1

(12 replies, posted in Guitars and accessories)

The truss rod tension is only adjusted to control relief, not to affect action height.  The "relief" is a small amount of bow of the neck under string tension, between the nut and the portion of the neck that's too thick to flex -- around the 12th fret.  It's called "relief" becausse it allows a small amount of room for the strings -- especially those big bass strings -- to vibrate without touching the frets.

If you have a 12-inch straight edge, you can lay it on the neck just off the nut so it's touching the first fret. The other end of the 12-inch straight edge (a good quality ruler, perhaps) will be around the 12th fret on the most common size steel-string guitar neck. With the straight edge touching the 1st fret and the 12th, check the space below the straight edge, above the 5th fret. 

If the 1st and 5th and 12th frets all touch the straight edge, that's zero relief. Most finger pickers and others who don't pluck the strings hard can be happy with zero or very little relief.  If there's one thirty-secondth inch (half a sixteenth) between the 5th fret and the straight edge, that's too much -- probably way too much.  Tightening the truss rod reduces the relief, but is a dangerous adjustment to play around with.  The truss rod can be broken or the wood might be damaged. The truss rod is only turned a small fraction of a turn at a time and then the instrument played for a while to let it stabilize before another measurement.  It will always be recommended to have that done by a "pro."

If you don't have that high quality 12-inch straight edge (like a machinist's rule), you can still check the relief.  In that case, you fret the same string at the 1st fret and the 12th fret, and again check the clearance between the 5th fret and the string.  You're using the tensioned string as a straight edge, and it's always correct.  If you have a capot, you can put that on the 1st fret, fret the string at the 12th fret, and have a hand free to try to gage the relief. That's a little harder to do when you're using the string for a straight edge, because the string may flex as you try to measure.

2

(12 replies, posted in Guitars and accessories)

Sticking with it "for now" is your business, but 1/8 inch all strings IS too high.  If your frets have been properly leveled, you should be able to set the low E at 3/32 inch and the high e close to 1/16 inch, without excessive buzzing.  Those are small dimension differences but large differences in how hard it plays.  (I've done a LOT of these.)

3

(12 replies, posted in Guitars and accessories)

Well, it looks like this thread is still going, the first I've been here.  I'll throw in another two cents worth. 

I'd guess the nut filing they did at first was okay.  That's always a compromise between buzz and too-high on the first few frets.  When you began to play up the neck and get buzzing, PROBABLY it had nothing to do with the nut.  It's POSSIBLE to get buzzing because of small vibration contacting frets between the one you're fretting and the nut. But their diagnosis of uneven frets at fault is ten times more likely. 

Seems like MAYBE they got the action too high at the saddle (bridge).  You check that first by measuring the heights of the strings above the 12th fret.  Should be less than one-eighth inch on the bass E or 6th, and 3/32 inch on the treble strings.  They should not have got this wrong, and don't be surprised if you find the action not overly high by that measure.  The frets have been leveled now, so you can probably get by with filing or sanding off the bottom of the saddle to get the action lower.  I've seen lots under 3/32 on the bass and about 1/16 on the treble, but you have to work down a little at a time, checking on buzz as you go.  If you go too far, it means another new saddle or a shim is required.

One other thought.  If they took A LOT off the frets, the first or first few in particular, and did  not re-check the nut, it's possible the slots in the nut are again not deep enough. But as a practical matter that will affect only the first frets.  If the nut were so high as to cause high action up the neck, I would be painfully at the first fret. Your set-up person should also check the relief at the outset, probably did.

Good luck.