Free Locksmith Lesson #3 - Shimming Open the Cylinder

Sometimes, when you have to re-key a lock cylinder that does not have an operating key, you must either pick it open - sometimes very difficult - or you can shim it open. In this lesson, I will teach you how to shim open a cylinder.

What you will need:

1. A standard Kwikset knob with the cylinder taken out.
2. A package of steel lock shims.
3. A Kwikset key blank.
4. A lock pick with the tip ground off.
5. A follower.
6. Lesson #1 and #2.

Our goal here is to get the plug in the shell too turn a quarter turn. We cannot do it without a key. So, we will stick a thin piece of shim in the rear of the cylinder and, using a pick in the front of the cylinder, lift the last tumbler up until it reaches the shear line. During this time, we will be pushing in on the shim, but lightly, so that, when the shear line is reached, the shim will slip forward and separate the bottom pin from the top pin. We will proceed then to the next pin, and the next, until the shim has separated every top and bottom pin in the lock cylinder. Then, after that is done, we can use any flat-bladed object to turn the plug.

Insert the shim between the bottom and top pins at rear of cylinder

If you do not want to use a pick, you can use a key blank. When you insert a blank, all of the pins are raised up into the top portion of the shell. 

Insert your shim in the rear of the lock and maintain a little pressure. Then, slip your key out slowly until your shim shoots forward. Sometimes, you will have to do a little back and forth with the key and the shim.

Using a pick to lift the tumblers

Once the plug turns in the shell, make sure it is turned a quarter turn. Then, insert your follower, and push the plug out of the shell.

Now, let's look at some facts about shimming. 

1. If you are working on a commercial lever and need to get the cylinder out, you must either have a key, pick it open, or use a lever removal tool (do a search for A-1 locksmith tools). Once the cylinder is removed, you can shim it.
2. Do not try to shim open high-security lock cylinders.
3. The Kwikset cylinder can be taken apart by removing the top cap. You won't be so lucky and the vast majority of lock cylinders. Schlage's residential cylinders have a floating cap. If you remove it, which I think you should try, you could damage it.
4. Most commercial lock cylinders, if they cannot be shimmed open, must be replaced. Also, it is worth noting that some higher-quality lock cylinders like Corbin-Russwin have spool-shaped top pins which will make it hard to shim. What happens is that your shim will advance and jam because it didn't find the shear line, instead it got caught on a spool. If you suspect you are shimming a cylinder with spool top pins, just be sure you raise the bottom pins up all the way so that you shim gets into the sheer line at the top of the bottom pin before your shim hits the spool top pin.
5. Be sure to practice this and get a feel for it. It won't take you long to learn this trick. Be sure to try doing it with the pick and the key blank.