Shimming the neck on a guitar is a common adjustment technique used by guitarists and luthiers to improve playability, correct neck angle, and optimize string action. It involves placing a thin piece of material, called a shim, between the neck and the body or the neck pocket of the guitar. This simple yet effective method can make a significant difference in how a guitar feels and sounds, especially if the neck angle is too shallow or the action is uncomfortably high. Understanding how and when to shim a guitar neck is essential for maintaining optimal performance without causing damage.
What is a Guitar Neck Shim?
A guitar neck shim is a thin piece of material, usually made from wood, plastic, or even metal, that is inserted between the guitar neck and body. Its primary purpose is to adjust the angle at which the neck sits relative to the guitar body. By slightly tilting the neck forward, shimming can lower string action, making it easier to play while maintaining proper intonation. Shims come in various thicknesses, typically ranging from 0.1mm to 1mm, allowing for precise adjustments depending on the guitar’s needs.
Materials Used for Shimming
Different materials can be used to create a shim, each with its advantages. Common options include
- WoodThin strips of maple, mahogany, or basswood are popular because they are easy to shape and match the guitar’s natural material.
- PlasticDurable and easy to cut, plastic shims are often used in modern guitars and provide a consistent, stable adjustment.
- MetalLess common, but some luthiers use aluminum or brass for permanent, precise adjustments.
Choosing the right material depends on the desired tonal effect and the guitar’s construction. Wood is often preferred for acoustic guitars because it resonates naturally with the body, while plastic is favored for electric guitars due to its ease of use and durability.
Why Shim a Guitar Neck?
Shimming the neck is typically done to correct playability issues that cannot be fixed by adjusting the truss rod or bridge alone. Common reasons include
- High string action at the first few frets
- Neck angle too shallow, causing poor intonation
- Difficulty playing chords or fast passages due to uneven action
- Improving overall comfort and feel without permanent modifications
By adjusting the neck angle with a shim, players can achieve a lower, more comfortable string height and better overall balance between the neck and bridge. This is especially useful on bolt-on neck guitars like Fender Stratocasters or Telecasters, where the neck angle is adjustable through shimming.
When Not to Shim
While shimming can solve many problems, it is not always the right solution. Avoid shimming if
- The guitar has a set neck (glued-in) and the neck angle cannot be easily adjusted
- The issue is caused by a warped neck or broken truss rod
- The guitar already has proper action and intonation, and shimming might overcompensate
Improper shimming can negatively affect playability, neck stability, and even tone. In some cases, consulting a professional luthier is recommended to ensure the adjustment is safe and effective.
How to Shim a Guitar Neck
Shimming a guitar neck is a straightforward process, but it requires precision and care. Here’s a step-by-step overview
Step 1 Remove the Neck
For bolt-on neck guitars, remove the neck screws carefully and set the neck aside. Keep all screws and hardware organized to avoid losing any parts. It’s important to handle the neck gently to prevent scratches or damage.
Step 2 Choose the Shim
Select a shim of appropriate thickness. Start with a thinner shim, as it’s easier to add material than to remove it later. Some players cut shims from guitar picks, thin wood strips, or specialized pre-made shims designed for guitars.
Step 3 Position the Shim
Place the shim in the neck pocket, typically at the end closest to the bridge. The angle of insertion is critical the thicker end of the shim should be toward the body to tilt the neck forward slightly. Ensure it sits flush and does not shift during reassembly.
Step 4 Reattach the Neck
Carefully align the neck back into the pocket and reinsert the screws. Tighten them gradually and evenly to avoid uneven pressure. Check for movement and ensure the shim remains in place. A properly installed shim should feel stable and secure once the neck is bolted down.
Step 5 Check Action and Intonation
After reassembly, tune the guitar and check string action at the first fret and around the 12th fret. Adjust the bridge height or saddle if necessary to fine-tune the string height. Play chords and scales to ensure comfortable playability. The goal is smooth, even action with accurate intonation across the fretboard.
Tips for Successful Shimming
- Always start with a thin shim; multiple thin layers are easier to manage than one thick piece.
- Use smooth, hard materials to prevent movement or compression over time.
- Test the guitar thoroughly after installation to ensure playability improvements.
- Document the shim placement and thickness for future reference or adjustments.
- If unsure, consult a professional guitar technician, especially for high-value instruments.
Benefits of Shimming the Neck
Properly shimming a guitar neck offers several advantages
- Lower string action for easier fretting and reduced hand fatigue
- Improved intonation, particularly on bolt-on neck guitars
- Enhanced overall playability and comfort
- Minimal permanent modification, making it reversible if needed
- Ability to fine-tune neck angle without major luthiery work
Shimming the neck on a guitar is an effective method to correct neck angle issues and improve playability, especially on bolt-on neck guitars. By inserting a carefully chosen shim between the neck and the body, players can lower string action, improve intonation, and enhance overall comfort without permanent modifications. While the process requires precision and care, it is accessible to both DIY enthusiasts and professional technicians. Understanding the purpose, materials, and proper technique for shimming ensures that guitarists can maintain optimal performance and enjoy a more comfortable, responsive instrument. Whether adjusting a vintage Stratocaster or a modern bolt-on guitar, shimming is a valuable tool in the pursuit of perfect setup and playability.