When I fret the Low E string (fat one) at the first and 12th frets I have .012 inches between the 6th fret and the string. Is this the amount of bow I want? I needed some relief to get the strings to quit buzzing, but im worried I may have too much?
Also, can adjusting the truss rod break the neck if it adjusted too often? Kind of like bending a metal wire back and forth? My neck is rose wood.
Edit: I've now lowered the relief to aproximately .006 or .007 my gauge wont go that low. Are those within the safe range? How low is still within the safe range? Also, can I damage the guitar if I put bigger/smaller strings on it without adjusting the relief before I tighten them?
If you are measuring the same gap at the 6th fret when fretting the 1st or 12th fret you are definitely set up wrong.
I am saying that based on my 2 guitars from,and set up by, 2 different shops.
You should have a much larger gap at the 6th fret when fingering the 1st fret than when fingering the 12th.
I may be way off but I always understood that the neck should be as strait as possible.
It sounds like your saddle/bridge is way too low given your description.
My strings are almost touching the first fret and about 1mm above my 12th fret and I was told my action was real low. But works fine for me.
You're confusing action and relief.
Action is the height of the string at the 12th fret... relief is the 'bowing' in the neck so that the elliptical vibrations of the string clear the frets. Relief is measured by using a straightedge along the entire fretboard length. The 'low' spots are generally .004-.012 out of true, so you need precision tools to measure it correctly. When you're fretting at 1 and 12, you're only attempting to guess at relief.... and you're not considering the whole fretboard, just a bit less than half.
The truss rod is to adjust relief, not action. Action gets adjusted by adjusting the saddle and/or nut. Although they both affect the 'playability' of the neck, way too many people try to adjust action by cranking on the truss rod.... which brings part two of your question:
No, you probably won't break the neck. It's not like working a coat hanger back and forth. Truss rods are very stiff, and have a limited amount of 'range' before they break. The neck is more flexible, so you're not in danger of busting the neck, just the truss rod, and that's a big deal to fix - the fretboard has to come off, the pieces get pulled out, the rod replaced, the fretboard reset... we're talking more than lunch money here.
Guitar teacher offering lessons in Plainfield IL
in response to the edit:
It's not really a "safe" range, but an effective one. I go for as little relief as I can get away with (without having to raise the action to avoid fret buzz). It does seem a reasonable amount though. The "safety" only comes into play if you start cranking down the truss rod and break it. You shouldn't be near that point.
Changing string guage will change the relief, but maybe not enough to require a second adjustment. There is no risk of damaging the guitar by changing string guage. Two possible exceptions would be if the strings are too large for the nut grooves and the nut cracks (a relatively cheap repair) or if the tension required for a larger string pulls off the bridge (or cuts into the bridge as has happened to me) (probably only an issue on an old guitar).
Changing string guage may, temporarily, throw off your intonation, so remember what yor original string guage is, so you can go back to it if the intonation is off.
