Lock Installation & Repair Flashcards

Which of the following is the most appropriate tool for mortising a door for lock installation?

Answer: Mortising jig

A mortising jig is the most appropriate tool for mortising a door for lock installation because it provides a precise and consistent template. This specialized tool guides a router or chisel, ensuring that the mortise (the recess for the lock body) is cut to the exact dimensions and depth required for a secure and flush fit. While a wood chisel can be used, a jig significantly improves accuracy and efficiency, especially for professional installations.

What is the standard backset measurement for most residential locksets?

Answer: 2-3/4 inches

The standard backset measurement for most residential locksets in North America is 2-3/4 inches (70 mm). This measurement refers to the distance from the edge of the door to the center of the bore hole where the lock cylinder or spindle passes through. While 2-3/8 inches is also common, 2-3/4 inches is widely considered the most prevalent standard for exterior and interior residential doors.

When installing a deadbolt, what should be checked to ensure smooth operation?

Answer: Strike plate alignment

When installing a deadbolt, checking the strike plate alignment is critical to ensure smooth and proper operation. The strike plate is the metal plate installed on the door frame that the deadbolt extends into. If it's misaligned, the bolt may bind, not fully extend, or fail to engage securely, compromising the lock's function and security.

What is the function of a latch bolt?

Answer: To extend and hold the door shut

The primary function of a latch bolt is to extend from the edge of the door into the strike plate on the door frame, thereby holding the door shut. Unlike a deadbolt, a latch bolt is typically spring-loaded and has an angled face, allowing the door to be closed and latched without needing a key or turning a knob, though it can be retracted by turning a knob or lever.

Which component prevents a lock cylinder from being turned without a key?

Answer: Pin tumblers

Pin tumblers are the crucial components within a lock cylinder that prevent it from being turned without the correct key. These small pins, arranged in sets of driver pins and key pins, must be precisely aligned by the bitting of the correct key to create a shear line. When aligned, the cylinder can rotate, allowing the lock to open; otherwise, the pins block rotation.

Which tool is best for removing a broken key from a lock cylinder?

Answer: Key extractor

A key extractor is a specialized tool designed specifically for removing broken keys from a lock cylinder. It typically features thin, barbed, or hooked ends that can be inserted into the keyway alongside the broken key fragment. These hooks can then grip the key, allowing it to be carefully pulled out without damaging the lock mechanism.

What is the main reason to install a reinforcing strike plate?

Answer: Increase door security

The main reason to install a reinforcing strike plate is to significantly increase door security. Standard strike plates are often thin and secured with short screws, making them vulnerable to forced entry attempts like kicking or prying. A reinforcing strike plate is thicker, extends further into the door frame, and is secured with longer screws, providing much greater resistance against brute force attacks.

What is the purpose of a cylinder retaining clip?

Answer: Secure the cylinder in place

The purpose of a cylinder retaining clip, often called a C-clip or spring clip, is to secure the lock cylinder firmly within the lock body or door. This clip fits into a groove on the cylinder and against the lock mechanism, preventing the cylinder from being pulled out or pushed through the door. It ensures the cylinder remains stable and functional during operation.

Which lock type is most commonly used for securing exterior residential doors?

Answer: Deadbolt

A deadbolt is the lock type most commonly used for securing exterior residential doors due to its superior security features. Unlike a spring-loaded latch bolt, a deadbolt cannot be forced open by prying or shimming because its bolt is solid and has no spring mechanism. This provides a much higher level of resistance against forced entry, making it essential for primary door security.