I hope that this is the right forum; it seemed like the closest according to it's description.

I have heard that changing the gauge of the strings on a particular guitar will also change the intonation. If this is true, then I assume that there is a "constant" involved. So, my question:

If I change to a lighter gauge string on my guitar, from .010-.046s to .009-.042s, will the bridge saddles tend to need to be adjusted towards the neck or towards the tail piece?

The 12th fret of my low E and G strings are just slightly sharp (about 3-5 cents), yet the saddles on my tune-o-matic bridge are "bottomed-out" as far toward the tail piece as they will go. I'm wondering if lighter strings will allow me to get the saddles back towards the neck.

Thank you to all who take the time to reply.
The lighter strings will allow you to move the saddles a bit more towards the neck yes. In fact, they might be right fully back TBH, but you are definately taking a step in the right direction in regard to string gauge and intonation.

EDIT:, Actually, if they are sharp at the 12th fret then they will be even sharper with lighter strings, as the strings are thinner therefore making for an increase in pitch. Are you measuring the pitch correctly? It seems odd that a guitar will not intonate with pretty standard gauge strings. Have there been any mods to the guitar? how high is the action?
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Last edited by Calum_Barrow at Aug 18, 2007,
Thank you for the replies. To answer the questions: The guitar just got back from the luthier last weekend, and a new bridge was installed. It's still a Gibson Tune-o-matic, but the one with the "inserts" (I don't know what to call them) that are pressed into the guitar. My old one had just the screws themselves going into the body, and only the the nuts moved up and down the screws when rotated. With this new one, the entire post moves up and down within the insert as it is rotated. Also, the nut was repaired, and the frets were dressed, with fret replacement for the first five. The action is about 5/64 bass, and 3/64 treble, at the 12th fret.

I used to use .009-.042s, but it was the luthier who suggested I switch up a gauge. I believe the reason for his suggestion is because I tune a half step flat. I'd kind of like to go back, though, as my style is metal, and I find them difficult to bend more than a whole tone.

I'm really not sure how precise the intonation was before I had it worked on. I've had this guitar over 15 years, and over time, the wear began to show. I became less and less picky about the precision of the set-up. Now that it's all fixed up again, these things matter again to me.

I didn't know that every time you change strings the intonation changes some. Perhaps I should just put on what I like for strings, set it as close as possible, and call it good. I admit, 3-5 cents is awfully close. I was just shooting for perfection.

I almost forgot; yes, I am sure that I am measuring the pitch correctly.

It bothers me, too, that the guitar will not intonate correctly. No one is perfect, but I feel confident regarding the luthier's work. Among others, his clients include Joe Perry and Peter Frampton. I do wonder what's up.