Official Luthiers Forum!

Hi.

I am a total novice builder and I am relying on the wood-shop team at the high school where I teach.

Presently I am creating a replica of a Gibson L6 (very much like a Marauder) as my first build.

I am about to order a truss rod and I am totally stumped as to how the dual rod truss rod is installed or how it works.

From what I have seen online the rod is simply laid in the channel and the fretboard glued over the top. If the rod is not anchored to the neck anywhere, how does it have any effect on the neck tension? Furthermore, how does it function to curve the neck in both ways. I'm baffled by the operation of this rod.

It has been suggested that I go with this type of rod, but I have to know how it works before I can commit to buying one.

Any links, video or diagrams would be appreciated.

Thanks,

Jeff Canada

let me preface by saying that i am no pro, so dont take my word as gospel but in my opinion these rods are great. they are the simplest to install and work great.

here is how it works, as i am sure you have seen from photos, there are two rods that are anchored to each other, the upper rod is fixed and is a set length, the lower rod is threaded on both ends and is adjustable. when you turn the nut on the rod and thread it in you are making the bottom rod longer than the top rod, but sense they are anchored to each other the bottom rod cannot expand without compressing the upper rod. this forces both rods to go into an upward arch to compensate for the extra length of the bottom rod. the same thing happens when you turn the nut the other way but in reverse, you are compressing the lower rod, and stretching the upper rod.

this same action will occur weather the rod has been installed or not, it operates independent of the guitar so it does not need to be anchored.

_________________
~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

Thanks Peter. So far I am understanding how the two rods are attached and work together. My question is still this: if the truss rod is not anchored to the wood in any way, how is it affecting the tension of the neck?

Perhaps I need to just buy one and put it in and see for myself?

oh, ok. well obviously whenever you turn the nut its going to arch up or arch down. say its arching in an up bow when it does it the two end are pushing on the bottom of the channel and the center is bowing up and pushing on underside of the fretboard. in actuality it needs to not be anchored to function properly, if the end were anchored it would not be able to flex properly. as long as its a snug fit around the end blocks it wont slide around in the channel or anything, especially if its under tension.... does that help at all?

_________________
~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

Thanks again. If I'm getting the right picture here, the truss rod assembly is flush against the neck and the fretboard; the channel is cut so precisely that the rod sits completely snug against the wood in both directions, so that it can push against the neck wood or against the fretboard?

So, in correcting a neck with too much relief, the rod is adjusted so that it pushes against the fretboard (in the middle), thus bowing the neck back? And vice versa, pushing against the neck in the middle and pushing forward on the ends of the fretboard?

Am I getting the right picture here or am I way off? God help me on this one ...lol.

If this is the principal behind it, then it is relying on the strength of the glue joint between the neck and the fret board for full effect?

Jeff

yup, you got it, thats the basic principle behind em. and you are right you are relying heavily on the strength of the glue joint between the fretboard and the neck, but keep in mind that a good glue joint is actually stronger than the wood itself. if done right the wood next to the joint will break before it breaks at the seam and that would take a tremendous amount of force from the truss rod.

_________________
~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

That is true, the glue joint is stronger than the wood. I guess I'm finding hard to think of the rod as placing any upward pressure on the fretboard, whether in the middle or the ends.

Another question ... does the fretboard need to be a little thicker (and neck a little thinner) with the dual rod, or do we just stick with traditional specs?

Thanks again ...

traditional specs will work fine. and dont worry this will put all the force you'll need on the neck, they work great.

_________________
~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

Okay, I will add one to my order tomorrow.

Thanks a lot, I had been scratching my head over this one for a while. Without seeing one up close and placing it in some wood, it was hard to visualize what it was doing ... makes perfect sense now.

Shad,

Sorry if I confused your first and last names earlier.

Checked out your site and photos ... two thumbs up, man. I could only dream of building the creative and quality guitars you have made.

J

jeff, i am glad to help. and dont worry about the name thing, if i had known how personal of a forum this was when i joined it i would have just put down my name, so the mix up happens a lot.

and thanks a lot for the compliment i sincerely appreciate it and i am always glad to hear when people like my work, but on that note you should really check out some of the stuff that the other guys on this forum are doing. there are some really phenomenal luthiers that straight up put me to shame. keep us posted on your build, let us know how its going, and don't be afraid to ask any questions. and welcome to the forum by the way.

_________________
~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

Shad,

Watched a few of your youtube videos too. The tv interview was very well done.

I'm totally new to the forum, just joined yesterday, so I will certainly take the time to look around, meet some new people and see what they are building.

Best of luck with your builds.

J