Uke Bridge Problem... Need Sage Advice

[SIx String Chef]

So... my wannabe-Stepson-in-law knows I am delving into the whole guitar tech and repair thing, so he brought up to my home shoffice (workshop/office) a Kala brand uke (I think it's a soprano, all mahogany, model KA-C) that he's had for some time, for me to give it a once-over and see if I can help him fix the strings constantly going out of tune and whatever else I could find.

So, I did the perfunctory cleanup, fret polishing, fretboard oiling, machine head tuner nut tightening, cutting off the excess nylon string, etc. Also rewound the strings properly on the tuners, as the 1st and 2nd were wound the wrong way. This, along with constant retightening and stretching of the strings, seems to have made the strings keep their tuning.

However... The 3rd string (from bottom up), C, has that distinctive sitar-y not-quite-the-right-note-pitch-no-matter-how-fine-you-tune-it double-y note sound that to me spells some bridge issue.

I'm thinking the lack of visible slotting for the strings on the bridge may be to blame, but all the other strings sound decent. So, what say you, TTR brethren?

As usual, would really appreciate your words of wisdom and guidance to fix this issue.

 

[Amp Mad Scientist]

So... my wannabe-Stepson-in-law knows I am delving into the whole guitar tech and repair thing, so he brought up to my home shoffice (workshop/office) a Kala brand uke (I think it's a soprano, all mahogany, model KA-C) that he's had for some time, for me to give it a once-over and see if I can help him fix the strings constantly going out of tune and whatever else I could find.

So, I did the perfunctory cleanup, fret polishing, fretboard oiling, machine head tuner nut tightening, cutting off the excess nylon string, etc. Also rewound the strings properly on the tuners, as the 1st and 2nd were wound the wrong way. This, along with constant retightening and stretching of the strings, seems to have made the strings keep their tuning.

However... The 3rd string (from bottom up), C, has that distinctive sitar-y not-quite-the-right-note-pitch-no-matter-how-fine-you-tune-it double-y note sound that to me spells some bridge issue.

I'm thinking the lack of visible slotting for the strings on the bridge may be to blame, but all the other strings sound decent. So, what say you, TTR brethren?

As usual, would really appreciate your words of wisdom and guidance to fix this issue.

The break angle of the string over the nut, or over the bridge saddle.
Slotting the saddle does not usually fix that problem unless the slot is cut at the correct angle...





And so if you are getting sitar sound, it's probably because the string is flat over the saddle and there is no proper break angle.

 

[StrumerJoe]

The break angle of the string over the nut, or over the bridge saddle.
Slotting the saddle does not usually fix that problem unless the slot is cut at the correct angle...

View attachment 81489
View attachment 81490
View attachment 81491

And so if you are getting sitar sound, it's probably because the string is flat over the saddle and there is no proper break angle.

^^^ That's exactly where I'd start ^^^

 

[RVA]

The nut slot may be to deep. If is is a bone nut, consider the baking soda/superglue trick

 

[StrumerJoe]

The nut slot may be to deep. If is is a bone nut, consider the baking soda/superglue trick

The baking soda fix is temporary. I prefer, in a pinch, to use the same material as the nut & superglue, but still it's a temporary fix. Touring techs use that method a lot because they are unlikely to have a combo sander and nut material handy like a luthier's or tech's shop. The baking soda, or dust trick, is great for a quick diagnosis though. It will confirm quickly if that is indeed the source of unwanted noises.

The best solution, when possible, is to just make a new nut out of a blank. IMHO YMMV

 

[SIx String Chef]

HEre are a few pictures of the bridge and nut.

Strings 4 and 3


And strings 2 and 1


the bridge is basically unslotted, save for a very slight dimple for each string (shown in the red highlights). I'm guessing this may have happened just by the pressure the strings apply on the bridge, not by design.

The nut slots seem to be pretty much at very best quite flat, but It seems to me that they slope from the back toward the fretboard, leaving the break surface at the back, if any at all. Depth in the back of the outside slots is shallower, i'd like to think, to accomodate the thinner gauge strings.







Thoughts?

 

[Amp Mad Scientist]

HEre are a few pictures of the bridge and nut.

Strings 4 and 3
View attachment 81582

And strings 2 and 1
View attachment 81583

the bridge is basically unslotted, save for a very slight dimple for each string (shown in the red highlights). I'm guessing this may have happened just by the pressure the strings apply on the bridge, not by design.

The nut slots seem to be pretty much at very best quite flat, but It seems to me that they slope from the back toward the fretboard, leaving the break surface at the back, if any at all. Depth in the back of the outside slots is shallower, i'd like to think, to accomodate the thinner gauge strings.

View attachment 81588

View attachment 81589

View attachment 81590

Thoughts?

That's koa wood. The nut slots are cut pretty rough, I would say.
The slots are too flat, there's no break angle.