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Blog: Guide: How to Measure a Lock Cylinder Correctly and Determine the Right Length

The lock cylinder is a crucial part of the door that ensures your security. Before purchasing a new cylinder, it’s essential to measure the correct length to ensure it fits perfectly in your door. A poorly measured cylinder can compromise security or protrude unattractively from the door. In this step-by-step guide, we’ll show you how to measure a door cylinder properly. It’s crucial to measure the lock cylinder accurately.

Why is the Correct Length Important?

The length of a lock cylinder must be precisely matched to the thickness of the door and the existing fittings. A lock that extends too far from the door poses a security risk, as it can be easily pulled out or broken by burglars. If the cylinder is too short, locking the door may become difficult, or it might not fit at all.

1. What You Need

Before you begin measuring, ensure you have the right tools at hand. You will need:

  • A tape measure or caliper
  • A screwdriver (to remove the cylinder, if it’s already installed)
  • A new lock, if you plan to replace it

Don’t have a lock? Check out Winkhaus for options.

2. Remove the Lock Cylinder

If the cylinder is already installed in the door, you’ll need to remove it first to take accurate measurements:

  1. Loosen the screw: Remove the fixing screw that holds the cylinder in the door. This is located on the narrow side of the door at the height of the cylinder.
  2. Turn the key: Insert the key into the cylinder and turn it slightly to release the cylinder from the door. With the correct position, the cylinder can be easily pulled out.

3. Measure the Lock Cylinder Correctly

The total length of the cylinder consists of two sections: the length on the outside and the length on the inside of the door. These can vary, as the fittings on the outside and inside often differ. Be sure to exclude models where it’s difficult to measure the cylinder correctly.

  1. Measure from the center of the cylinder: Place the tape measure or caliper at the center of the cylinder. The center is marked by the screw hole (the fixing point).
  2. Determine the outside length: Measure the length from the center to the far end of the cylinder on the outside of the door.
  3. Determine the inside length: Measure the length from the center to the end of the cylinder on the inside of the door.

4. Key Measurements for Measuring a Lock Cylinder Correctly

  • Outside measurement (A): The length from the center of the cylinder to the outside of the door (including fittings). The cylinder should ideally be flush to minimize the risk of burglary.
  • Inside measurement (B): The length from the center to the inside of the door. This can be slightly longer, as it doesn’t pose a significant security risk.

Record both measurements (A and B). These dimensions are essential when ordering a new door cylinder. A typical measurement might be “30/35,” meaning the cylinder is 30 mm on the outside and 35 mm on the inside.

5. Measuring the Cylinder with the Lock Installed

If the cylinder is firmly installed and you don’t want to remove it, you can also measure the length directly on the door. Simply measure the protrusion of the cylinder on both the outside and inside and add this to the thickness of the door. However, this method is less accurate, as fittings or covers may distort the measurement.

Conclusion

Measuring the correct cylinder length is crucial for ensuring both the functionality and security of your door. Be careful when measuring and choose a cylinder that fits your door perfectly. If you’re unsure or encounter difficulties, don’t hesitate to contact our professional locksmith service. We’re happy to help and offer advice on how to measure your lock cylinder correctly!

16. October 2024