Repairing Twisted Necks
An Example of A Twisted Neck
Fingerboard is thinned when planeing to straighten
The neck pictured above twisted towards the treble side which is easy to spot when looking at the peghead. In this instance I was able to plane the fingerboard to render it perfectly level and return the instrument to playable condition. When the instruments neck has taken a set and stopped twisting this can be a permanent and very satisfactory repair.
Twisted Necks
De Plane, De Plane (or not)
My definition of 'twisted neck' is one that is warped in the same way that you would ring out a towel...as if one had gripped the peghead and turned it like a door knob. This is not the same as a bow. Not all necks that are twisted are good candidates for repair, in fact many must be replaced.
When faced with this kind of problem many things factor into the decision to repair or replace. First off, does the neck have other problems? Necks that flex and bow easily when stressed may not have the stability to behave. Once the board is thinned, it will have even less material to stiffen it. Secondly, is the fingerboard heavily inlayed? Heavy planeing will thin inlays and can even destroy some completely depending on their thickness which can be nearly impossible to know ahead of time. Removing each inlay (reproducing those that break) and deepening each inlay groove after planeing is an enormous job, one that I would rarely consider worth the effort.
Also, the amount of twist will obviously dictate the amount of planeing required and the board must be thick enough to accommodate this.
Age is another factor...when I see a one year old guitar with a neck already starting to twist I fear the player might be in for a bad ride. The last thing I'd want to do is have someone throw good money away if neck replacement is inevitable.
As I stated before, many things factor into the decision as to how to repair or if one makes the attempt. The above instrument is a classical guitar and neck removal is not possible eliminating the option of neck replacement. In my assessment of this particular instrument, the neck had taken it's "set" and was very stiff. I felt that planeing it was a viable option with better than average hopes of a lasting repair...I rarely consider any options that I feel are merely a temporary fix. If the neck had shown signs of weakness or other "squirrleyness" I may have opted for a thicker fingerboard (which would still have to be planed) in hopes of stiffening the neck.
What about un-twisting a neck? I had to throw that question in because I hear it so often. Many have envisioned some wonderful contraption that heats, clamps and contorts a twisted neck back to a normal position, but unfortunately that is a bit of a fantasy.
When wood, any wood, be it the 2' x 4' on your deck or the chunk known as a guitar neck decides to go it's own way you'll be hard pressed to convince it otherwise. That is why I make no attempt to force a change in it's shape with heat. As an illustration I point to that one plank in the deck with 6 screws holding the tip down, each year it pops up again and more screws are added. There's no more tension or stress on it than any other plank, it has the same screws mounting it to the structure as all the others but there it goes, curling towards the heavens.
Now you can understand the reasoning behind planeing the surface flat and physically changing it as opposed to heating it, bending it and hoping it wants to stay that way. If we are dealing with a piece of wood which has taken a set and ceased changing we have a very good chance of rendering a long term repair.
Squirrelly Necks
It's not twisted and the truss rod works but this thing ain't right! These are real joys to behold. On occasion you will find necks that have what many refer to as an 'S Curve' or as I like to call it "a mind of their own". To me, this is a neck that does not 'relieve' or bow normally. Bass necks can be particularly painful as the truss rod attempts to straighten the neck only to change it's shape...not exactly straighten it. The board takes on a bit of a roller coaster shape under tension that makes it difficult to adjust. If you pay close attention when adjusting the truss rod you will see some that really do some crazy stuff. Like what? Like, instead of straightening the neck, tightening the truss rod simply changes the point of greatest relief...instead of the dip being here it's there.
Even though you could hypothetically plane it's fingerboard perfectly flat or level the frets after the neck is clamped in a string tension simulating jig, these necks are normally just a pain to work with. And because they are most often seen on inexpensive instruments, time and effort must be kept to a minimum or the investment to repair may exceed the instruments value. When I know this is the case with a particular instrument I simply avoid them altogether.
Special Considerations and Tougher Problems
There are those necks which create obstacles to our common methods of repair, they can create quite a challenge.
