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Banjo Set Up: The “Hot” Rods”

[fa icon="calendar"] Apr 15, 2016 11:07:20 AM / by Barry Hunn

Inherent in the construction of banjos are certain parts that help address the needs of banjo set up. Among these are what we will call your “hot rods” - the coordinator rods and the truss rods.  But what does all this mean to you, the player, when it comes to banjo set up?

We get a lot of questions from our beginner banjo customers about making adjustments on their banjos and these two particular parts of the banjo are sometimes regarded with fear and apprehension. This “hot rod” topic is complicated by myth and misunderstanding commonly borrowed from the world of guitars by both players and technicians.

The first thing we want to know is what each of these rods do, the reason that they exist, and then how they work together so you can do a proper banjo set up.

Truss Rods

The truss rod is usually some sort of steel threaded rod that is embedded in a fretted instrument neck beneath the fingerboard. There are adjustable truss rods that offer “adjustment” to the amount of curvature in the neck and there are truss rods that are a stiff, solid material that are not adjustable.

The first myth regards the use of the truss rod. Folks believe you use it to “prevent the neck from warping” because of the tension of the strings. Well… Yes, sort of, but not exactly.

The Effects of Mother Nature:

Traditionally, banjo and guitar necks have been made of woods like, maple, mahogany, walnut and other various hardwoods. Also traditionally, some have had fingerboards made of rosewood or ebony that is glued to the playing surface of the neck.

Woodworkers throughout history have learned that gluing two different species of wood together, depending on the shape, thickness, size etc., can be subject to issues of “natural movement of the woods.” In other words, when we glue an ebony fingerboard to a maple neck, the ebony will expand and contract completely differently than the maple. It is this combining of two completely different materials that both have their own expansion and contraction properties that causes “warping” or twisting in banjo and guitar necks.

String Tension:

The intensity of steel string tension can exacerbate and exaggerate the movement of these two woods but depending on how many strings there are and how thick or stiff they are, the string tension itself is not the whole story.

Truss Rod Effect:

Having said that, this is where a fixed rigid bar or a threaded steel rod can help equalize the pressure of the expansion and contraction of the combined pieces of two different species of wood… Particularly in something long and slender like a banjo neck or a steel string guitar neck.

Built In Compatibility:

Deering’s Goodtime banjos have necks made of hard rock maple and the frets are mounted directly into the rock maple neck without a separate fingerboard so there is no need for a truss rod. The proper curvature for the neck is built into the neck from the start. This is one reason we recommend the use of light gauge strings for the goodtime banjo because the proper curvature was achieved by the known tension of the light gauge strings that we use relative to the amount of curve needed to keep the banjo fretting as easy as possible.s

Deering’s new Artisan Goodtime banjos have a rock maple neck and a separate Midnight Maple™ Fingerboard. Because these necks have the same wood in them as the fingerboard, the expansion and contraction characteristics of the neck and the fingerboard are the same. So again, there is no need for a truss rod because there are no conflicting forces that arise from two different species of wood and the proper curvature can be built into the neck during construction.

These techniques are not unique to Deering as there have been guitar makers as long ago as the 1960s that made maple necks with maple fingerboards and maple necks with no separate fingerboard and many of these guitars have achieved world-wide collector status and are still played today.

The second myth of a banjo or guitar neck is “It should be flat”. This is completely false.

  • When a banjo string or guitar string vibrates, it moves or oscillates very little at the ends of the vibrating length of the string and moves much more in the middle of the string’s vibrating length. (The vibrating length is the distance between fingerboard edge of the nut and the face of the bridge that faces the fingerboard.)
  • On a five string banjo with the 26 ¼ inch scale length the string moves or oscillates the least right next to the bridge and right next to the nut. It moves or oscillates the most over the 12th fret. The 12th fret is the center of the strings vibrating length.
  • The banjo that frets the easiest is the one where the string just clears all of the frets when it vibrates or oscillates. Because the oscillation or movement of the string is small at the end and bigger in the middle, trying to keep the string close to the fret means the fretboard must follow the curve of the oscillating string without touching it. The vibrating string is kind of a skinny banana shape when it’s vibrating; thin on the ends and thick in the middle. This is why all fretted instruments have strings that are very close to the frets where the nut is and the strings get higher or further from the fretboard the closer they get to the body.
  • If you have a fingerboard (neck) that is completely flat with no curvature, you will either have to raise the string height extremely high above the fingerboard and the frets so that the vibrating strings don’t hit the frets, or, you will have to play so softly to prevent the oscillating movement of the string from hitting the frets that you will likely be creating very, very little sound if any.

The properly installed truss rod that is “adjustable” does allow the player to “contour the curve of the neck” so the strings can be plucked and they will not touch frets on the fingerboard.

A third myth that comes from the world of guitars is that “the truss rod is how you adjust the action, or playability of your instrument.” This is not the whole story.

  • The curvature of the neck can be changed slightly to account for players with a very heavy attack or those with a very light attack. The effect of these changes is definitely real, but they are only part of the equation and more often than not these changes are extremely subtle.
  • The angle at which the neck of the banjo is mounted to the body is the most prominent factor to adjust a banjo’s playability, or action. (It’s the same on a guitar; both electric and acoustic). The banjo neck angle must be precisely cut so the neck tips back far enough or mounted high enough so the strings are close enough for comfortable fretting and far enough from the frets to prevent the strings from striking the frets… Usually called buzzing.
  • Before we get into the angle of the neck of the banjo, let’s leave this conversation about the curvature of the truss rod at this: if the curvature of the neck is correct so that it follows the vibrating shape of the strings, then there’s nothing more the truss rod can or should be expected to do.

The truss rod does not change the neck angle that it is mounted to the body, just the neck curvature.

The Coordinator Rod(s)

The rod or rods that run through the middle of the body of the banjo serve three functions: they hold the neck tightly to the banjo, they help “stabilize” the banjo’s rim and the rod that is closest to the player’s tummy can be used for very minor action adjustments. Some banjos have one rod (like Deering’s Goodtime banjos and several Vega models as well) and some have 2 rods like the Deering Sierra, Deluxe, etc.

  • The stabilizing function basically means that the rod helps keep the rim round by adding some rigidity to help resist the constant string tension that makes the rim want to compress or twist.
  • The lower coordinator Rod, (the one closest to your tummy) in addition to helping stabilize the rim from compression or twisting, is fastened on the neck end to one of the hanger bolts in the heel of the neck and holds the neck tightly to the body. The end of the lower rod that is held in place by two half inch nuts which can be used to slightly raise or slightly lower the string height above the fingerboard. So in essence, the lower rod can make minor neck angle adjustments to either raise or lower strings for playing comfort. However, the amount of adjustment is very small and can only be considered useful for “finessing” or “making very minor adjustments” to the angle of the neck.
  • The reasons for this are - The lower rod can exert so much pressure on the rim that the tone of the banjo will be stifled or pinched because the lower rod actually bends the rim in order to make the change in the string height.
  • A banjo rim that has excessive pressure squeezing it together pushing it apart does not vibrate as freely as one that has little to no pressure.
  • That is why the angle at which the neck is cut is critical for a high quality banjo.  A poorly cut neck angle cannot be corrected by super tightening a coordinator Rod. (Although some folks do it to compensate for incorrectly angled necks.)  However, very small adjustments can sometimes enhance the playing enjoyment and have virtually no negative effect on the tone of the banjo.

In banjos that have two coordinator rods, the rod that runs in the middle of the body of the banjo (the one that is closest to the strings) is strictly a stabilizing device and also fastens the neck to the body of the banjo. It is not capable of any action adjustment whatsoever.

A Coordinated Effort

When a banjo neck has the proper curvature for the tension of the strings being used and the neck angle is properly cut, the banjo will play its very best.

  • For example, Deering and Goodtime banjos are designed so that the first four strings are just about 1/8 of an inch above the 22nd fret. This is considered a “low” action by most banjo players. Some players like to have their strings just a little lower and they play so softly that they don’t create buzzing of the strings against the frets. Also, some players who play more aggressively, will prefer to have their strings higher than 1/8 of an inch.
  • There are some players who prefer to have their strings a full one quarter of an inch above the 22nd fret. Most players consider this a “high” action. For an action this high, a Deering banjo would have to have a specially cut neck angle because no amount of coordinator Rod adjustment would raise the strings this high without seriously distorting the round wood rim and affecting the tone severely.
  • Most of the time a coordinator Rod adjustment can raise or lower the strings approximately 1/32 of an inch without creating too much tone change. There are players who believe the rim should have absolutely no torquing tension from the coordinator rods. There are also players who believe the banjo sounds a little better when there is just a little tension on the coordinator rods whether it’s squeezing the rim together slightly or spreading the rim apart slightly.
  • Essentially though, the best playing banjos always start with a properly cut neck angle. This allows for very minor adjustments of the strings slightly up or slightly down to suit the players purpose.
  • On banjos with a truss rod, once the rod is adjusted to the correct curvature for the strings being used, then the majority of the action adjustment comes from the proper neck angle and very minor adjustments to the coordinator rods.
  • Some electric guitar players who enjoy playing with devices that create electronic distortion will sometimes insist on a neck that is virtually straight. This can work for them as it allows for a very light touch but any string buzzing is camouflaged by the electronic distortion they are utilizing in their amplification system. This is contrasted by an electric jazz guitar player, who is creating a very clear tone where a flat fingerboard is virtually impossible to use without hearing the buzzing sound of the strings rattling against the frets.

"Hot Rods" Banjo Set Up Conclusion:

As banjo players, we are all working toward a very clear tone. With the exception of course of some of the new, young players who are adapting their banjo playing to rock ‘n roll music and using electronic distortion with their banjos like they do with their guitars.

When searching for a repairman for your banjo, be certain that your repairman works on acoustic guitars and banjos so the understanding of the neck curvature is part of their everyday routine. Electric guitar techs may be extremely skilled but if someone recommends the fingerboard be completely flat, this will not work for your banjo adjustments.

So, the truss rod must have the correct amount of relief adjusted into the neck or, for banjos with no truss rod in the neck , the neck must be shaped or carved with the proper amount of curve built into the neck. This is where the action adjustment starts.

Next, a banjo should have the tension of the head adjusted to the tone that the player likes with the bridge height that is compatible with the neck angle.

And finally, the neck angle must be extremely precisely cut so that the angle is compatible with the height of the bridge in the curvature of the neck for the most comfortable playability and clearest tone.

Adjusting coordinator rods and truss rods in Deering banjos is simple. What can cause complications is expecting adjustments to have more effect than they are designed to have. Trying to correct a neck angle more than string movement of 1/32 of an inch at the 22nd fret is asking for tone trouble or even part breakage for both the truss rod and the coordinator rods. Fortunately, Deering banjos generally don’t need these kinds of massive adjustments.

… And that’s one major reason Deering banjos are fun to adjust in service.

Topics: banjo maintenance, Banjo Set Up, Your Deering

Barry Hunn

Written by Barry Hunn

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