Necks without truss rods

[ardgedee]

A few companies were making basses without truss rods in the 60s. They were mostly the low-end ones. It's not hard to find stories about Tiescos unplayable because the action's half an inch off the neck at the 12th fret...

In the 80s, some luthiers were building carbon fiber necks without truss rods (Steinberger, Modulus, Status...). This time it wasn't about being cheap, it was because they were confident their necks would never move under the loads presented by bass strings.

Every one of the '80s pioneers of carbon fiber use adjustable truss rods in their current products, and there are probably good reasons why. But they've proved that a trussrod-less neck is feasible (plenty of examples still being played 40 years later), even if it's not commercially viable, so this got me wondering...

How would you build a neck without an adjustable truss rod? How do you ensure the neck wouldn't move, without making it chunkier? (using a lot of carbon fiber is one answer, but are there others?) How would you add relief to the fingerboard when you can't just sand it straight and let the interaction of string tension and truss rod set the action? How do you even anticipate how much relief to add? How would you ensure the string paths on a fretless are properly leveled when you have to account for relief as well? Are there other complications I'm missing?

 

[Roland GR 88]

I believe that the questions in your last paragraph have never been properly answered you haven’t missed anything.

 

[Lo-E]

I play an early Modulus BassStar with no truss rod and I can’t use my usual medium gauge strings on it but it sets up perfectly with lighter strings, so there’s a perfect example of it being feasible but not necessarily a good idea.

Speaking theoretically (because I’ve never built a neck and I wouldn’t build one without a truss rod), I would:

build a multi-lam neck

Pay close attention to grain orientation

Use very stiff woods

Utilize a carbon fiber backstrap à la @Bruce Johnson

Use a very dense, thick fingerboard

Possibly include Carbon fiber beams under the fingerboard (does that qualify as a truss rod?)

For fingerboard leveling I would either mock up a jig like Stew-Mac’s that emulates string tension or I would get the type of sanding beam that fits under the strings and level the board with the strings tuned down a half step so that the relief would bend into the neck when tuned up to pitch.

 

[MattZilla]

It’s addressed in a paragraph or two in Dan Erlewine’s book and is something I’ve thought about a lot but don’t feel like doing strongly enough to actually do it:

bullet/tombstone profile instead of mushroom/T profile frets.

Cut the fret slots at 0.080” wide and flat bottomed 0.100” deep at the center of the neck

Stainless steel stock, probably 318, something around 0.090x0.200”; mill batches of frets at widths of 0.0790”, 0.0791”, 0.0792”, 0.0793”, etc., drill a handful of small dimples into both sides of each fret for the wood to bite into a little.

Initial relief setup would probably take an actual half a day, do a quick & dirty levelling & crowning, then I’d want to let it settle for a month or two of heavy playing or rigged into a vibration fixture, and probably swap a few frets (possible all of them) to perfect the relief. Perfecting the relief would probably be at least an hour of swapping frets before going into the task of doing a good job levelling, crowning, and polishing.


Doing all of it with a manual mill would be an interesting way to avoid the real world for a few weeks. Doing it with a CNC would still be very time consuming.

It is something I’d like to do when I’ve got a full head of white hair. I really like the feel of fretless so much that I’ve experimented with 0.009” guitar strings glued on a defretted & filled neck as frets and felt that even smaller height but more massive frets would be really nice & cozy feeling.

Someday I’ll do one or two for myself, but I’d never try to push it as a legitimate product with my name on it to someone.

eta- IIRC, Erlewine said that the luthier he knew of who did the fret-relieved neck thing would do another checkup a year out and then it’d be kinda set for life. I’d want to use a really stable set of woods for the neck & board. I haven’t experienced a non-reinforced maple or mahogany neck be even in the parkinglot of the ballpark of being as stable through humidity & pressure changes as ovangkol+wenge or wenge+wenge necks.

I do think that if using normal CITES approved woods and normal electric bass guitar neck dimensions and wanting to do it without any adjustable truss rod, you’d want to go with three or four reeeeally stiff off the shelf reinforcement rods or even construct a triangulated truss to inlay into the neck and then simply carve relief into the fingerboard.

 

[T_Bone_TL]

Most uprights don't have truss rods, either historically or currently. They do have a lot more maple thickness and the necks are comparatively short, making the beam very stiff. Relief is carved into the board, AIUI.

I would guess that with a mass produced CF instrument the relief & string paths would be established via a master, and the mold would replicate that. Not too practical for a one-off. For CF with an applied board perhaps some cousin of a plek fixture would be used?

 

[ardgedee]

Possibly include Carbon fiber beams under the fingerboard (does that qualify as a truss rod?)

I'd consider those reinforcement bars rather than truss rods. My question was about adjustable truss rods, so I've edited the OP to clarify that.

 

[Lo-E]

Most uprights don't have truss rods, either historically or currently. They do have a lot more maple thickness and the necks are comparatively short, making the beam very stiff. Relief is carved into the board, AIUI.

This is correct and true of the entire viol family. The requirements are quite different, though, as actions tend to be higher on a bowed instrument (the string excursion can be pretty lively) so there’s a little more room for error than there would be on a fretted instrument or even on a fretless bass where the action might be quite low.

 

[Quills]

Making the neck easily removable would be helpful so that, if the worst should happen, you can do the case-equivalent form of angle correction (e.g. neck reset or bolt-on shim) fairly painlessly.

 

[Flying B]

I wonder what's the advantage of not having a truss rod? Aside from maybe the weight saving gain? I suppose if you live somewhere with wildly varying levels of humidity/ temperature and you're forever having to adjust it that could get annoying. I hardly ever touch mine.

 

[ardgedee]

I wonder what's the advantage of not having a truss rod? Aside from maybe the weight saving gain? I suppose if you live somewhere with wildly varying levels of humidity/ temperature and you're forever having to adjust it that could get annoying. I hardly ever touch mine.

For my part it's curiosity about something that used to be done and currently isn't. I have no intention of building a neck without one. It seems way too easy to get wrong, unless somebody's got a geniune surefire construction technique.

 

[Bruce Johnson]

Um....Yeah. I agree with most of what you guys are saying.

You can build a neck without a truss rod, if you really want to. You'd probably want to build it fairly stiff, adding some internal stiffeners like aluminum plates or carbon fiber TOW backstraps. And the process for surfacing the fingerboard and leveling the frets gets more complicated. You have to measure and/or guess how much the neck is going to flex under the tuning and strings that you intend to use on it. Then figure some way to preload the neck to something a little less than that. Surface or level it. Then string it up and hope it comes out to the right amount of relief. A lot of guesswork and trial and error.

Or, you carve the surface into the curved relief shape, guessing how much the neck will bend when you apply the string load. Planing a curved shape, while keeping the string paths true; no lumps or dips. It's tricky.

And that's how you surface the fingerboard on a Double Bass. Planing in the relief curve, while keeping the string paths True, and shaping the cross-wise radius. All while guessing how much the neck is going to flex under string load. It takes some serious practice and skill.

We electric bass folks like truss rods to avoid all that. Tighten the truss rod up halfway, trim the fingerboard to flat. Which is much easier. Then pull up the strings and see how the neck curves up under load. Fine tune the truss rod up or down a little bit to get the relief right where we want it.

 

[MultiScaleMale]

I had a Steinberger without a truss rod early on and I thought I broke it, warped the neck by the way I stored it resting up against the wall in my closet. Found out a few years later that is “relief” and it’s supposed to be there. Heh.

 

[petermwright]

Interesting topic. I’ve never owned a bass with a carbon fibre neck, but am intrigued by the idea of a neck that doesn’t move with the seasons, and have wondered how much relief you get with a carbon fibre neck, and if you can adjust it.

 

[abarson]

I believe Wishbasses do not come with a truss rod, unless it's a custom order. His builds are typically neck through with a denser wood in the center.

 

[Reedt2000]

I was working for a Peavey dealer when they bought Composite Acoustics (CA). The rep brought a bunch of instruments in, none of which had truss rods (these are carbon fiber if you're not familiar). None of them ever developed an issue. Some hung in the shop for quite a while, one the owner of the shop bought for himself and it was fine for the 3 years I still worked there afterwards. The rep told a story of a new England owner who left theirs in a boat house all winter and it was perfectly playable when he went out in the spring and realized it was out there. I don't know how they address relief, I'd guess it's built in to the molds they use? There were no basses as part of those offerings, but the guitars had really flat fretboard radiuses.

 

[Maestro29]

I would never trust it. Rick Kelly at Carmine St Guitars in NYC makes his Bowery/Chelsea guitars and basses without rods. They’re made with 120 year old reclaimed wood from buildings in NY. G.E. Smith has a guitar and a bass, says he doesn’t worry about it because the wood is so old and the necks are gigantic. Wishbass famously makes basses without truss rods, claims it’s not necessary as the necks are so big. Bass Player magazine did a review a while back where the neck went into an unplayable backbow when the humidity raised during a rainstorm. Wishnevsky’s advice to them was to shim a couple business cards under the bridge. My friend Robert played a rod-less Modulus in the early 90’s that got wrecked when he went on a road trip during the summer with no air conditioning in the car. I will say that my Spector hasn’t needed a truss rod adjustment in a few years, most stable neck I’ve ever encountered. With that said I feel safer knowing I have a truss rod in there just in case.

 

[rudy4444]

A few companies were making basses without truss rods in the 60s. They were mostly the low-end ones. It's not hard to find stories about Tiescos unplayable because the action's half an inch off the neck at the 12th fret...

In the 80s, some luthiers were building carbon fiber necks without truss rods (Steinberger, Modulus, Status...). This time it wasn't about being cheap, it was because they were confident their necks would never move under the loads presented by bass strings.

Every one of the '80s pioneers of carbon fiber use adjustable truss rods in their current products, and there are probably good reasons why. But they've proved that a trussrod-less neck is feasible (plenty of examples still being played 40 years later), even if it's not commercially viable, so this got me wondering...

How would you build a neck without an adjustable truss rod?

Construct your neck so it has the desired relief to begin with, or will attain that with a predictable string load on it.

How do you ensure the neck wouldn't move, without making it chunkier? (using a lot of carbon fiber is one answer, but are there others?)

Replace a portion of the neck shaft with a much stronger material.

How would you add relief to the fingerboard when you can't just sand it straight and let the interaction of string tension and truss rod set the action?

If you design and construct your neck correctly you can predict what will happen under string tension.

How do you even anticipate how much relief to add?

Develop a construction methodology that uses predictable materials and develop a standardized neck for YOUR instruments.

How would you ensure the string paths on a fretless are properly leveled when you have to account for relief as well?

Ditto last answer.

Are there other complications I'm missing?

Do it and you'll quickly figure out what you've missed.

I've built a few basses using some of those ideas and they worked for the most part. For the bass necks I added a 3/8" wide channel to the neck, tapering from 1/2" to 3/4" at the heel. I added a bar of 2024-T4 aluminum, cut 3/8" to 5/8" tall to the channel and capped the top with filler wood. The top of the wood filler strip was leveled to the neck surface so the fret board was glued to this flat and true surface.

It worked fine, and medium strings induced a little deflection that was close to what I would have put in as relief if there would have been a way to adjust it.

The bottom line is most players don't want to be limited in string choice and many want the option of decreasing or increasing relief. For that reason manufacturers have chosen to go with the adjustable rod option.

Irving Sloane, author of early books on instrument construction, installed a steel rod in his necks and butted the ends tightly to steel cross sections, claiming that if the neck should ever try to bow it would need to compress the steel rod, which would not happen in his opinion.

 

[bassliner50]

Absurd. Think of a human or any mammal without a spine.

 

[brianrost]

Every one of the '80s pioneers of carbon fiber use adjustable truss rods in their current products, and there are probably good reasons why.

The NS Design necks are not carbon fiber, they are wood with a carbon fiber core. There’s a big difference.

How about fixed truss rods? The original Danelectros had two steel bars in the neck. It’s probably why you never see one with a neck issue. Are the reissues the same?

 

[smart51]

The problem with gaining relief over time is a matter of creep not stiffness. Find a material with low creep to stop it happening.

How would I carve relief into the fretboard? Clamp it into a fixture that put a bit of back bow in it and carve it flat. When you unclamp it, it will have relief.