I have a Fender Hellcat Guitar. I just swapped from 12s to 13s, and anticipated some intonation problems, but to my surprise, only 1 string was affected.

The G string. It goes WAY flat form 12th Harmonic to 12th Fretted. Should I cut into the bridge with a knife to make a deeper grove? Or mess with the Nut? Not sure how to fix just one string separately.

EDIT: Intonation on other strings are fine, and the action is where I want it
Guitars: ESP LTD H-1001FM ACSB, Epiphone SG Special
Acoustics: Fender Hellcat, Mitchell 12-string
Amps: Roland Microcube, Peavey Vypyr 15W
Effects: Digitech RP355
no. making a deeper groove will probably not improve intonation. you need to have the saddle looked at - and probably intonated - by a qualified guitar tech or luthier.
Quote by Skeet UK
I just looked in my Oxford English Dictionary and under "Acoustic Guitar", there was your Avatar and an email address!
I'm not certain about the "Hellcat", but my "Sonoran" only has a 3/32" wide saddle, rather than the 1/8" wide saddles on many other guitars.

The 1/8" wide saddles are generally made with an intonation offset on the B string. There really isn't enough meat on the narrower Fender and Martin saddles to provide a meaningful adjustment. The reason for the B string offset, is due to the string tuning, (I believe), which is a major 3rd differential from its neighbors, rather than the perfect 4th of all the rest.

It seems to me that grinding a slot deeper in a saddle, thereby having the G string sit lower than the others, would provide an "interesting" playing challenge.

If the heavier medium string set has raised the action overall, were you lower it, the fretted string intonation would likely improve a bit. This because you're bending the strings less, which is causing less pitch shift when you fret them.

My first impulse is to tell you to simply go back to the acoustic light strings your guitar was likely shipped with, as they place less physical stress on the instrument. It may "live longer", with the lighter strings. There is roughly a 15 to 20 pound tension increase, when going from lights to the mediums.

Just for the record intonation is, and always has been an issue with acoustic guitars, as they lack the individual saddle adjustments of most electrics. So, you're not suffering alone.

The G string you installed could simply be defective, but you'll have to wait until the next change to find out.

Martin saddles do have intonation offset, but it is minimal, and IDK if it would only work for Martin's own guitars. (Length could be a small issue)

Here is the wider "Taylor" style saddle, "fully" compensated: (Invalid img)

Do not "mess" with the top nut AT ALL. Were you to grind an offset on that, it would increase the distance to the 1st fret, which in my mind, would cause more serious intonation issues.
Last edited by Captaincranky at Apr 7, 2013,
you know.... we haven't had a good truss rod adjustment suggestion in months. maybe its time.
Quote by stepchildusmc
you know.... we haven't had a good truss rod adjustment suggestion in months. maybe its time.
Oh a truss rod adjustment is it now? Pish tosh, you would use a mere child's toy plastic gun, to confront the dreaded juggernaut that is the out of control intonation monster?

Ya needza git a neck jobbie like thissy here:

Now that's a fifty caliber solution....
Last edited by Captaincranky at Apr 7, 2013,
where do you find this shit? that some funny stuff ! and for the record, the only accurate fitty is a Barrett .416. nasty piece of business that one is. all the rest are a spray n pray. glad i traded up to guitars.