How to Shim a Lock

Lock shimming is a technique that professional locksmiths use when they need to open a lock cylinder without a key. It is important to mention that this is not an opening technique, meaning that if a client gets locked out of their house and we needed to gain entry, this isn’t a technique for that. Lock shimming is a technique for once you’ve already gained entry and you’re taking the locks off the doors to rekey or make a key for them.

There are only two items required to shim a lock. On the one hand, you need a blank key that fits into the lock cylinder and, on the other hand, you’ll need a lock shim. Lock shims are sold in packs of 25 and they are quite inexpensive. A single package allows you to shim around 300 locks.

Lock shimming is a really good technique to learn and there are three main reasons to support this: it’s inexpensive, it’s not going to damage the lock at all and, finally, it’s super easy once you learn how to do it. Let’s explain how to do it.

To begin with, grab a deadbolt and remove the tailpiece in the back. It’s always advisable to use some lubricant in the key lock if you stick the key and it’s kind of tight. Use the very tip of the blank key to move the bottom pin up and down in order to get the top pin and the bottom pin to meet at the sheer line.

So, once the key is in, grab the shim and make sure that the curvature is down. Put it in the back of the sheer line, which is where the top pin, springs and bottom pins of the plug meet. Make sure you keep the shim aligned with the lock cylinder bible (where the springs of the top pin are). Hold the shim, take the key and move it back and forth and shim the lock like that. Other way to do it is to hold the key and the shim to keep it straight while you’re shimming. Move the key slowly in and out while gently applying pressure on the shim. Keep in mind that if you apply too much pressure on the shim it’s not going to work. Go on until you shim the pins. Turn the key and remove the shim. At this point, you’re able to take it apart and rekey it.

Get your lock shims