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Strange truss rod situation
https://luthiersforum.com/forum/viewtopic.php?f=10137&t=55254		 Page 1 of 1
Author:  Conor_Searl [ Mon Sep 12, 2022 4:30 pm ]
Post subject:  Strange truss rod situation
I have a 2012 Music Man John Petrucci guitar in the shop that just moved out here to the west coast of Canada from the prairies. This is about as big a change in environment as a guitar will typically ever experience, and this is likely where my problem is stemming from. The guitar is of a high quality and as far as my experience counts for anything, Music man makes a consistent and reliable product.

It appears that there is a hump around the 3-4 fret, and then excessive bow in the middle of the neck. The problem seems pronounced when using the string as a straight edge, with a notched straight edge the problem is less extreme. The truss rod seems to work fine, it moves smoothly and predictably. When I back the truss rod all the way off without any strings on the guitar I get a lot of relief and the curve seems consistent. When I tighten the rod, the neck straightens out but frets 1-4 dive backwards, it's behaving almost as if there's a hinge in the wood at around the 4th fret. Is it possible that the change in humidity would have introduced such an odd hump at around fret 4/5, and that it would cause this?

The frets are stainless steel, there is very little wear and the fret work is impeccable. I suspect a dressing is in order. I just feel really stumped by how this neck is behaving.
Author:  Barry Daniels [ Mon Sep 12, 2022 7:50 pm ]
Post subject:  Re: Strange truss rod situation
I worked on a neck that reacted strangely when under tension. It turned out to be a grain irregularity that caused the neck to twist when strings and truss rod were brought up to tension. The cure was to level the neck under simulated string tension. This guitar was the encouragement I needed for making a string simulation jig using Teeter's design.
Author:  bobgramann [ Mon Sep 12, 2022 7:54 pm ]
Post subject:  Re: Strange truss rod situation
If it has only recently changed environments, it might be worth letting it settle in the new one for a few weeks before doing anything major.
Author:  Chris Pile [ Mon Sep 12, 2022 9:20 pm ]
Post subject:  Re: Strange truss rod situation
Quote:
If it has only recently changed environments, it might be worth letting it settle in the new one for a few weeks before doing anything major.


Wise words from Bob, but I'm betting the some of the wood has gone bye-bye. Time will tell, and then - plane the fingerboard.
Author:  Hesh [ Tue Sep 13, 2022 2:00 am ]
Post subject:  Re: Strange truss rod situation
Yep let it hang for a week or two before you do anything and a fret dress is in order provided that you really cranked the rod and tried to completely straighten the neck with the rod first. It's a bit of an S curve and they usually go away if the rod has enough travel and impact. If you can't get it straight and I think you said that above indeed a fret dress is in order and it will be a bit of a tough one because of the stainless frets.

I hear ya on it's strange to see this on a Music Man. I have a very premium Strat type guitar that I bought last year with a roasted neck and stainless. The neck is moving every several days and I have to adjust the set-up near weekly and it lives in constant 45% RH 72F.... I'm not pleased and if you noticed I am not indicating the maker. But lousy necks can be found on anything, sadly.
Author:  Chris Pile [ Tue Sep 13, 2022 7:19 am ]
Post subject:  Re: Strange truss rod situation
Conor, one trick I've tried that works some of the time.... tighten the truss rod all the way, and then leave it for a day. Then loosen it all the way, and leave it for a day. Repeat several times until the kink relaxes (hopefully).
Author:  Lou Thier [ Thu Oct 20, 2022 5:58 pm ]
Post subject:  Re: Strange truss rod situation
since this is a music man, the neck is probably quartersawn. when using quartersawn if the grain isnt perfectly parallel to the side or is cut at a diagonal ( so the grain kinda runs from one corner to the opposite) the wood can develop a "hump" if the wood hasnt been properly aged or dried. this can happen in perfectly flatsawn wood as well. who knows though? if the instrument was purchased new, the end user should be able to obtain an RA and have music man look at it and see if it is something covered under warranty! good luck!
Author:  Conor_Searl [ Mon Nov 14, 2022 12:44 pm ]
Post subject:  Re: Strange truss rod situation
Lou Thier wrote:
since this is a music man, the neck is probably quartersawn. when using quartersawn if the grain isnt perfectly parallel to the side or is cut at a diagonal ( so the grain kinda runs from one corner to the opposite) the wood can develop a "hump" if the wood hasnt been properly aged or dried. this can happen in perfectly flatsawn wood as well. who knows though? if the instrument was purchased new, the end user should be able to obtain an RA and have music man look at it and see if it is something covered under warranty! good luck!


Thanks man, perhaps that was the reason. I hung the guitar for a few weeks, moving the truss rod back and forth twice a day, it removed some of the hump, but not all of it. I ended up dressing the frets, and have a happy customer.
Author:  Chris Pile [ Mon Nov 14, 2022 2:11 pm ]
Post subject:  Re: Strange truss rod situation
Patience wins the day!
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