Back bow and up bow on a guitar’s neck can be tricky enough to deal with, and they’re only bending on one plane. So, what happens when the neck of a guitar is both twisted and bowed? This is called a warped neck, and it’s one of the most difficult repair jobs of all on a guitar.
In this KillerGuitarRigs Guide, we’ll be teaching you all about warped necks, including how they happen, whether they can be fixed, and the steps to repairing a guitar with a warped neck. If you’re suffering from a warped neck yourself, or you’re just curious to learn more, you won’t want to miss this one!
- What is a Warped Guitar Neck?
- Can a Warped Guitar Neck be Fixed?
- What can Cause a Guitar Neck to Warp?
- What are the Symptoms of a Warped Neck?
- How to Fix a Warped Guitar Neck
- Inspect the Damage
- Non Invasive Neck Warp Repair
- Permanent Repair
- Steps to Fix a Warped Neck
- Final Thoughts on Repairing a Warped Guitar Neck
What is a Warped Guitar Neck?
A warped guitar neck is one that has twisted, making one side of the fretboard lower than the other. This can be a huge issue, and will cause a number of problems from inaccurate intonation, all the way through to severe tuning issues and a complete lack of playability.
Can a Warped Guitar Neck be Fixed?
Warped guitar necks can be fixed, although those with the most severe twisting may not be recoverable. This kind of job is typically best left to professional luthiers, but if the warp is only slight, you might be able to save quite a bit of money by attempting the repair yourself.
What can Cause a Guitar Neck to Warp?
There are 5 main factors that can cause a guitar neck to warp, and those are excess/uneven string tension, broken truss rod, incorrect humidity, exposure to extreme fluctuations in temperature, and sadly time.
Especially with older guitars, and those without adjustable truss rods, the tension of the strings is a major cause of neck warping. The average guitar has about 160lb of string tension on it at all times, which as you can imagine, causes a lot of strain, particularly on older necks. The natural way the grain of the wood is formed may cause it to twist under this tension over time, and this can be accelerated if the strings are over tightened, or too heavy a gauge is used.
Broken Truss Rod
The truss rod is responsible for countering the string tension, and with most modern guitars, is adjustable, allowing players to set how much neck relief they want to customize the playability of the guitar. If the truss rod is broken, this will allow the string tension to go unchecked, and can result in twisted and warped necks.
Because most guitars are made from wood, which is a natural product, they are susceptible to expansion and contraction caused by changes in humidity. In environments with excessive humidity, the wood fibers may absorb some of the moisture from the air, causing them to swell, and this can result in unnatural twisting and warping of the neck.
Similarly to humidity changes, wood will also expand and contract with changes in temperature. If your guitar goes from an extreme cold environment to a hot one, this can trigger thermal expansion, which again, can cause many issues with the guitar, with warped necks being amongst the worst results.
Sadly, as a combination of all the above, even if you look after your guitar perfectly throughout its entire life, the neck may end up warping. Of course, proper care and attention will mitigate the severity, but because the majority of guitars are made with natural products like wood, warping may be inevitable.
What are the Symptoms of a Warped Neck?
If your guitar has a warped neck, there’s a few things you might notice. The first symptoms are likely going to rear their heads as playability issues. You may find that notes choke out when bending where they didn’t before, and it’s almost a certainty that you’ll find issues with your intonation.
Besides that, if the warp is severe enough, you may even notice a difference in the feel of your neck. As Ben at Crimson guitars points out, this might not always be a bad thing, but the chances of your neck twisting in such a way that the intonation and tuning weren’t impacted, but the feel and playability were improved are pretty slim.
You might also find that the action of the guitar is affected. A warp would likely cause uneven action height, which would be extremely detrimental to your playability.
How to Fix a Warped Guitar Neck
Fixing a warped guitar neck is one of the trickier tasks in all of lutherie, and as such, if you’re not confident, or you’re dealing with a guitar that has either real monetary or sentimental value, you may want to consult with a professional before tackling this kind of project yourself.
These repair suggestions are primarily aimed at guitars with set necks. This kind of repair on a bolt on neck will almost certainly result in damage to the neck pocket, which will render the guitar practically useless.
Bear in mind, however, that neck warp repairs are never guaranteed to work, and you may find that the twist comes back. If you’re really sure you want to do this yourself, we’ve laid out the entire process step by step below.
Inspect the Damage
Before jumping into a repair, take some time to properly inspect the damage to see just how bad it is. There are a couple of ways to do this.
The Mk 1 Eyeball
The easiest, and most obvious way to check if a guitar neck is warped is to just look at it. Flip the guitar so you’re looking straight down the neck from the body end towards the headstock – if there’s anything more than a slight warp, you’ll be able to see it pretty clearly. To be doubly sure, flip the guitar around and look from the headstock towards the body.
If a visual inspection isn’t coming up with any obvious twisting, but you still feel something isn’t right, you’ll probably need to break out the feeler gauges.
Put a capo on the first fret, and using your finger, fret the string at the 17th. Then, using a 0.010” gauge, slide it between the fret and strings at the top, middle, and bottom of the fretboard at both the treble and bass sides.
Without going into granular detail about the distances you should encounter, you’re really checking to see that there isn’t a huge difference between the string clearance from the 1st string to the 6th. If the feeler gauge is tight on one side, and really loose on the other, you’ve got yourself a warped neck.
Non Invasive Neck Warp Repair
If you do have a warp, but you find that it’s very slight, you might want to think about a more non-invasive approach to repair. One of the cheapest, easiest, and least invasive approaches to neck warp repair is to use a custom string gauge.
This might involve buying individual strings, or combining different sets, but the aim is to increase tension on the low side of the warp, and decrease it on the high side. If the warp is twisting down towards the treble side, consider a heavier gauge for your 1, 2, and 3 strings, and use lighter strings for the 4, 5, and 6. This may help to balance the tension, and resolve the warp.
If you’ve tried balancing your string tension and it didn’t work, or the initial warp was too severe to even bother trying, you may need to take more drastic action with a heat and clamp repair.
Tools You’ll Need
Before getting started on fixing your warped neck, you’ll need to make sure you’ve got all the right tools for the job.
- Clothes iron
- Rubber pads
- A neck cradle
- A tension block
- Eye hooks
- Extra low E string
- Fine chisel
- Paint scraper
- Dead blow mallet
Steps to Fix a Warped Neck
Step 1 – Remove the fretboard
Set your iron as hot as it will go, and turn it to the maximum steam setting. When it’s heated up, you will want to move up and down the fretboard to start loosening the adhesive.
Don’t leave the iron still in one spot for too long otherwise you may end up burning the wood. After about 5 minutes of heating, you should start to see the fretboard come away from the neck. At this point you can take your fine chisel or paint scraper and gently insert it between the fretboard and neck, and carefully start prying the two apart.
If you encounter resistance while prying the fretboard off, you may need to use a dead blow hammer to push it through. Be sure to lift the fretboard away in equal measure from the top, middle and bottom to prevent snapping it. Take your time, and do not rush this stage.
When the fretboard is all the way off, you can proceed to step 2. Note, it’s not uncommon to start encountering fret sprout while removing a fretboard. If you have a bound fretboard, this may cause some finish damage, and regardless, will also likely result in you needing a fret dress once the neck is straight again.
Step 2 – Secure the Guitar
Before going any further, you’ll need to secure your guitar’s body thoroughly to your work bench. There will be torsional forces applied to the neck, and if the body isn’t secure, you may end up making the warp worse, or wasting your time and doing nothing at all.
Lay the guitar down, with the neck supported by the cradle right around the middle. Place your rubber pads in between the body and the clamps to prevent finish damage. Then, tighten the clamps until the guitar is properly secured, and cannot move in any direction.
Step 3 – Prepare the Tension Block
Take your tension block, which should be a solid piece of hard wood like oak or mahogany, and at a headstock’s width distance, screw in your two eye hooks. The tension block should then either be screwed or bolted into your work bench with the eye hooks lined up with the 3 and 5 position tuning pegs on a 3 x 3 headstock, or right around the middle of the headstock on a 6 in line.
Step 4 – Attach the Strings
Take one of the low e strings, and secure it to the 2nd string tuning peg, and then take the other string, and attach it to the 5th string peg. You’ll need to then secure each string to the respective eye hook.
Before putting the strings under tension, slot additional rubber pads in between the strings and the headstock to prevent any damage.
Step 5 – Tighten the strings
Turn each tuning peg until both strings are taught. At this point you’ll want to take your iron, again with the high steam setting, and heat up the neck. As the neck heats up, you’ll need to tighten the string on the high side of the warp.
Use quarter turns, and go very slowly to allow the wood to acclimatize, and also to prevent any catastrophic damage. After each turn, visually inspect the neck to see if it’s any closer to being straight again.
When the neck has been pulled straight, heat it up to set the lay. Keep it under the same tension for a minimum of 24 hours, but be sure to check on it regularly throughout this period. If the strings stretch from the tension, you may need to add an extra partial turn to maintain the shape.
Step 6 – Release the Tension
Once you’re satisfied with the way the neck is looking, very slowly release the string tension. If you release too fast, the neck might spring back to a warped condition. If all has worked as planned, the neck should be straight now.
Step 7 – Reattach the Fretboard
The last step is to reattach the fretboard. You’ll need to properly glue it down, and hold it with clamps for 24-48 hours to cure (or whatever the glue manufacturer’s instructions say). When the fretboard is reattached, restring, and your guitar (in theory) should once again be playable.
Before calling it a day, use your feeler gauges and once again check the distance between the frets and strings at the top, middle, and bottom to assess whether your repairs did the trick.
Final Thoughts on Repairing a Warped Guitar Neck
As mentioned, repairing a warped guitar neck (if it involves more than a change of string gauge), is a pretty serious task. If you’re just learning about lutherie, we highly suggest either taking on some additional projects first, or perhaps seeing if you can get a scrap or donor guitar to practice on before tackling your own.
As always, if you’re not sure, please take your guitar to a professional. The thought of a repair bill might be terrifying, but it’s never going to be as bad as having to scrap the whole guitar.