Uneven keys are an unsightly side effect of a well-loved piano. If you play your piano a lot (or not!) you may notice that the felt holding up your piano keys has compressed. Over time, the material loses its integrity and the keys settle out of alignment.
It's an aesthetic issue, true, but when the keys are left out of whack, play can be affected. It can feel spongy, wobbly, or just "off," making it less pleasant or even trickier to play. Sound is altered, too, because the distance each key needs to travel to strike the hammer will not be consistent. That means uneven play volume.
The cure? Add paper punchings underneath the felt to prop up the key and bring the instrument back up to its former glory.
The difficulty of this job averages out to "intermediate." Technically, it's as simple as lifting a key off its pin, inserting a paper shim, and putting the key back... but even with a key leveling tool, this job requires so much trial and error, precision, and time, completing the job can be quite challenging. Set aside plenty of time if you attempt DIY key leveling.
See those wonky keys? You could fix that yourself!
- Paper punchings
- Key leveling tool AND/OR 4-foot level or long metal straightedge
- Bright flashlight
- Optional: Punching lifter tool
Before You Begin
Before we dive into the repair process, you'll need to assess whether you'll be leveling to the front rail or the balance rail.
By definition, your piano key is a simple machine: a lever that is balanced on a fulcrum. This fulcrum, or tipping point, is the balance rail. It's right in the middle of the key and controls the balance of the key while at rest.
When you're playing your piano, the keys need to stop at the correct place. Near the front of the key, hidden behind the keyslip, there is a pad called the front rail. This is the stopper for the key when it is depressed.
You can tell whether you need to level the balance rail or the front rail at a glance:
- If your piano keys look uneven when not in use, you will need to adjust the balance rail. This applies to a piano that's "smiling" at you, a piano with "crooked teeth," or one that looks uneven at rest. You do not need to touch your piano to determine if it needs the balance rail adjusted.
- If your piano keys aren't stopping at the right place when you press them down during play, the front rail needs to be adjusted. Don't worry about the actual distance that the keys travel, but the evenness of the stopping. If you're not sure, press an entire octave of keys at once. If some keys stop further down than others, you'll need to level the front rail.
Also, this guide is only intended for leveling the white keys. Leveling the sharps (black keys) requires a different technique, so for now, we're just talking about natural notes.
How to Level Piano Keys
First, check to see if there are foreign objects inside the piano. Even if you don't think this is the case, take a look anyway. You'd be surprised how much stuff falls in there! Our resident piano tech was once called to fix keys that were out of alignment only to discover a Spiderman figurine gumming up the works. More likely, your UFO will be something small like a paperclip or piece of paper.
If you can easily remove foreign objects trapped inside the piano, do that. You may need tweezers and a flashlight to do this correctly. If things are tangled up inside (like, say, an action figure) we suggest calling your local technician. While you're at it, giving your soundboard and pinblock a nice thorough cleaning wouldn't be a bad idea. It's not necessary for the leveling process, but it's something that needs to be done once in awhile. Clearing away dust and crud will make this process more pleasant anyway.
Now, open up your piano cabinet and remove the fallboard. That's the hinged cover that comes down over your keys. You may need a screwdriver for this. Many pianos have another bar, called the key rail stop, that will need to be removed. You may have even more cabinet parts covering or concealing the keys, so take the time to get acquainted with your piano while you open it up. If you have a grand, you'll need to pull out the action to access the keys. Remember, not all pianos are constructed the same, so be aware that your piano may look different than others shown in tutorials. Next, take off the keyslip (the wood in front of the keys) so you can access the keys more easily.
With the piano cleaned, opened, and keys accessible, you're ready to start leveling. We're outlining two methods: using a leveling tool, and the manual method.
Using a Key Leveling Tool
This is the preferred method not only because it's more precise, but because it's easier and faster. The key leveling tool is simple to use and eliminates eyeballing.
The bottom of the tool is flat, and it's meant to slide along the edge of the keybed. The pin (gold-colored in this example) gently rests on the keytop. It will drop below the flat surface on the top if the key is too low and rise up out of the hole if the key is too high. The tool's pin indicates a perfectly-leveled key by being flush across the top.
First, identify the key you'd like to use as your baseline. Generally, you would choose the keys at the extreme bass and treble ends of the piano. This is because these notes get the least amount of play and the existing punchings are not very compressed. Of course, every piano is different, so use your best judgment when setting your device.
When you've chosen your baseline key, align the tool. Do this by resting the flat metal bottom of the tool on the keybed. Tighten or loosen the screw on top to raise or lower the tool top. The gold-colored pin is floating loosely in the hole, so adjusting the height of the tool moves the pin up or down. Align the top of the pin to be flush with the flat surface to calibrate the device.
Now that your tool is set, slide over to the key you'd like to measure. Remember to keep the bottom of the tool flush with the keybed. If the pin drops down in the hole, you will need to add punchings. If the pin pops up, remove punchings (this is less common). This is how you will identify which keys need leveling and which don't.
To measure for the front rail, follow these same steps, but with the keys depressed as far as they will go.
This method works in a pinch and is best for balance rail adjustments. It's maybe less precise, but can be very effective if you're careful.
A 4-foot level should reach both the highest notes and the lowest. These notes aren't played very often, so their felt is in the best shape and you'll be raising up the other keys to match these extremes. Alternatively, you can use a long metal straightedge to determine which keys need to be raised. Again, we recommend using the extreme bass and treble keys as the standard. Note: If you do this, the straightedge tool must rest on both a bass key and a treble key to establish your "calibration level."
If your balance rail is way out of alignment, it will be obvious which keys need work. The image above shows three keys which definitely need to be lifted. But what about the others?
To check for less obvious issues, shine your bright flashlight from behind the level, towards you. If the light shines through a gap between the key and the level, it needs to be raised. You can double check this by very gently playing the key in question. If you hear the key tap against the level when it returns to neutral, it's in good shape and doesn't need to be leveled. If you don't hear the sound of the key striking the level, it needs lifting.
Replacing the Punchings
Now that you know which key needs work, remove the key. It's just resting on its pin and you've already removed the fallboard and bars holding it in place, so lift it straight up and out of the piano.
You will see two pins surrounded by felt and/or paper punchings. Remember, the balance rail pin is in the middle and the front rail pin is, well, in the front. The balance rail adjusts the key height when at rest and the front rail adjusts the stopping point while the key is depressed.
There might be punchings already placed on the pins. They can stay there, unless you're lowering the key. You can use tweezers to remove a punching, but we recommend a punching lifter tool. It's better suited for this delicate job.
To raise your key up and off the balance rain pin, you can simply place the punching(s) on the pin. They are already perfectly cut to fit precisely in its place. If there is a felt punching on top, lift it up, then add the paper punchings. Replace the felt.
You're working with very, very thin punchings -- just 0.001 inch thick -- so it may take several of them to raise the key to the correct height. Unless you have an expert eye, you'll have to try a few different punchings at different thicknesses to find the sweet spot.
When you've added the punchings, replace the felt top felt punching. Replace the key and test it out. If you were working with the balance rail, you can use your key leveling tool or straightedge to confirm the height. The front rail punchings are typically topped with a green heavy cloth punching. Remove the green one, place the new/additional paper punchings to the front rail pin, replace the green cloth punching, then replace the key.
If you were correcting the front rail, press the key all the way down and measure it.
If the key is leveled correctly, pat yourself on the back for a job well done and move on to the next key!
Adding paper punchings is really just a bandaid treament. This correction will last for years, yes, but if you're looking for a lifetime fix, you'll need to do precision gauge stacking, conceal thinner punchings between larger ones, use more permanent materials, and many other picky techniques which we're not going to cover here.
Also, note that this guide is for maintenance of home pianos. Should you be as precise as possible? Yes. Should you break your brain trying to make everything perfect? Not really, unless you're doing this professionally. If your keys are even, you're happy with the way it plays, and it looks correct, then you're in good shape.
Which punchings do you need?
It depends on your piano, but here's a quick cheat sheet to help you determine standard punching thicknesses. The very thin ones are conveniently color-coded.
White - 0.003
Green - 0.005
Pink - 0.007
Blue - 0.010
Manilla - 0.012
Grey - 0.015
Grey - 0.020
Grey - 0.025
Grey - 0.030
Grey - 0.040*
Grey - 0.045
Grey - 0.050*
Grey - 0.060*
Grey - 0.080*
(Punchings marked with an asterisk are only available for the balance rail, not the front rail.)