Bass without a truss rod

[EricF]

Originally Posted by Joey.Ogden

And no I'm not being dense... I'm being stubborn.

In that case, why did you bother to ask for advice on TB?

You seem to have everything figured out already, and despite the advice of many to use a truss rod and give your work of art its best chance for decent playability, you stand your ground on going without a truss rod. I'm not being rude, I'm just curious.

I hope your project is a success, and it's everything you hope for.

[cybersnyder]

Originally Posted by KFrost2008

99.99 or anything with infinitely repeating nine's isn't a real number fyi.

Except he wrote four nines, not a infinitely repeating list of nines. Even if he wrote an infinite list of nines, it would still be a "real" number. 99.99% is, in fact, a real number. It is also a rational number since it can be expressed as a ration of two intergers, 9999/10000.

[richnota]

Originally Posted by Joey.Ogden

Okay, so you dont think it's a good idea... but let's just say hypothetically for some reason a truss rod was unattainable. Would a 1.5" thick neck, on a short-scale bass, with a single cutaway body, and those woods, work? Just in theory. Would some other wood be more suited to the task?

You could pre-stress the action of the neck specific to the strings you'll use...my Wendler was designed this way...but my hunch is that is actually harder to do than build with a truss rod.

Anyhow, adjustable action is essential to a good bass. Don't cut corners here.

[BillyRay]

Stewmac sells non adjustable truss rod if memory serves. Or try to get your hands on carbon strips if you really want to go without a trussrod. It'll be better in the long run than a non adjustable aluminium rod.

[bassobsessed]

Playing Devil's advocate here: I've often felt that truss rods may compromise tone. Some of my favorite tones come from 50s Kay electric basses with no truss rods - however they are known to warp... Mahogany is known to be dimensionally more stable and hence less prone to warp than maple, although it is more prone to breakage (like Gibson headstocks)

[ChuckLarry]

Joey, the woods you are describing are strong and dense, but that doesn't mean they'll glue up nicely. It might seem you're on track with multiple thin pieces of stock for a "plywood" like build that adds strength, but don't forget that a good portion of the strength of laminate composite woods comes from the grains being perpendicular with each new level. You won't have that option on a neck unless you are cutting these strips out of some really large sheets of wood. Knowing that and how many blades/cutters/shapers you'll go through working the wood, I can't imagine shipping on a truss rod is a real issue here. In any event, unless they are grained perpendicular, it won't be as strong as you're hoping for.

If you are going to use aluminum bar or rod, there's no need to use multiple woods unless you simply want to do so for aesthetic purposes. I wouldn't use multiple rods either, however, just one rod or flat bar. As the wood moves (and it will), the multiple, separated rods will induce cracking much like unconnected rebar in concrete after severe settling. It works great as long as everything is stationary, but multiple rods that aren't connected will pull away from each other with movement, and since they're stronger than the surrounding structure, they actually help tear it apart. That's why you see rebar in grids with wiring attaching everything. When movement of the structure is unavoidable, it helps all the bar to move in the same direction to avoid structural failure.

[Jjango]

Originally Posted by Joey.Ogden

So I've decided to do the bass without a truss rod, BUT as a failsafe I'm going to build a number of aluminum tubes into the neck, running the full length. Currently I'm thinking two or three. These should make up a high enough percentage of neck volume that the warping wood won't be able to overcome them... Thus virtually eliminating the chances of the neck warping on me. How's that seem? Basically it'll be a truss rod without the adjustableness. And cost me absotively nothing.

Joey, watch this video – the part that might interest you starts about a minute and a half in:

http://www.youtube.com/watch?v=ZieGGECiQNs

(I'd still use a truss rod if I were you, though)

[Joey.Ogden]

Yay!

By the way, the last couple answers were more what I was looking for... not whether I should get a truss rod or not, but how I might manage without one. So thanks!

And I was originally going to lay the sheets in the "ply" at a 5-10 degree angle to each other, which seems to me like it might take lateral stress better... but that's just me guessing.

However, since conceding to the bar, I've decided to make the neck solid hard maple, and implant the rod into it.

Just oine more question before I start; I have a peice of 3/8" Mild steel rod, and a peice of aluminum tube, both of which will fit in the neck. My figgerin' says that either one would basically act like a truss rod, just not adjustible.

So ignore all previous questions and answer me these:

1) Is it better to go stronger (steel) or lighter (aluminum)?

2) How deep should the rod be into the neck (adjacent to the fingerboard, or near the handward side, etc.)

Thankee

[LarryO]

if you make bows why don't you design a radically new concept in neck design? Use the pulley system in compound bows to relieve the stress from the neck wood.........or just design a neck that would allow the bass player to shoot the drunkard of his choice with an arrow without missing a beat.

[cybersnyder]

You are a stubborn one...

[ChuckLarry]

.........or just design a neck that would allow the bass player to shoot the drunkard of his choice with an arrow without missing a beat.

Funny!

The aluminum, provided it is thick enough, should be fine. Just make sure it's thick enough. Steel is quite a bit stronger so you can use a thinner bar or lower diameter rod to get the needed strength and it won't weigh a whole lot more.

If you want to keep it interesting, use brass flat bar and take it all the way up to bottom of the nut slot (this may require a taller, self machined nut). In this case, the nut would sit on the brass in the middle and sit on the neck wood at each side. You'll get better strength than aluminum and sustain/resonance won't be an issue.

If you really want to go nuts and don't mind higher action, get a 1/8" thick brass flat bar about the width of the bridge mounts and run it from the nut to the bridge, tapering it down with a dremel tool as it moves up the neck. You would need to route a straight channel and move your jig slightly offset as the width increases at the bridge end. In this case, you would use a thin laminate top over the routed channel on the body as you would use the fingerboard over the neck. Drill holes for your bridge and go through the brass plate, thread the holes in the brass plate with a tap and die, then flat head "bolt" the bridge to the brass flat bar seated in the bass. You won't be able to route pickup channels as the brass plate will be in the way, so you'll need a top mount low depth pickup(s) and use some low pot values to cut the brightness. OR, you could make a slightly graded router template and route the channel deeper as the brass flat bar moves from the nut into the body, thereby allowing you to keep the brass lower into the body wood at the bridge end and still route for a bridge pickup slot (you would need to replace the displaced material here with wood). In either case, the bridge will be anchored to the flat bar via the flat head bolts (which will look just like screws) and the nut will be touching it also.

Why do this? You'll be able to hit an open note on Tuesday morning, set the bass down and still hear it ringing on Wednesday night.

[JazzBass Love]

Originally Posted by cybersnyder

Except he wrote four nines, not a infinitely repeating list of nines. Even if he wrote an infinite list of nines, it would still be a "real" number. 99.99% is, in fact, a real number. It is also a rational number since it can be expressed as a ration of two intergers, 9999/10000.

I'm glad I wasn't the only one to read that statement and have an issue with it. I hate to beat a dead horse, but a number is not real is if it can be written as a+bi (where a and b are real numbers, b is not zero, and i is the square root of -1). Ok, maybe that's not entirely true. In more abstract mathematics, it can represent geometries, algebraic structure, and a whole slew of other interpretations and uses. Anyhow, 99.99% happens to be real by all mathematical definitions that I am aware of.

Sorry for letting the nerd out, but after working for years to earn degrees in electrical engineering and mathematics seeing a foolish math statement is almost as big of a pet-peeve as hearing a guitarist say "bass is easier because it has fewer strings".

Anyhow, back to the topic on hand. I wish you the best of luck with your build project. The only instruments I've seen work "well" without a truss rod are extremely short scale (ukeleles, mandolins, etc). Personally, I'd recommend using a truss rod, but using a support rod should work to an extent.

[Jjango]

Originally Posted by ChuckLarry

If you really want to go nuts and don't mind higher action, get a 1/8" thick brass flat bar about the width of the bridge mounts and run it from the nut to the bridge, tapering it down with a dremel tool as it moves up the neck. You would need to route a straight channel and move your jig slightly offset as the width increases at the bridge end. In this case, you would use a thin laminate top over the routed channel on the body as you would use the fingerboard over the neck. Drill holes for your bridge and go through the brass plate, thread the holes in the brass plate with a tap and die, then flat head "bolt" the bridge to the brass flat bar seated in the bass. You won't be able to route pickup channels as the brass plate will be in the way, so you'll need a top mount low depth pickup(s) and use some low pot values to cut the brightness. OR, you could make a slightly graded router template and route the channel deeper as the brass flat bar moves from the nut into the body, thereby allowing you to keep the brass lower into the body wood at the bridge end and still route for a bridge pickup slot (you would need to replace the displaced material here with wood). In either case, the bridge will be anchored to the flat bar via the flat head bolts (which will look just like screws) and the nut will be touching it also.

Why do this? You'll be able to hit an open note on Tuesday morning, set the bass down and still hear it ringing on Wednesday night.

That idea sounds quite a bit like this thing:

http://www.skylabdigital.com/inst/i01.htm

[lowtide]

I built a bass without a truss rod that remains true at least 10 years after building and playing. I had a single bed I had from the time I was a kid, which was about 50 years ago, so the maple was good and seasoned. The entire body is built from this maple and the neck is tapered on the sides only. the shape is like a 2 x 3 with only slightly rounded edges for comfort. actual dimensions are 3/4" thick with the nut width of 1-1/2" and width at the pocket of 2-1/4" I think. I capped it with a 1/4" length of god knows what hardwood stock I also had lying around for years so the total thickness is only an inch. I'm really amazed that it didn't twist at all but it still remains true, deadspot free, and buzz free. I wouldn't sell this bass for anything it has so much sentimental value and great tone. The only negative I can say right off the bat is the bass weighs about 15 pounds~!

[Lorenzini]

Dude, that's awesome. A bed bass.

Originally Posted by lowtide

I built a bass without a truss rod that remains true at least 10 years after building and playing. I had a single bed I had from the time I was a kid, which was about 50 years ago, so the maple was good and seasoned. The entire body is built from this maple and the neck is tapered on the sides only. the shape is like a 2 x 3 with only slightly rounded edges for comfort. actual dimensions are 3/4" thick with the nut width of 1-1/2" and width at the pocket of 2-1/4" I think. I capped it with a 1/4" length of god knows what hardwood stock I also had lying around for years so the total thickness is only an inch. I'm really amazed that it didn't twist at all but it still remains true, deadspot free, and buzz free. I wouldn't sell this bass for anything it has so much sentimental value and great tone. The only negative I can say right off the bat is the bass weighs about 15 pounds~!

[Madcity Fats]

Originally Posted by LarryO

...or just design a neck that would allow the bass player to shoot the drunkard of his choice with an arrow without missing a beat.

And then sign me up for one of those bad boys.

[alder]

In my experience, a bass needs an adjustable truss rod, while a guitar is actually better with a fixed truss rod. But both need some sort of metal support.

The reason for this is simple: wood creeps under stress. Over time, the string tension will in most cases pull the neck out of true. Wood can also warp and twist as it ages, even under no stress at all. A wood guitar neck with no other support is almost certain to go bad over time, although that's not to say there can't be rare exceptions.

The strings on a guitar are thin and the distance that they vibrate is small enough that a guitar neck can be set up to be dead straight and play just fine. In fact, this is how most of them are set up. The best way to build and maintain this condition is to set a pair of steel bars or an aluminum box tube into the neck. It will never twist, never warp, never bend, and never require adjusting. Ever. The esteemed Martin company knew this from the beginning.

I have several Danelectros from 50 years ago that were built like this, and the necks are perfect. How many 50-year-old Gibsons can make that claim? The only adjusting a fixed-rod neck may ever need is a little shimming in the neck pocket to correct for bridge height.

Of course, with a set- or through- neck, this is impossible. So instead, the manufacturer installs an adjustable truss rod as the only possible correction for set angle and bridge height. But that is not what a truss rod is for, and it does not work well for this. When used to compensate for a bad set-neck, the truss rod will only give you different degrees of crooked and lousy, and a guitar that will never play well.

So if the only use of an adjustable truss rod on a guitar is to keep the neck straight, then why not dispense with the adjustment and use a fixed setup that is guaranteed to last forever? One word: marketing. Just try selling a fixed truss rod today - everyone knows adjustable is better. Or they think they know, anyway. A fixed truss rod would be looked upon as cheap. No one would buy it. Marketing.

Fender installed adjustable truss rods in bolt-on necks in the beginning because that was the accepted practice on some acoustic guitars, and Leo Fender really didn't know what he was doing. He was an electronics technician, not a luthier nor a mechanical engineer. That is not to take anything away from the genius, innovation, and beauty of his designs.

Now a bass is a completely different animal from a guitar. The strings are long and thick, and the distance they vibrate is significant. A dead-straight neck on a bass will buzz unacceptably or even choke out unless the action is set very high so the strings will clear the frets at every position when played.

To get a low action, a bass neck needs to be set up with a slight amount of forward bow to allow for the vibration of the strings. How much is a tricky question that will be different for every instrument and every player. Setting up a bass is an art, and there is simply no way a fixed truss rod would work. And trying to build a suitable curve into a fixed truss rod would be all but impossible.

So the bass is cursed to use an adjustable truss rod, with all of the drawbacks that implies, and the situation is actually aggravated by the greater length and greater stresses of a bass over a guitar. Change strings - adjust the truss rod. Summer - adjust the truss rod. Winter - adjust the truss rod. What fun. If you have any kind of feel for the instrument, you could spend forever fiddling with the damn truss rod. Or rods - my Ric has two !!!

But getting back to the original question, you need a truss rod. Any neck you build without one is almost certain to fail over time.

A long-scale bass can get along with a single-acting rod, as the string tension will naturally pull the neck forward, and you will only need to pull it back. A short-scale bass can better use a double-acting truss rod, as the string tension may not be enough to pull the neck into the proper bow by itself.

Well, I've said quite a bit, now let's hear from the trolls.

================================================== =======

I thought about it some more, and some old mechanical engineering memories came back to me. ( Being an engineer is a curse you can never quite escape from. ) The bending of the neck induced by string tension is known as "Mode 1", as illustrated in the image below:



The neck is effectively a beam, fixed at one end, and deflected at the other by the very small perpendicular force at the nut induced by the string tension being slightly offset from the center.

The effect of an internal truss rod is more like "Mode 2" - fixed at both ends and deflected in the middle, something like as illustrated in the next figure:



Nifty animations courtesy of Wikipedia.

In actuality, the truss rod is probably not pure Mode 2 bending, depending on how well fixed the one end is in the heel of the neck, but I'd guess that any such effect is too small to matter.

Therefore, an adjustable truss rod attempts to correct one mode, or shape, of bending, with a completely different one. In theory, the result should not be a straight line, but a compound curve that combines aspects of both bends. In practice though, it works fairly well, the remaining squiggles being small enough to not affect the play of the instrument. This is probably due to the smallness of the forces involved compared to the strength of the neck itself, and the smallness of the resulting deflections compared to the length of the neck. For a long scale bass, the perpendicular force is less than 2% of the total string tension, or 2-3 pounds; for a guitar that should be considerably less.

This is also why you want to use the strongest possible material for the neck - and Rock Maple is not called that for no reason. Hard maple has one of the highest bending strengths of any wood, ~1.8 Mpsi or more, about 30% higher than mahogany. Fender's earliest Telecaster experiments used soft pine (~1.2Mpsi) which pretzel-ed right up, as do many of Gibson's mahogany necks to this day ( if they don't snap off outright, but that's more a matter of bad design. ) Oak would also appear to be a good neck material, but it is dreadfully heavy and awful to work with, and except for Brian May's original 'Red Special' I can't think of any guitar with an oak neck. Poplar, a la Danelectro, is also not a particularly good neck material, but with 2 steel bars arranged as an A-frame solidly anchored in the heel and extending almost up to the nut, it doesn't matter. Most of the various "rosewoods" that are used as fingerboards are also quite strong and contribute significantly to the structure of a guitar neck, as does a maple fingerboard. ( ref )

The 2 different bending modes involved also explain why adjusting the truss rod is such a poor correction for a badly-set neck. The result of correcting the neck angle with the truss rod is the introduction of multiple short bends or warps, each of which will result in a "dead spot", usually just one or two. Sometimes these can be compensated for a particular set up with some skillful fret filing, but the instrument will basically always be a dog. Another solution is to mount flatwound strings, which are naturally much less buzzy than roundwounds and therefore more tolerant of dead spots.

Getting back to what I said earlier, a guitar can avoid all of this nonsense by simply having a fixed truss rod that does not bend to any noticeable degree at all, but that's really not an ideal solution for a bass.

Now I've said a real lot.

[wmheilma]

Check out Stewart McDonald. This is a good one:
http://www.stewmac.com/shop/Truss_ro...russ_Rods.html

[ggvicviper]

Originally Posted by alder

In my experience, a bass needs an adjustable truss rod, while a guitar is actually better with a fixed truss rod. But both need some sort of metal support.

The reason for this is simple: wood creeps under stress. Over time, the string tension will in most cases pull the neck out of true. Wood can also warp and twist as it ages. A guitar neck with no support at all is almost certain to go bad over time, although that's not to say there can't be rare exceptions.

The strings on a guitar are thin and the distance that they vibrate is small enough that a guitar neck can be set up to be dead straight and play just fine. In fact, this is how most of them are set up. The best way to build and maintain this condition is to set a pair of steel bars or an aluminum box tube into the neck. It will never twist, never warp, never bend, and never require adjusting. Ever. The esteemed Martin company knew this from the beginning.

I have several Danelectros from 50 years ago that were built like this, and the necks are perfect. How many 50-year-old Gibsons can make that claim? The only adjusting a fixed-rod neck may ever need is a little shimming in the neck pocket to correct for bridge height.

Of course, with a set- or through- neck, this is impossible. So instead, the manufacturer installs an adjustable truss rod as the only possible correction for set angle and bridge height. But that is not what a truss rod is for, and it does not work well for this. When used to compensate for a bad set-neck, the truss rod will only give you different degrees of crooked and lousy, and a guitar that will never play well.

So if the only use of an adjustable truss rod on a guitar is to keep the neck straight, then why not dispense with the adjustment and use a fixed setup that is guaranteed to last forever? One word: marketing. Just try selling a fixed truss rod today - everyone knows adjustable is better. Or they think they know, anyway. A fixed truss rod would be looked upon as cheap. No one would buy it. Marketing.

Fender installed adjustable truss rods in bolt-on necks in the beginning because that was the accepted practice on some acoustic guitars, and Leo Fender really didn't know what he was doing. He was an electronics technician, not a luthier nor a mechanical engineer. That is not to take anything away from the genius, innovation, and beauty of his designs.

Now a bass is a completely different animal from a guitar. The strings are long and thick, and the distance they vibrate is significant. A dead-straight neck on a bass will buzz unacceptably or even choke out unless the action is set very high so the strings will clear the frets at every position when played.

To get a low action, a bass neck needs to be set up with a slight amount of forward bow to allow for the vibration of the strings. How much is a tricky question that will be different for every instrument and every player. Setting up a bass is an art, and there is simply no way a fixed truss rod would work. And trying to build a suitable curve into a fixed truss rod would be all but impossible.

So the bass is cursed to use an adjustable truss rod, with all of the drawbacks that implies, and the situation is actually aggravated by the greater length and greater stresses of a bass over a guitar. Change strings - adjust the truss rod. Summer - adjust the truss rod. Winter - adjust the truss rod. What fun. If you have any kind of feel for the instrument, you could spend forever fiddling with the damn truss rod. Or rods - my Ric has two !!!

But getting back to the original question, you need a truss rod. Any neck you build without one is almost certain to fail over time.

A long-scale bass can get along with a single-acting rod, as the string tension will naturally pull the neck forward, and you will only need to pull it back. A short-scale bass can better use a double-acting truss rod, as the string tension may not be enough to pull the neck into the proper bow by itself.

Well, I've said quite a bit, now let's hear from the trolls.

Well said.

[bootsox]

It's always possible to go without a truss rod, but it's generally easier to just install one.

If you go without, make the neck 1-1.5 inches thick with little or no taper and out of a stable wood like mahogany, and embed a flat metal bar in it that extends the length of the bass