Three string guitar

[Bombard]

Hi all. Newbie here. I have built several three string guitars. Typical bolt for the nut and Home made bridge. Having trouble dialing in the neck. When tuned in GDG the twelfth feet harmonic is right on but when I travel up the neck most all fret positions are sharp  my neck is straight and on the last guitar I built I flattened and filed the frets. String height on all are a little different but all are playing the same. I used a paper template I purchased for the 23” scale and I was as accurate as I could be when laying out.  Any suggestions?  Also tried to attach pics but said the two pic file was to large? Any one know how to attach pics?  

 

[MiKro]

37 minutes ago, Bombard said:

Hi all. Newbie here. I have built several three string guitars. Typical bolt for the nut and Home made bridge. Having trouble dialing in the neck. When tuned in GDG the twelfth feet harmonic is right on but when I travel up the neck most all fret positions are sharp  my neck is straight and on the last guitar I built I flattened and filed the frets. String height on all are a little different but all are playing the same. I used a paper template I purchased for the 23” scale and I was as accurate as I could be when laying out.  Any suggestions?  Also tried to attach pics but said the two pic file was to large? Any one know how to attach pics?  

 

First welcome to PG.

locating the bridge accurately is the most common problem from an intonation standpoint. I might suggest that you use the fret calculator on Stewmac.com site. That would be a good start to help overcome inaccuracies in your fret slot location and bridge saddle placement. Most likely choose acoustic style for the type of bridge saddle placement you are using. As far as scale that would not change from electric or acoustic.

MK

[Bizman62]

Welcome to the addiction!

To me your issue sounds like your paper template is not accurate enough. The reason can be in the printing process as there can be options like 'scale to fit the printing area' which easily can make the image up to 10% smaller than intended without you even noticing. WIth such a misprinted template you still can get the 12th fret harmonic spot on as it's halfways of the scale but especially the upper frets will be off as they're so narrow.  ½mm off does less harm on a 35mm fret than on a 15mm fret.

A fret calculator as @MiKro suggests or just a simple chart telling the distance from the nut to each fret would tell you if your template is off.

[curtisa]

9 hours ago, Bombard said:

When tuned in GDG the twelfth feet harmonic is right on but when I travel up the neck most all fret positions are sharp

I suspect there's some missing detail here. How are you determining the accuracy of the twelfth fret position exactly? The quick-and-dirty method of checking intonation accuracy is to compare the twelfth fret harmonic to the twelfth fretted note and check that they are as close to the same pitch as each other as possible. The 12th fret harmonic by itself doesn't reveal anything important regarding the accuracy of the fret positions.

Most all fret positions being sharp up the neck (up the neck past the 12th fret? The whole way from the nut upwards? Starting off OK but progressively getting worse the higher up you go?) suggests there's an error in the placement of the bridge or frets, but a bit more information will help us guide you to some things to try out.

[Bombard]

Thank you all for your help. I got my paper fret template from CB Gitty. They are a supplier for three string guitars.  I have tried adjusting the bridge on all three guitars and get the same results. After thinking about your suggestion I am thinking it must be the template. I assume once the frets are cut in my only option is to build a new neck with more accurate fret locations? I will check out the fret calculator. 

[Bizman62]

1 hour ago, Bombard said:

I assume once the frets are cut in my only option is to build a new neck with more accurate fret locations?

Not necessarily, you can also pull the frets off, fill the slots with veneer and re-measure and re-cut the slots.

[Bombard]

Thank you both for responding. I got the paper template from CB Gitty, a cigar box supplier. When playing each string open and in tune and playing the twelfth fret harmonics its in tune. The three guitars I have made all have the same issues. I used the same template on all three.  Thanks for the tip on the veneer. 

[Bombard]

So I looked at a fret calculator and wow! How in the world do you get a ruler with such small increments? I a carpenter and my ruler only goes up to 1/16. I dont think I even know how to measure that small.  Would I be better buying a good meta fret layout tool?

[curtisa]

1 hour ago, Bombard said:

When playing each string open and in tune and playing the twelfth fret harmonics its in tune.

That doesn't verify that the fret or bridge placement (or intonation adjustment, if any) is correct. The open string will always be the same pitch as the 12th fret harmonic, no matter how you tune it or how long the scale length is. All the 12th fret harmonic shows is that the midpoint of the string is exactly an octave above the open string pitch. Its the comparison of the 12th fret harmonic vs the 12th fretted note that matters.

If you're using a 23" scale as the basis of your build try taking a measurement from the nut to the 12th fret - you should get 23"/2 = 11.5". The distance between the 12th fret and the bridge should also measure 11.5" (actually a little more than 11.5" to account for any intonation compensation built in to the instrument, but it should be close). If fretted notes are coming in sharp no matter what position you'll probably find that the 12th fret appears to measure less than 11.5" to the bridge.

[curtisa]

BTW, if you're wanting to attach pictures to your posts, New Members have an upload limit of 500kB per post. Provided the total upload attachment size (which includes multiple files summing up to 500kB) is less than 500k you should be OK. That restriction gets lifted once you exceed 25 posts on your account.

[Bombard]

Just check the twelfth fret measurement from the end of the fret board face of the nut and it is 11 1/2". I thought that the measurements came off the center of the nut but after just reading more I found it should be taken from end of the fret board. When I originally set up the bridge I set it off the center. Just moved it to where it is supposed to be and sound is improving. I think now I need to play with the nut height. I will send some pics.  

[Bombard]

[Bizman62]

11 hours ago, Bombard said:

When I originally set up the bridge I set it off the center.

Seems you've found at least one culprit! Well done!

Yes, the scale is measured by the free string length and the leaving edge should be the highest point of both the nut and the bridge as shown in the illustration below. Also note that the measured scale length isn't accurate, it only gives you a starting point to find the right distance and angle for the bridge. The thickness of the strings, the action and your playing style all affect to the tuning.

[ShatnersBassoon]

11 hours ago, Bombard said:

 

That last guitar has quite a cool finish! How did you achieve that? Is it copper?

[Bombard]

Thanks guys. Your advise is appreciated. The last guitar and the one in the middle of the picture of three are copper. The middle one was roof flashing I saved off a job. That’s natural patina and the last one, color is done with heat. 

[Charlie H 72]

Beautiful guitars! Thanks for sharing. So-you have verified that nut to 12th fret to nut is the correct distance, how about 12th fret to bridge (11.5”) and nut to bridge (23” to start-then small adjustments to compensate for the factors Bizman noted)? Based on a quick visual check of your images it looks like the bridges are too far back. 

Edited March 5, 2021 by Charlie H 72

[Bombard]

Yes,  the bridge is 11.5" from the 12th fret.  I am thinking of using an adjustable bridge on the next guitar.  Will this help with adjustments?

[Bizman62]

23 minutes ago, Bombard said:

I am thinking of using an adjustable bridge on the next guitar.  Will this help with adjustments?

As that's sort of a trapeze layout on those, a bridge you can slide to the desired distance and angle is sufficient. That's what has been done on archtop jazz guitars 'forever' so that's no redneck engineering.

[ScottR]

On 3/4/2021 at 2:24 PM, Bombard said:

Just check the twelfth fret measurement from the end of the fret board face of the nut and it is 11 1/2". I thought that the measurements came off the center of the nut but after just reading more I found it should be taken from end of the fret board.

You may be both right and wrong. The measurements need to be taken from the break angle of the nut and bridge. See @Bizman62's illustration. Typically the break angle of the nut and the end of the fretboard is the same place. You are using a round bolt for a nut and a round bridge as well. The break angles of both of those are in the center of the nut and bridge--the highest point.

If your fret template does not account for the big round nut and in fact is meant to be used with a typical nut that has the break angle right at the edge of the fretboard--and most do-- all your fret measurements from the nut will be wrong.  If you find that to be the case you can move the nut closer to the first fret by half the width of that bolt and it will true up those fret measurements.

If the template does account for the type of nut you are using.....then nevermind.

SR

[Bombard]

That makes sense. I When I started building these my interest was in the folk art look.  I now want to learn how to make the guitars sound as good as they can first and the look second.  I will build a brass or copper nut.  My frets are accurate and string height is good but still could not get it intonated.  I will let you all know how it sounds after I change the nut.  Thanks again for all your help.   

[Bizman62]

Changing the nuts sounds like a good plan. The thick round bolts as nuts clearly take the highest point way too far back.

Looking at your bridges, aren't two of them hollow? If so, cutting a slot and adding a fret might also help to get the fine tuning right. That would raise the strings a bit, so additional tweaking would be required if you take that route.

[Bombard]

The nut is a copper pipe.  I like that idea.  I will see if I can make one like that. I had another question about neck and fret board  finish. I lacquer a good finish to use?