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Author Topic: Interesting truss rod issue.  (Read 2207 times)
headsup
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« on: February 07, 2015, 04:05:41 PM »

On one of my older Larrivee's (the L FM), the trusts rod affects the neck line in a non consistent way.
Basically the treble side of the fingerboard responds in a different way than the bass side, making for adjustment a bit of a head scratcher.

never seen this on a guitar of such high build quality before.
 I'm sure there's a reason, and a solution, just mentioning it in case any one else has ever had this happen.....
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Danny
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« Reply #1 on: February 07, 2015, 06:20:06 PM »

    This makes me think that the neck is starting to twist. I've never seen a Larrivee neck twist, but it's possible.
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« Reply #2 on: February 07, 2015, 08:08:32 PM »

I would be interested to know if this occurs with strings on and tuned to standard pitch, or unstrung, or both ways?
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« Reply #3 on: February 07, 2015, 08:30:55 PM »

so far just on and standard tuning.
It's in need of a fret dressing so I'll be looking closer when it's on the bench.
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Mr_LV19E
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« Reply #4 on: February 08, 2015, 11:02:30 PM »

More relief on the high or low E side? My necks seem to have a little more relief on the low E side, I always assumed it was because of the extra tension of the lower strings, I use 13/56. Its not a drastic difference, just subtle.
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« Reply #5 on: February 09, 2015, 12:37:39 AM »

couple things,

relief? when I set the bass side for relief (bow) the treble side is flat, treble strings have more tension than the bass strings I believe..

I use mediums on all my guitars. but for sure this neck needs a rest from string tension and a good fret levelling/dressing.....
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« Reply #6 on: February 09, 2015, 03:47:41 AM »

You guys seem to be familiar with these concepts, so I'll venture two questions:

1) Is there a standard for what portion of the neck truss rods "adjust"?

2) Is D'Addario the only company that actually publishes the tensions of their strings? (http://www.daddariostrings.com/Resources/JDCDAD/images/tension_chart.pdf)

There are various sites that explain the physics of string tension, but as D'Addario points out "By using different raw materials (nickelplated steel or phosphor bronze, etc.) or by varying the ratio between the core and the wrap wire, two strings with the same diameter, tuned to the same pitch, could have two different tensions."   (http://www.tothestage.com/upload/StringTension_1949.pdf)
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« Reply #7 on: February 09, 2015, 04:05:45 AM »

My understanding is that the whole neck moves. If it only effected the fret board then the board would just pop off.
  D R RARE strings are well known for having less tension at the same diameter as other makers.

   I have seen fret boards completely separated from the neck due to over adjustment.
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« Reply #8 on: February 09, 2015, 01:16:00 PM »

The double rods (only one adjusts, and not always both ways (check with manufacturers first), bur=t the adjustment is between the 3/4 fret up to about 9 or 10 fret, basically the middle of the neck, as I have experienced.
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« Reply #9 on: February 09, 2015, 03:22:08 PM »

I didn't even think about the double rod. My new OO has that type I suppose. Now that would bring in different issues, that are beyond my grasp.
I've taken apart several guitars to see how they are built and removed many necks but none with a dual rod.
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« Reply #10 on: February 09, 2015, 03:53:56 PM »

The double rods (only one adjusts, and not always both ways (check with manufacturers first), bur=t the adjustment is between the 3/4 fret up to about 9 or 10 fret, basically the middle of the neck, as I have experienced.


This has been my experience with adjusting truss rods (on acoustics) as well - it affects the part of the neck that is attached to the guitar body, but not the part of the fretboard that is over the top of the body. So when adjusting, it can sometimes look like you have a hump/bump at around the 12th-15th fret (on a 14 fret to the body neck).
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« Reply #11 on: February 09, 2015, 07:41:00 PM »

Just double checked my LS 12 fret and it has more relief on the low E side than the high E side, as I remember my others are the same. Actually on the high E side it is almost flat but does not cause any issues.
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« Reply #12 on: February 09, 2015, 08:44:07 PM »

How are you measuring the amount of relief?When I adjust a truss rod I hold down the low at the first fret and the 14th fret or the end of the finger board and eyeball it via space between the bottom of the string and the fingerboard,I also do the same thing with the high E,never really notice much of a difference.
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« Reply #13 on: February 09, 2015, 11:11:10 PM »

How are you measuring the amount of relief?When I adjust a truss rod I hold down the low at the first fret and the 14th fret or the end of the finger board and eyeball it via space between the bottom of the string and the fingerboard,I also do the same thing with the high E,never really notice much of a difference.

When I'm doing a set up that is pretty much the way I do it but I was just sighting down the neck, it's pretty easy to see, at least with my eye.
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« Reply #14 on: February 09, 2015, 11:52:37 PM »

How are you measuring the amount of relief?When I adjust a truss rod I hold down the low at the first fret and the 14th fret or the end of the finger board and eyeball it via space between the bottom of the string and the fingerboard,I also do the same thing with the high E,never really notice much of a difference.

I put the guitar on it's side in the playing position for most accurate measurement.  Then I put a straightedge on top of the frets in the middle between the D and G strings from the 1st to the 14th or 12th, wherever the body fret is.  Then I run a feeler gauge under the straightedge and over the frets, up and down the fingerboard to see how far in each direction it will go.  I find the gauge that will just fit under the straight edge at the lowest point of the neck, which is usually fret 7, 8, or 9, yet won't fit up or down from there.  I've never really bothered to check if the relief is different on the bass or treble side compared to the middle of the fingerboard.  I suppose I would do that if a neck looked visibly twisted.

The thickness of that feeler gauge is what I record as the current relief.  If that measurement is about .008" or more, I consider the relief to be on the high side and will try to get it down to somewhere between .004" and .006".  If I can't get the relief that low without buzzing, I assume there is some more adjusting to do elsewhere, and try and make any other appropriate adjustments at the nut and saddle to address the buzzing.  It may also indicate that the frets need levelling and dressing.
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« Reply #15 on: February 10, 2015, 02:19:18 PM »

Good advice all around for sure, I'm going to also put a set of the D'dario EXP19's on (light top/med bottom) strings on it to ease the treble side tension a bit.

 My straight edge is telling me there are also a couple high frets, just enough to get a bit of buzz where I don't want it.
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