Hello all,
I'm trying to gather information on truss rod installation. Some of the questions that have been lingering in my head over the years :eyebrow: ....

I've seen wide neck basses, such as 6 and 7 stringers etc.., with dual and/ or single truss rods. Why do some six or seven stringers use single truss rods while others use dual truss rods???
What would be the benefits of using a dual truss rod setup, if there are any???

When I see a description for a four string which reads; "two way adjustable truss rod"; Does this mean...
a) An actual typo?
b) Two truss rods?
c) A single truss rod which can be adjusted at both ends (i.e. the neck joint and the headstock area)?
If it is "c", what would the benefits?

I've been looking around on the stewmac website but I can't find any specific answers, maybe somebody around here can point me in the right direction??? :D

2 truss rods allow you to adjust the bass and treble sides to get even relief across the neck, in theory. A lot of builders have gone to using 1 truss rod and gaphite stiffening strips to keep the neck straight. Others use very dense woods for their necks so they only need 1 truss rod on 6+ strings.

2-way truss rods bend both ways so you can adjust forward bow or back bow with the same rod. They have become quite standard in the industry.

I dont like the idea of dual rods since the neck will have to be thicker. With a single truss rod, it runs down the center of the neck and somewhat determines the "minimum thickness" of the neck since you must have X ammount of wood underneath it for support. If you have two truss rods, than the neck must be made thicker because you need this "minimum thickness" in two areas, not down the center.

I should point out the only reason I had "minimum thickness" in quotations is for coherency of the above statement.

For example, lets say we have a 3/8" deep truss rod, you should have an 1/8" of wood or so underneath it so we have a 1/2" thick neck (not counting fingerboard), right? Well if we have two rods now, the 1/2" is no in the center of the neck, its running underneath the truss rods, and unless you want a weird neck that has a big flat spot on the back or otherwise shaped strange, it must be thicker overall.


I hope someone can make sense out of what I just said :) I personally just use single rods with no graphite. They are very stiff. I may experiment with graphite in the future to see how I like it.

To answer your last question, it would serve no purpose to have truss rod adjustment on both ends.

Thats some cool Info mister DSB1, I was just asking this exact question not long ago. Is it worth having two rods on a six string? theres Ipe and Purpleheart in this neck (3/4" Ipe) both woods are known to be stiff as hell. and i like necks like Ibanez... so there you go. Im using one Rod I guess. what do you think?

Thats some cool Info mister DSB1, I was just asking this exact question not long ago. Is it worth having two rods on a six string? theres Ipe and Purpleheart in this neck (3/4" Ipe) both woods are known to be stiff as hell. and i like necks like Ibanez... so there you go. Im using one Rod I guess. what do you think?

I've made several six strings, all with one truss rod and no other reinforcement. They've been around for years, the necks are stiff and perfectly stable. I think that two truss rods have some merrit with basses with crazy amounts of strings, but thats not really what I like to build anyway:)

Some of the higher end Ibanez's I've played have great feeling, thin necks. I'd be confident using one rod, but the laminations must be good and the neck must otherwise be sound.

What kind of rod are you using? I've been using a modified version of the regular LMI ones on my instruments for years now. They are only 3/8" tall, versus some other rods that are a 1/2"...might not sound like a lot but you better beleive that it is.

Im using StewMac's Hot Rod, which is 11.10mm (almost half an inch) I do believe you its a lot, I want my neck to be about 20mm at the nut, with fingerboard, so it leaves about 3mm under the rod (1/8) should be ok as long as im very careful while shaping the neck !

What about stiffening bars? I don't seem to hear much about them. I've noticed with the classic Fender design, you had the truss rod with a stiffening bar on top of it, or at least that's what I've seen with the diagrams of the Fender neck design. I understand that other luthier's place two stiffening bars in the neck along with the truss rod, one on both sides of the truss rod. What is the protocol for this? What size stiffening bars do you use? How long do you cut them? How far do you install them from the truss rod, etc..etc..?? :confused:

Im using StewMac's Hot Rod, which is 11.10mm (almost half an inch) I do believe you its a lot, I want my neck to be about 20mm at the nut, with fingerboard, so it leaves about 3mm under the rod (1/8) should be ok as long as im very careful while shaping the neck !


Get yourself a safe-t planer. This allows you to safely and accurately level the back of the neck. Be very careful to keep the neck level on the table while doing this! Play it safe and build yourself a large flat table that you can bolt or clamp your your drill press.

The safe-t planer is also great for making thin laminates if you dont have a thickness sander.

Ahoy,
while we are on the topic... I've been readin Hiscock's book as well as Roger Siminoff's, both books suggest filling in the truss rod channels (after the rod has been installed) with fillets, small strips of maple. Both books are old, no need to say, nothing is mentioned about StewMac's Hot Rod. This is probably a question that has been answered numerous times before... anyways, do I glue in the Hot Rod? seeing its covered with tubing, it would pull the neck with it, or does it really just push on the fretboard. The fretboard doesn't risk cracking? From what i've read, I should glue only the tips of the rod... in this case it would create pressure on the fretboard.... hmmm. I would like to install it this week and I would (obviously) like to know exactly how to proceed in doing a proper job. Thank you all !
-Mario-

Ahoy,
while we are on the topic... I've been readin Hiscock's book as well as Roger Siminoff's, both books suggest filling in the truss rod channels (after the rod has been installed) with fillets, small strips of maple. Both books are old, no need to say, nothing is mentioned about StewMac's Hot Rod. This is probably a question that has been answered numerous times before... anyways, do I glue in the Hot Rod? seeing its covered with tubing, it would pull the neck with it, or does it really just push on the fretboard. The fretboard doesn't risk cracking? From what i've read, I should glue only the tips of the rod... in this case it would create pressure on the fretboard.... hmmm. I would like to install it this week and I would (obviously) like to know exactly how to proceed in doing a proper job. Thank you all !
-Mario-

The filler strip is for single action, rod style truss rods. This does not apply to the kind we are talking about. The pressure on the fingerboard will be fine. If the neck is suitably stiff you should never have to use much pressure from the truss rod. Always prepare wood joints with care.