same as at the bridge in this case - showing that the formula works).

I hope this might be of use to some builders and repairmen (if they haven't already thought of the same solution to the "problem").

Oct 25, 2020 - 11:20:02 AM

465 posts since 3/11/2004

Here are the spreadsheets with formulas (they didn't upload when I originally posted):


Oct 25, 2020 - 11:35:40 AM

465 posts since 3/11/2004

Since the formula is not easy to read in the attachments, here is a basic one that works for 5 string banjo (though the spreadsheet will work with instruments with different number of strings, as long as there is one less string present at the nut than at the bridge): total distance from strings 1 to 4 at the nut is the distance from strings 1 to 5 (measured at the 5th fret) minus the adjacent string spacing measured at the bridge. The distance between adjacent strings at the nut is obviously 1/3 of the total distance between strings 1 and 4 at the nut.

Oct 25, 2020 - 2:21:08 PM

Alex Z

USA

4046 posts since 12/7/2006

"I hope this might be of use to some builders and repairmen (if they haven't already thought of the same solution to the "problem")."

I sure hope so too.  There are plenty of banjos, new and used, where the 5th string is too close to the 4th string.  Sometimes the 5th string is much too far from the edge of the fingerboard also.

The slot on the pip doesn't have to be in the center of the pip, either, and that gives the builder a little more room.

And don't get me started on the builders who position the 5th string peg hole such that you can't get a capo cleanly on the 4th fret.  What are they thinking?  smiley

Some guitar builders are aware of the equal spacing situation and so take into account the diameter of the strings also.  6th to 5th .056 to .045 leaves noticeably less room in between compared to 2nd to 3rd .017 to .013

Oct 25, 2020 - 2:22:53 PM

3966 posts since 10/13/2005

String spacing is a big deal with the five banger. Some builders never seem to get it right. It's the first thing I look at when I pick up a banjo. As a beginner banjo player, it took me a while to realize that having the 4th and 5th string jammed too close together was an unnecessary hindrance to clean banjo playing and a sign of improper neck building. When a builder fails to build the neck wide enough at the fifth fret, his choice is either to jam the 4th and 5th strings close together while leaving strings 1-4 spaced equally, or, space strings 1-5 equally which leaves a lot of unused banjo neck real estate between the 4th string and the edge of the neck from the nut to the fifth fret. The latter recently happened with me with a custom build. The nut was 1&5/16", the strings were spaced evenly, but the measurement of the width of strings 1-4 was equal to another banjo that had a nut of only 1&5/32". It had the tell-tale sign of a lot of neck space between the 4th string and the edge of the neck from the nut to the 5th fret. I know to some 5/32" of an inch is no big deal but so much of banjo playing comfort can be determined by what seems like insignificant numbers/measurements.

Thanks for the opportunity to go on another of my pet peeve rants about banjo necks too narrow at the fifth fret. I periodically do this so beginning banjo players don't have to stumble along like I did wondering why one banjo is easy to play and another isn't. banjered

Oct 26, 2020 - 1:16:54 AM

465 posts since 3/11/2004

I agree that the best solution is to have strings 1 to 4 spaced optimally at the nut, and then have the neck wide enough just behind the 5th fret so that even a Gibson type pip placement can be positioned far enough from the 4th string to achieve equal string placement.

If the neck is too narrow, I like the way that Ome and Prucha (and a Goldstar frailing banjo that came out recently) have the pip positioned like the dot on the letter "i", with the 5th fret shortened enough to allow placement of the pip inline with the shortened 5th fret. A spike (which think Deering is still using and which Prucha used to use) for setting the 5th string location at the 5th fret will usually allow the 5th string to be far enough from the 4th for equal string spacing, but some people like the 5th string to be slightly elevated relative to the 5th fret, so the spike method won't work unless something else is provided to lift the 5th string a bit above the 5th fret. This could be something as simple as 1/2 of the ball end of a guitar string (cut in an arch configuration and superglued to the 5th fret). A spike could still be used to guide the string so it doesn't pull on the sides of the ball end arch, but if the 5th string runs in a straight line from the bridge to the 5th string peg spool, then a spike might be unnecessary.

This topic (about inline pips, an arch over the 5th fret, spikes instead of pips, etc) is discussed in many archived threads.

Oct 26, 2020 - 8:58:09 AM

11005 posts since 10/27/2006

>The nut was 1&5/16", the strings were spaced evenly, but the measurement of the width of strings 1-4 was equal to another banjo that had a nut of only 1&5/32". It had the tell-tale sign of a lot of neck space between the 4th string and the edge of the neck from the nut to the 5th fret. I know to some 5/32" of an inch is no big deal<

Your math isn't making sense.

Oct 26, 2020 - 9:02:25 AM

465 posts since 3/11/2004

I think it makes sense: 1 5/32" + 5/32" = 1 5/16"

Oct 26, 2020 - 11:26:15 AM

11005 posts since 10/27/2006

quote:
Originally posted by schwimbo

I think it makes sense: 1 5/32" + 5/32" = 1 5/16"


Not if we're talking the 5th fret.

Oct 26, 2020 - 12:30:57 PM

3966 posts since 10/13/2005

Thank you. To clarify, on both banjos I measured the width of strings 1-4 at the first fret wire. They were identical even though one nut was 1&5/16" and the other was only 1&5/32". So the 1&5/16"  nut-banjo builder can claim he has a wide neck/nut banjo but because he made the neck too narrow at the fifth fret – thereby jamming the strings together – he ends up with a string spacing no better than the banjo with a 1&5/32" nut which is pretty narrow as banjos go. I actually ordered the custom 1&5/16" nut banjo to get away from having that too-narrow-for-me 1&5/32"  nut banjo but unfortunately  ended up with a banjo with no better/increased string spacing than the one I started out with. It was frustrating for me because I specifically asked the builder to be  sure to make the neck wide enough at the fifth fret area. I had other specifics I requested, even sent pictures of what I was desiring, but for reasons I never found out the requests were ignored. Again, this might seem like minutia to some but these details can make all the difference between a comfortable-to-play banjo and an uncomfortable one.  banjered

Oct 26, 2020 - 1:39:03 PM

mbanza

USA

2271 posts since 9/16/2007

I find fifth spacing as: Spacing at nut + ((spacing bridge - spacing nut) x 0.75) = spacing fifth.

The cutaway for the fifth peg should be about 6.5mm or 3/16 inch deep so that the string runs straight across the fifth nut to the inboard side of the capstan.

Oct 26, 2020 - 2:28:07 PM

mbanza

USA

2271 posts since 9/16/2007

Correction: Spacing at nut + ((spacing bridge - spacing nut) x 0.25) = spacing fifth.

Oct 26, 2020 - 8:00:49 PM

465 posts since 3/11/2004

I agree with your last formula, though if you already know the spacing at the nut (because it is slotted), then you can just see how far apart the individual strings are at the 5th fret and position the 5th string that same distance from the 4th to get equal spacing (obviously).

It seems to me that a better use of the same equation would be to derive the spacing at the nut from knowing the distances between strings 1 and 5 at the bridge and at the 5th fret (by only having the pip positioned and slotted and the nut slotted for the 1st string). Then the spacing at the nut could be determined, and equal spacing achieved - with the only drawback being that there might be excess fretboard (for the 4th string) or possibly too little (again for the 4th string) depending on how the neck was cut between the 5th fret and the nut.

This is what banjered had pointed out in his posts (too wide a fretboard for the spacing at the nut, or conversely too narrow a spacing at the nut for the width of the fretboard). Since there is usually full fretboard width at the 5th fret, to make full use of the width of the neck, it seems better to space the strings as desired at the nut, and then install the pip inline with an abbreviated 5th fret (or do some equivalent procedure) to ensure equal spacing with desired spacing at the nut).

Of course a builder could even screw this up by having the neck not being sufficiently narrow between the 5th fret and the nut, so that the 5th string could never be far enough from the 4th string to achieve equal spacing if the full width of the nut was used in determining the spacing at the nut.

Oct 26, 2020 - 9:07:43 PM

mbanza

USA

2271 posts since 9/16/2007

schwimbo said: " . . . it seems better to space the strings as desired at the nut . . ."

You're right, and that gives you both nut and bridge spacing to plug into the formula after which you will be able to measure neck width at fifth and easily see if it will accommodate an equally spaced fifth string.

I like millimeters for doing these things and spacing for any nut is (Width - 6) / 3 . After using the fifth spacing formula, the required width at fifth is (Spacing x 4) + 6 . That may be as good as can be done with an existing neck.  A full-sized drawing of the fingerboard and the string courses is very useful for evaluating the space available.

Your idea to rearrange the formula to get other results is a useful one.

Edited by - mbanza on 10/26/2020 21:12:57

Oct 26, 2020 - 9:31:03 PM

465 posts since 3/11/2004

I see now why you wanted to derive the spacing at the 5th fret (and the width of the neck there). You are looking at this as something to be calculated before the neck is built / shaped, which of course would make lots of sense to avoid having not enough width (or too much width) to fit with the desired spacing of the strings. I guess I was assuming the neck was built, but the problem was then to use the existing width and string distance from 1st to 5th string to determine the spacing at the nut.

To rule out the problems that banjered encountered, it is probably better to have the neck dimensions calculated in advance (from knowing how wide you want the neck or string spacing to be at either the 5th fret or the nut).

So your use of the equation makes good sense if you know the desired nut spacing - you can then figure out how wide to have the neck at the 5th fret. The formula could be adjusted to calculate the spacing / fretboard width at the 12th fret.... spacing = (spacing at nut + spacing at bridge)/2 or actually anywhere on the neck. Spacing at any location would = (distance to bridge/scale length) x nut spacing + (distance to nut/scale length) x bridge spacing.

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