How does set up help intonation up the neck?

Kayak Jim

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OK I understand "set up" to mean (or at least include):

- checking/adjusting nut and saddle heights so strings are the optimal distance above the frets, aka "the action" (which I understand to be somewhere around 0.8 mm at first fret, 3 mm at 12th)
- checking/leveling frets to avoid any high or low ones that would tend to cause buzzing
- checking fret ends for sharp edges, other clean up type jobs

So lowering the strings will shorten the amount of string deflection required to fret the string, thus reducing the bending of the string sharp, thus improving the intonation impact. If action is as low as possible (without buzzing), intonation is also optimized (from a string bending standpoint).

Is there anything else a luthier (or set up tech) can do to improve intonation up the neck? Isn't it primarily a function of where the frets are installed, thus determined by build quality? So during set up, once the action is set, one can check the intonation but not correct it.

Sorry if this post is a bit anal. It's the engineer in me. Blow any or all of the above out of the water if I've got it wrong. I'm just trying to understand.

Jim B
 
The big drawback to most uke bridge designs is they don't take into consideration that string gauge affects intonation.

But adjustable bridge saddles seems like overkill (Although one company is adding this very feature to their ukes this year)

I think a middle ground is to do like some acoustic guitar builder and have a bridge saddle that wider. then file it at the point of best intonation for each string.

WP_000134.jpg

or a split saddle

bridge-and-saddle.jpg

But then again every video review I see of a ukulele shows some guy playing the 12th fret harmonics and then announcing the intonation is great. Most people (including myself) can't hear the difference between 440 hz and 443 hz. But that difference makes a huge impact as you play up the fret board.

To really zero each string into correct intonation you need a strobe tuner and adjustable saddles. Or change string gauge until the physics and math of it all works out.
 
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You also want the overtone of the string right over the 12th fret (1/2 way down the string). If it is off then the saddle wasn't installed in the proper place.
 
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