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What are keypins?

Each key on the piano has two pins – the front rail pin and the balance rail pin. Both keypins keep the key in its  proper position as it rocks back and forth when a note is played.


Why do keypins go bad?

Over time, the keypins on your piano may corrode. In order for keypins to work properly, they have to be slippery enough to allow the key to move through its full range of motion. You may notice this when you experience unusual resistance when playing the piano. Ultimately, corroded keypins can cause excessive wear on the bushings, resulting in wobbly keys.

You can see corrosion on the pins in the form of bubbles, the way that you might see a bubble on the outside of a car when it’s rusting.

Polishing vs replacing keypins

There’s a difference between tarnishing and full-on corrosion. If the pins are tarnished, a simple polishing should be all it takes to bring the keys back to good working order. However, if the surface of the pins becomes pitted, this is a sign that corrosion has set in and they need to be replaced.

How are old keypins replaced?

To access the pins, we take off the keys and the keyframe so that the work can be done on a work bench. For grand pianos, we remove the action and upper stack.

Using a vice grips, we gently turn the keypins back and forth to remove them. It’s important to make sure that you aren’t too aggressive so that you don’t make the holes for the pins any larger than they are. This would only make a bad situation worse.

Next, we measure the pins with a micrometer to determine their exact size. After taking measurements, new pins are inserted into the holes. Typically, a press is used for this task to make sure that the nickel-plated exterior of the pins isn’t marred.

While we have the keyframe apart…

As with many services, having the keypins replaced is a good time to consider some other maintenance items. Having the piano worked on is costly, so it’s smart to get as much as possible taken care of now so that you aren’t coming back soon to have the whole instrument dismantled again.

Here are some repairs to consider while you’re having the pins replaced:

  • Replace bushings, since these may have been worn down by the bad pins
  • Replace old back rail cloth and front and balance rail punchings, which will cushion the keys and help them to operate silently
  • Elevate the keys to ensure that they’re at precisely the right height

Need piano service? Call Bruce Piano at 405-749-3540.

Whether your keypins need replacing or you have another problem with your piano, we can help. Call us or request piano service online and we’ll schedule a time to make these repairs.