Everything You Need To Know About Guitar Tuning Machines

Everything You Need To Know About Guitar Tuning Machines

If you hear new-age guitarists talk about tuners, they probably mean guitar-tuning devices and apps. However, this term used to have a different meaning. A properly tuned guitar will sound at its finest, and the prerequisite for that is having a set of properly functioning machine pegs.

There is more to guitar tuners, than just cranking the gears. What if a peg comes loose, or if it gets too worn over time, and your tuning is becoming more and more inconsistent?

Is it possible to effectively use guitar tuning machines even if you don’t know anything about them? Absolutely.

However, learning how guitar tuners work, how to install & replace them, and how to properly apply guitar tuning machine maintenance may prove to be invaluable knowledge in the long run; we’re here to break down everything there is to know about them, so let’s start from the top.

What Are Guitar Tuning Machines?

Tuning machines, machine heads, gears, pegs, or simply tuners are mechanical devices designed to help guitar players tune their guitars. This is done by tightening or loosening the pegs, which increase or decrease the string tension, respectively.

Both electric and acoustic guitars typically feature six of them - one for each string. If your guitar has more than 6 strings, it will need additional tuning pegs until the numbers match. As you can guess, each tuning machine governs the tension of a single string, and this is universal across all types of guitar tuning machines.

Tuners are typically located on the guitar’s head. The so-called “headless” guitars are equipped with a unique type of tuning machines that are located below the bridge but serve the same purpose as conventional pegs.

Different Types of Guitar Tuning Machines & How They Work

Several types of guitar tuning pegs exist, although, for simplicity’s sake, we could group them into “regular” and “locking” tuners. All other categorizations simply highlight the differences in terms of maintenance and aesthetics between different types while they’re functionally almost identical.

All tuners operate on a simple principle - turning them clockwise tightens the string while turning them counterclockwise loosens it. It’s important to note that this is only true as long as the strings are properly run through and around the tuners.

Whether you’re buying a new set of tuning pegs or simply want to learn more about how they work, I’ll explain the most popular machine head types below.

Open-back & sealed tuners

Depending on whether the tuning peg is exposed or covered, it can be described as open-back or sealed.

The first difference between the two is largely based on aesthetics - some guitarists like having the ability to watch the cranking gears as the strings are tightened/loosened, while others prefer closed-back tuners because they look more refined.

From a functional standpoint, caring for open-back tuners is easier, but they wear faster as they’re exposed to a variety of harmful factors (e.g. dirt and dust). Lubricating them is considerably simpler and can be done without removing the pegs from their posts. Sealed tuners, on the other hand, require significantly less care and tend to last longer.

Both types serve the same purpose. As you turn the peg, the worm gear moves and tightens/loosens the string. The only difference is that you won’t actually see the worm & pinion gears on a sealed tuner.

Side-mounted & inline tuners

Depending on whether there are two pairs of three tuning pegs mounted on each side of the guitar’s head or a single set of six placed horizontally along it, we have side-mounted and inline tuners.

Both types work exactly the same, but there is one small difference; inline tuners are better suited for guitars with taller headstocks, while 3x3 side-mounted tuners (or 3L+3R tuners) require a wider head. Theoretically, any set of tuning pegs could be placed on almost any guitar, but having a suitable headstock allows luthiers to find a proper angle without having to rely on string trees too much.

Regular & locking tuners

Design-wise, the invention of locking tuners changed the game for guitarists worldwide. These contraptions may look the same as regular tuning pegs on the outside, but they feature a simple locking pin that completely blocks all string movement.

On the other hand, strings run through “regular” tuning machines will always wiggle at least a bit. Whenever you play, the vibrations will make them move, but they’ll quickly resettle afterward. With lock-in tuners, this doesn’t happen at all and leads to more consistent intonation.

How to Install Tuning Pegs

The process of setting up new tuning machines is a breeze on acoustic guitars and slightly more complex on electric ones. The main difference here is that modern-day electric guitars usually come equipped with more advanced bridge & saddle designs, but the end line is the same - you’ll need to run your strings through each peg.

It’s important to note that tuners don’t come in universal sizes; they come in a variety of shaft sizes, diameters, and screw patterns. More importantly, some tuners are meant to be placed in a straight line (in-line tuners) while others are supposed to be mounted on the sides (3x3).

Take a look at the headstock of your guitar, measure the diameter of each hole, and use our guide to determine which type of tuners suits your needs the best. After that, simply follow these steps to install your tuning machines:

  1. Place the pegs in their respective slots
  2. Place tuner washers on the top side of each peg
  3. Place a sleeve on top of each peg and turn clockwise to tighten
  4. Adjust the angle of each peg so that they are all facing upward relative to the headstock

FAQs About Guitar Tuning Pegs

How to replace tuning pegs on acoustic guitar?

Most acoustic guitars use 3x3 side-mounted tuners. Use an appropriate screwdriver to remove the screws on the back of each peg, and remove the tuners by hand. Then place the new pegs in their respective slots, place washers and sleeves on each, and tighten each screw either by hand or with a screwdriver (depending on the model). 

How to change tuning pegs on electric guitar?

First, remove the sleeves and washers on each tuning peg, and pull out the tuners by hand. Then put new tuning machines into each socket, place washers on top of the screws, and finally put the sleeves back. Tighten the sleeves and run your strings through each peg. Find some guitar tuners recommendations here.

Are tuning pegs universal?

No, tuning machines come in a variety of shapes, sizes, and types. It is important to choose tuners that can snugly fit into the headstock holes of your guitar. You need to choose the proper tuning machines for your guitar.

What are the tuning knobs on a guitar called?

The tuning knobs, commonly known as tuners, are also called tuning pegs, guitar tuning machines, tuning keys, machine heads, pegs, and gear heads; these terms are synonyms, and all describe contraptions used to tune a guitar’s strings.


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