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Truss rods layout for a 6-string neck

Paul_Gaita

Paul_Gaita

Commercial User
Mar 25, 2010
77
75
New Bern NC
Disclosures
Prairie Heart Customs LLC
#1
Hi everyone! I have my first order for a six string - 35 inch scale, 54mm (2.126") at the nut and 94mm (3.7") at the heel. I'm going to use two truss rods - I've seen that Ken Smith only uses one, and Bruce has mentioned he only uses one unless the neck is very wide (I would consider this a pretty wide neck). And the customer is pretty adamant about having two truss rods.

I have two questions for those who have done this before - Do you recommend routing for each truss rod following the profile of the neck or going parallel to the center line? How far apart would you space them?

The customer wants a relatively thin C shaped neck - around 21mm at the 1st fret so I'm concerned about carving.

The neck is a 5 piece - the center is quartersawn maple .75" - then quartersawn wenge on either side .25" - and the outsides are rift sawn maple glued with opposing grain.

Any suggestions or advice would be greatly appreciated - thanks!
 
#2
Not able to tell if it was better or not but I built my 6 with splayed rods (meaning not parallel). They did not follow the outer edge either as I divided the neck width so the rods were following paths similar to strings. Can’t see it in this picture but the rods are closer together at the nut. If I remember correctly I think I divided the neck into thirds at the nut and heel and followed those lines. With a thin neck I recommend adjustment at the heel and rods that are not too tall.
IMG_5645.jpeg
 
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#3
What kind of rod, DA? I wonder of you'd get the same effect using (2) carbon fiber rods either side of a single DA rod? I don't know how realistic it is in practice, but if somebody overtightens one of the rods, can that introduce twist? Or does the presence of two rods allow you to dial out twist? Rickenbacker finally switched over to a single DA rod after decades of two rods, which always seemed like overkill on a 4-string, and hogged out too much wood at the neck/headstock joint. I think Alembic is the only production builder still using two rods on a 4-string, but what are most companies using for a 6? The splayed rod idea seems sound intuitively, and the heel adjust, so you aren't crowding them in at the headstock. Seems like if they were close together, they woudn't do much. One of the resident Pros may be along shortly to cut through the mustard i just slathered all over this thread.
 
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#4
Yeah, two rods drastically increases the chances of misadjustment.

Remember, the rod is not there to provide stiffness. The rod is there to provide adjustability. If your concern is adequate stiffness, then instead look at woods and grain orientations that provide stiffness - which it sounds like you already have - quartersawn maple and wenge ought to be plenty stiff, unless you have defective pieces (I’m assuming you don’t).

If more stiffness is needed, then carbon rods are the usual approach. An alternative is a carbon tow backstrap embedded in epoxy. There are other threads here in the LC that go into detail about that.
 
#5
Gilmourisgod said:
What kind of rod, DA? I wonder of you'd get the same effect using (2) carbon fiber rods either side of a single DA rod? I don't know how realistic it is in practice, but if somebody overtightens one of the rods, can that introduce twist? Or does the presence of two rods allow you to dial out twist? Rickenbacker finally switched over to a single DA rod after decades of two rods, which always seemed like overkill on a 4-string, and hogged out too much wood at the neck/headstock joint. I think Alembic is the only production builder still using two rods on a 4-string, but what are most companies using for a 6? The splayed rod idea seems sound intuitively, and the heel adjust, so you aren't crowding them in at the headstock. Seems like if they were close together, they woudn't do much. One of the resident Pros may be along shortly to cut through the mustard i just slathered all over this thread.
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2 dual action flex strong rods - they’re relatively shallow - 9.5mm deep channels required. I personally think that with the way the neck woods are laid out, one rod would be enough, perhaps even without the carbon fiber stiffening rods. But the customer is set on 2, and I kind of understand wanting to have that option in case some twist does develop over time. I would really prefer adjustment at the headstock, for looks mostly. The body top wood will be a really nice piece of flamed spalted maple that I want to keep intact as much as possible.

I never understood two truss rods in 4 string necks. I get the theory - but it seems like overkill, especially in a well laminated multi piece neck.

The customer has been playing a sire m7 - which has two truss rods. I know most Ibanez 6s have two as well, as do fodera. I like the idea of splitting the neck into thirds and following the lines. I’ll have to play around with some layout ideas.
ctmullins said:
Yeah, two rods drastically increases the chances of misadjustment.

Remember, the rod is not there to provide stiffness. The rod is there to provide adjustability. If your concern is adequate stiffness, then instead look at woods and grain orientations that provide stiffness - which it sounds like you already have - quartersawn maple and wenge ought to be plenty stiff, unless you have defective pieces (I’m assuming you don’t).

If more stiffness is needed, then carbon rods are the usual approach. An alternative is a carbon tow backstrap embedded in epoxy. There are other threads here in the LC that go into detail about that.
Click to expand...
Yea I’m not necessarily concerned with stiffness of the neck. I think, if anything, 2 rods will make it slightly less stable since there will be more wood missing from the overall structure. I still think it’ll be plenty stable, my main concern is the spacing between the rods to allow for carving without getting too close to them.

I understand wanting the option to counteract any twist that might occur over the life of the instrument. I want to make sure the rods still function as they should while remaining as close to the centerline as possible.
 
#6
I've only adjusted one bass with two DADR truss rods and that was an Ibanez. The twin Ric rod style is a different beast. When reading up on the double rod adjustment process, the seasoned techs seem to adjust them together like they were a single rod, and that it doesn't tend to be an effective real-world practice to get different relief settings on different sides of a neck. These reports would lead me to probably focus more on keeping them close together so that I could keep the neck carve thin. From the builds I've watched here on TB that have employed two truss rods, they have been about 50/50 whether they are parallel or slightly tapered. :thumbsup:
 
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#7
Beej said:
I've only adjusted one bass with two DADR truss rods and that was an Ibanez. The twin Ric rod style is a different beast. When reading up on the double rod adjustment process, the seasoned techs seem to adjust them together like they were a single rod, and that it doesn't tend to be an effective real-world practice to get different relief settings on different sides of a neck. These reports would lead me to probably focus more on keeping them close together so that I could keep the neck carve thin. From the builds I've watched here on TB that have employed two truss rods, they have been about 50/50 whether they are parallel or slightly tapered. :thumbsup:
Click to expand...
I think I’m gonna try the slightly tapered approach, but keep them pretty close at the nut - closer than evenly dividing in thirds.
 
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#8
Paul_Gaita said:
I think I’m gonna try the slightly tapered approach, but keep them pretty close at the nut - closer than evenly dividing in thirds.
Click to expand...
I think I may have actually done the same at the nut. I have photos so I can check next time I’m at the computer. I had very shallow titanium rods to use in that neck. The two titanium weighed less then one steel rod which is why I chose to use them. Also that bass has a solid ebony neck through construction so I wanted two rods so I would have a chance to adjust the neck if needed. Remember a steel rod will be heavier then the wood removed to install it.
 
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#9
Slidlow said:
I think I may have actually done the same at the nut. I have photos so I can check next time I’m at the computer. I had very shallow titanium rods to use in that neck. The two titanium weighed less then one steel rod which is why I chose to use them. Also that bass has a solid ebony neck through construction so I wanted two rods so I would have a chance to adjust the neck if needed. Remember a steel rod will be heavier then the wood removed to install it.
Click to expand...
Do you remember the measurement? I think I’ll be able to get away with 9.5mm but I’d be interested in something titanium and more shallow for future builds.
 
#13
Here's what was an ibanez 6 string neck. showing twin truss rod spacing at the 2-1/8" nut, I used it for a 10 string. the rods are parallel same as Hamer and Dean used on their 8 and 12 string basses. All work very well. The Ibanez six string neck is VERY thin. I build all my 12 string basses with parallel rods.
AtWajaz.jpg
 
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#14
Slidlow said:
The ones I have are 9mm deep and 6 mm wide. I ordered them 630mm long. I got them from KTS in Japan but I do not know if they still produce them.
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Are they single action? Seems like they're still available but I can't find dual action. I think I'll be ok with 9.5mm depth, I was interested in the titanium because of the weight.
 
#15
What is the weight difference? I would think it would be minimal, especially when you consider that the weight is spread out almost the entire length of the neck. A gram saved near the headstock is worth much more than a gram saved near the sixteenth fret.
 
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#16
ctmullins said:
What is the weight difference? I would think it would be minimal, especially when you consider that the weight is spread out almost the entire length of the neck. A gram saved near the headstock is worth much more than a gram saved near the sixteenth fret.
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True - I’m probably overthinking this. I think the flex strong rods will be fine.
 
#17
Paul_Gaita said:
Are they single action? Seems like they're still available but I can't find dual action. I think I'll be ok with 9.5mm depth, I was interested in the titanium because of the weight.
Click to expand...
The ones I have are dual action. They had stopped making them and I was not sure if they had started again. The weight saving is great as two titanium weigh less then one steel.
 
#18
#19
Dadagoboi said:
Here's what was an ibanez 6 string neck. showing twin truss rod spacing at the 2-1/8" nut, I used it for a 10 string. the rods are parallel same as Hamer and Dean used on their 8 and 12 string basses. All work very well. The Ibanez six string neck is VERY thin. I build all my 12 string basses with parallel rods.
AtWajaz.jpg
Click to expand...
Parallel is great for production.
 

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