An anti-snap locks is designed to resist a snapping attack on the cylinder. Old Euro profile locks have a weak cylinder that easily breaks when hit. It’s an easy and quick break-in technique beloved by burglars everywhere.
Replacing your current lock with an anti-snap lock takes less than 10 minutes. You don’t need any special tools other than a Philips screwdriver. No drilling needed.
In this post, we explain how to fit an anti-snap lock on your door.
1. Understanding cylinder measurements
Getting the measurements right is the most important bit. If you buy the wrong size, it won’t fit properly in your door.
Lock cylinders come in different sizes. Sizes are represented by a pair of measurements such as 35/35 or 40/50.
These indicate the external and internal measurements in mm.
It’s essential that you take the ext/int measurements of your existing lock and buy a cylinder that matches or is slightly shorter (if your current cylinder protrudes).
To do this, you need to remove the current cylinder.
2. Remove the existing cylinder
You most likely don’t need to remove your handle; only the cylinder.
Open the door and look for the cylinder-retaining screw on the side. Insert a key into the lock then use a screwdriver to loosen the cylinder screw until it comes out.
Push the cylinder gently from the outside as you twist the key until you feel the cylinder give way and slide out.
3. Take external and internal measurements
Take a ruler or tape measure and measure each half of the cylinder from the end to the center of the cam.
They may be equal in length or one side may be longer than the other.
Whatever the case, the most important thing is to note which measurement is for the external half (the part that faces outside) and which one is for the inside.
4. Buy the right anti-snap lock
Look for an anti-snap lock that matches the measurements you got. However, if your currently cylinder protrudes beyond the lock, look for a new one where the external measurement is a digit shorter.
5. Install the new cylinder
If you had put the old cylinder back, remove it again and put it aside.
Insert the new key into the new cylinder and turn such that the cam aligns with the cylinder. Push the cylinder into the door lock until it slides into place.
You may need to twist the key a bit to get the cylinder to slot into place perfectly. Check the outside part of the lock to make sure the cylinder is flush with the handle back plate. If it’s not, you may have to buy a smaller cylinder.
Note: When inserting the new cylinder, check the indications for the internal and external side. Only the external side has anti-snap protections. So if you insert the lock wrongly, your door will not be secure.
Finish by re-tightening the cylinder screw into the door.
Turn the key several times and check that the cam operates properly without any problem.
How an anti-snap lock prevents burglary
Different brands may have different anti-snap techniques. But the most common ones include:
- A stronger cylinder: The locks feature a stronger cylinder that can withstand more force. Even if it succumbs to a hit or twist, it only flexes rather than breaking off.
- Sacrificial cuts: Instead of the entire cylinder snapping, manufacturers will add one or two sacrificial cuts that break off during a snapping attempt. This shortens the cylinder, making it harder for the burglar to grip and break it. Even if part of the cylinder breaks, the lock remains secure.
- Flush cylinder: The easiest locks for burglars to snap are those with a protruding cylinder. They can simply hit it with a hammer or twist it with a pair of pliers. Most anti-snap locks feature cylinders that are flush with the handle back plate. They are harder to snap.
In addition to protecting your lock from a snap attack, most anti-snap cylinders are also designed to resist drilling, bumping and picking.