Intonation Issues With My First Dulcimer Canjo-Guitar

Alright Guys and Gals,

So, I shied away from fretting an instrument based off my first and last build I tried fretting. I have been doing just fine fretless and just marking where the frets would be.

Here is my first attempt of a cookie tin guitar with a dulcimer scale. The scale length is 24 3/4" (I have a 1955 Epiphone Les Paul that is fairly spot on with that measurement). I simply transferred the measurements out and laid the necks side-by-side to compare.

I glued my frets in place, trying the bobby pin technique I had seen on here. The bridge position is fairly close to the edge of the tin where I have the bolt. The harmonics are true at the 8th fret and when in tune is sounds great chorded or open (with the exception that I think I need a few more sound holes).

My problem is, that the top string (an 'A' string from a standard pack, tuned to 'G') will not fret to the same note that the bottom 'G' string will. It's very close, but off as much as a quarter to a whole half a step. I have tried messing with the position of the bolt bridge, but once I get the top and the bottom string intonated to each other then the middle string is out.

What did I do wrong? I measured everything several times, and this time from the middle of the nut. Why would the bottom two strings fret in tune, but not the top? I am about to swear off of trying to fret anything! HELP!

mms_picture (7).jpg

Unfortunately you'll never get all the frets to play in tune with so much action at the nut.
This action is the side of a right angled triangle, the frets are layer out on the opposite side, but the string is the hypotenuse, if you understand trigonometry at all you'll see that the more action you add at the nut the more you'll exaggerate this problem. And getting it in tune at the mid point won't really get it in tune for the whole length unfortunately. This is why zero fretted necks intonate so sweetly. Try setting it up with a capo on the first fret and I'll bet you get a lot closer to getting it in tune, although this won't last when you remove the capo.

You're really gonna need a smaller nut IMHO.
Also, you've left yourself precious little room to play with the bridges position because you're right at the back edge there. You could consider adding this neck to a largest tin. I like to aim for my bridges around one third mark a boxes size, but some guys do like the 'spikier' sound of it near the edge, i acknowledge that. The answer here (IMHO) is next time do more frets clear of the box. I often do two full octaves clear of a box or tin, unless that box or tin is a real big one.

Looks great, don't get discouraged, everyone who's brave and tries new stuff screws the odd one up. Great effort :)

Replies

David L. March 18, 2014 at 6:03am

Hi Brian,

I realise you have measured and remeasured but looking at your photo it looks like the bolt bridge is too far back

Measuring from nut to the 8th fret and then adding this length again I get the bridge to be in the centre of the tin.

Also

Dividing the nut to the bridge bolt length I get the midpoint at the "X" (which would be around the 15th or 16th fret of a guitar and between dulcimer frets 9 and 10).
- Brian Revels > David L. March 18, 2014 at 8:31am
  
  Perspective of the image is off in the attached pic (quick shot from a bad camera phone). I saw what you were saying originally and thought I had really screwed up somewhere. I went home after work and remeasured. My measurements are accurate. I will repost some better pics once I am able (probably tonight).
  
  I will take a side shot of the string action as well. It does sound like the nut is probably my problem. To clarify for some who are confused, the top string won't intonate properly when chorded, while the middle and bottom strings will. I didn't think to try it with a slide, but will try that as well to see.
  
  Thanks for all the help and suggestions!
  - Brian Revels > Brian Revels March 19, 2014 at 8:04am
    
    Here are the pictures I promised. I had issues with my card reader and a new camera card. The action at the nut was actually closer to 3/16" to 1/4" (not sure where I got 3/8" from).
    
    I tried replacing the bolt at the nut with a much smaller machine screw. I then had to switch back to the bolt I originally used for the bridge (the rolled up piece of tin seen in the pictures looks cool, but started causing some strange string vibrations once the nut was switched). The results were very promising.
    
    Thanks for all the help. It looks like I just need to sink the original bolt (nut) down into the neck and I will totally be in business. I'm so glad I tried this with a generic tin I found and not one of my good ones. I have learned a lot with this build and have a feeling I still have more to learn from it.
    
    Thanks again! I will post a video once I get things the way I want them with it. :-)
    
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    - The Phrygian Kid > Brian Revels March 19, 2014 at 9:48am
      
      Great stuff.
      Ha I do remember the days when I had a particularly treasured tin or box.
      Fact is you can collect that shite far quicker than you can build em. I'm afraid you're destined to a cupboard or shelf chock full of favourite tins soon enough, just go for it.
The Phrygian Kid March 18, 2014 at 4:44am

Unfortunately you'll never get all the frets to play in tune with so much action at the nut.
This action is the side of a right angled triangle, the frets are layer out on the opposite side, but the string is the hypotenuse, if you understand trigonometry at all you'll see that the more action you add at the nut the more you'll exaggerate this problem. And getting it in tune at the mid point won't really get it in tune for the whole length unfortunately. This is why zero fretted necks intonate so sweetly. Try setting it up with a capo on the first fret and I'll bet you get a lot closer to getting it in tune, although this won't last when you remove the capo.

You're really gonna need a smaller nut IMHO.
Also, you've left yourself precious little room to play with the bridges position because you're right at the back edge there. You could consider adding this neck to a largest tin. I like to aim for my bridges around one third mark a boxes size, but some guys do like the 'spikier' sound of it near the edge, i acknowledge that. The answer here (IMHO) is next time do more frets clear of the box. I often do two full octaves clear of a box or tin, unless that box or tin is a real big one.

Looks great, don't get discouraged, everyone who's brave and tries new stuff screws the odd one up. Great effort :)
- Brian Revels > The Phrygian Kid March 18, 2014 at 8:36am
  
  Thanks Kid. Yeah... I messed up on this neck when making it for a box build (got in a hurry and misread my measurements for the box and didn't take into account the lid). I typically try to do the same with the bridge position as you do, but was hoping to be able to salvage a good piece of red oak that was already cut and sanded.
  
  Thanks for the suggestions. Gives me something to try rather than having to start over with the neck. :-)
Barsymes Cratchnee March 17, 2014 at 11:39pm

Very confusing...you can intonate the top and bottom strings fine, but the middle string is close to 1/2 step off? I'm not sure what could explain that.
Richey Kay March 17, 2014 at 4:32pm

Does this happen all the way up the neck or is it mainly towards the bridge? How high is the action at the nut? If its too high the fretted notes will sharpen, and it will be more obvious with thicker strings...
- Brian Revels > Richey Kay March 17, 2014 at 9:41pm
  
  The action is about 3/8" at the nut. I am using 11 gauge electric strings (all I had laying around). I reworked the bridge a bit. The sound is better, but the notes fretted are not (still the same issue with the top string). It is all the way up and down the neck. Do you think it could be the angle coming from the bridge? There is not much of a downward angle like on a guitar; it's fairly flat (maybe around 5-10 degree angle).
  
  From the nut to the 8th fret is around 12½". Measuring from the 8th fret down the bridge should be at the edge of the tin (as I thought). That's probably why re-working the bridge helped the sound quality. I am able to get clearer harmonics at the 4th and 8th frets. The harmonics are spot on.
  
  I will attach a better picture when I get a chance.
  - Richey Kay > Brian Revels March 18, 2014 at 3:24am
    
    Could you confirm that the intonation is fine with a slide, but not when you fret the notes?
    
    The nut action at 3/8" is nearly 10mm... if you're trying to fret that it will throw the notes out completely. 1mm is more like it. In order to fret a note you are effectively stretching a string... which will cause it to sharpen. Is there any way you can either fit a different nut (zero fret or similar) or sink the bolt into the neck to make it lower?
    
    A picture from the side, at a higher resolution if poss would be really helpful.

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