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| Curious Neck Movement http://luthiersforum.com/forum/viewtopic.php?f=10101&t=44506 |
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| Author: | RusRob [ Thu Nov 06, 2014 1:19 am ] |
| Post subject: | Curious Neck Movement |
I finished my first build this past spring which is the 1800's styled Parlor as some of you may remember. Over the past 2 or 3 months I noticed it picked up a bit of string buzz. When I finished it I set it up like I normally do and it played very nice. i like very low action and for my first build I was quite pleased that it played and sounded much better than I expected. Yesterday I picked it up to play it and I noticed the 1st string had a pretty bad buzz at about the 3rd fret. So thinking it may need a truss rod adjustment I checked the relief with a straight edge and it was a bit high but not bad. So I loosened all the strings and pulled and taped them out of the way and used my short straight edge to check where the problem was. I found that there is a hump starting at the 3rd fret and ending about the 5th fret. I was very careful when I leveled the fretboard and the frets (which I have done countless times) so I know it was level when I finished the guitar and when I did the setup. I keep my house and shop at between 45 and 50% humidity all year long and the temp remains in the mid 70's all the time as i have central air as well as humidity control and de-humidifier. So i know this isn't from humidity or temp changes. It has been 6 months since I completed it and since this is my first build I am wondering if it is normal to have this kind of neck movement in a freshly built guitar? It was built from an LMI kit and the neck was pre-carved. I used HHG to glue the fretboard to the neck and left it clamped for a full 24 hours and there are no gaps showing between the FB and the neck. The frets are not pulling up and are all solidly seated. So before I re level the frets I wanted to see if anyone has had this kind of issue before. Thanks for any help you can give. |
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| Author: | uvh sam [ Thu Nov 06, 2014 6:09 am ] |
| Post subject: | Re: Curious Neck Movement |
Double action truss rod? I have seen those cause that type of hump when they have to force a lot of relief into the neck because the end of the rod is pushing directly against the fretboard. That's my guess anyway |
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| Author: | RusRob [ Thu Nov 06, 2014 10:03 am ] |
| Post subject: | Re: Curious Neck Movement |
Thanks for the suggestion Sam. Yes I did put in a double action truss rod. However I did cap it with wood and also installed it as far up to the headstock as I could. I actually think I installed it too far up because the Allen head cap just barely protrudes into the body and is pretty difficult to get the wrench to. They originally sent me a 12 fret truss rod which for obvious reasons would have only come up to the 2nd fret and would have caused an issue like this. And yes I did just double check to be sure I put the right one in since I kept the 12 fret rod (just because of your post). Could it be my problem is that the rod is too far forward? Edit: When I installed it I did check the rod before and after installing to make sure it was working correctly. And I remember when I put the strings on the neck had almost the perfect relief so very little adjustment was needed. After about a week of playing, it needed another adjustment but has been fine up until this... Thanks again, Bob |
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| Author: | RusRob [ Fri Nov 07, 2014 7:42 pm ] |
| Post subject: | Re: Curious Neck Movement |
Just as a follow up on this post: After discovering the hump in the #3, #4, and #5 frets, as I said I loosened the strings to check the problem and there was clearly a bit of a hump, nothing that couldn't be easily taken care of with a little fret dressing but I decided to take all the tension off of the truss rod and leave it for a day or so to think about it. That is when I started this thread to ask if anyone had seen anything like this before. Well I let it sit and wasn't in any rush to try to fix it. Late last night I sat down to look at it and to my surprise the hump was gone. The fretboard was perfect with just a touch of back bow just as it was when I first did it. So I left the truss rod with no tension on it and put the strings back in place and tuned it up. I then checked the relief and it was pretty much spot on. So the only thing I can think is when I first set it up I put some tension on the truss rod and over the last 6 months since it was built the neck settled in and created that small hump. It was mentioned in another thread that my problem was probably humidity but the humidity has not changed by more that 5% here in my office where I keep my guitars. Just to check I did a wet bulb test to check the accuracy of my hygrometers. My one digital which is non adjustable is still off by 7% and my others that are adjustable were recalibrated but the worst one was only off by 3%. I usually calibrate them a couple times in a year but had not done it so I was over due. But the humidity was not the issue and the only thing I can come up with is the neck just settled in. So all is good with my parlor and hopefully it will stay that way. Bob |
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| Author: | George L [ Fri Nov 07, 2014 8:08 pm ] |
| Post subject: | Re: Curious Neck Movement |
Bob, I'm glad to read that things are improved with your parlor guitar. Even though the humidity in your space was fine, perhaps the moisture content of the neck was not? If the neck had not fully acclimated before assembly, one could, over time, find symptoms attributable to humidity changes, without there being any dramatic variances in the actual space. I'm woefully lacking in diagnosis and repair experience, so this is really just me kind of thinking out loud. 
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| Author: | RusRob [ Fri Nov 07, 2014 9:19 pm ] |
| Post subject: | Re: Curious Neck Movement |
Thanks for the input George, I have plenty of diagnosis and repair experience but have never run into this before so any ideas into what it could be is knowledge to me. Since I am new to building there is a lot I don't know. You could have a point about not being acclimated. I had the kit for several months before I started building it and I kept everything in the box it was delivered in until I needed them. And come to think about it I had the box in my office against an outside wall. I finished it in May so it was sitting there through some chilly weather. As I said I keep my house and shop at about 74 degrees and the humidity runs between 40 and 50%. Being the outside walls are colder it could have raised the humidity in the box... So your idea could have merit. But either way it seems at this point everything is fine and there is no tension at all on the truss rod so I will keep an eye on it and see if anything changes. I had the chance to sell this parlor a couple of times but in both cases I said no because it is only my first and I want to see how it holds up to time. That is one of the reasons I am not jumping into building my next one. I have the plan and idea down of what I am going to build but I don't want to put a lot of effort and time into rushing into it only to find out I am doing something drastically wrong. So thanks for your input, It all helps. ![[:Y:]](./images/smilies/smiley20.gif "Thumbs Up") Cheers, Bob |
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| Author: | Haans [ Sat Nov 08, 2014 7:12 am ] |
| Post subject: | Re: Curious Neck Movement |
I set up my guitars with just enough tension on the T/R to keep it from rattling. The fingerboard should be in a backbow when tension is off the strings and the T/R should be essentially in neutral adjustment. This is why I put frets in after the instrument is finished and together. It allows me to straighten the fingerboard using a jig similar to the Stew Mac neck jig. The idea is NOT to have to use the T/R to offset the string tension. |
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