Lock Installation & Repair Flashcards

What is the commonly recommended minimum bolt throw for a residential deadbolt?

Answer: 1 inch

A 1-inch throw resists spreading and prying far better than shorter bolts.

Which upgrade most improves a door jamb's resistance to kick-ins?

Answer: Longer strike plate screws into the framing stud

3-inch screws anchor the strike into the wall stud rather than just the thin jamb.

What are the two standard backset dimensions for residential bored locks?

Answer: 2-3/8" and 2-3/4"

Backset is measured from door edge to bore center, and 2-3/8" and 2-3/4" are the standard sizes.

What are the standard hole sizes for a cylindrical lock installation?

Answer: 2-1/8" cross bore and 1" edge bore

Standard prep is a 2-1/8" face bore and a 1" edge bore for the latch.

A deadbolt binds only when the door is closed in humid weather; what is the most likely cause?

Answer: Door swelling or misalignment between bolt and strike

Swelling shifts the door so the bolt rubs the strike hole edge.

Where is a mortise lock body installed?

Answer: In a rectangular pocket cut into the door edge

Mortise locks sit in a routed pocket in the door's edge.

Which ANSI/BHMA grade rates the highest-security and durability for commercial locks?

Answer: Grade 1

Grade 1 is the top rating, with the strictest cycle and strength tests.

What is the best lubricant for a sticky pin tumbler lock?

Answer: Dry graphite or PTFE lubricant

Dry lubricants don't attract dust or gum up the pins like oils do.

A customer's key works poorly after being copied several times; what is the best fix?

Answer: Cut a new key by code or from the original key

Copies of copies compound cutting errors, so cutting from the original or code restores accuracy.

The deadbolt turns freely but the bolt does not move. What is the likely failure?

Answer: Broken tailpiece, cam, or connecting link

If the cylinder rotates without driving the bolt, the connection between plug and bolt is broken.

What tool holds the top pins and springs in place when removing a plug during rekeying?

Answer: Plug follower

The follower pushes the plug out while keeping driver pins and springs in the chamber.

Rekeying a pin tumbler cylinder to a new key mainly involves changing what?

Answer: The bottom (key) pins

Different bottom pin lengths match the new key's cuts while drivers stay.

A door's latch doesn't fully extend into the strike; which is the first thing to check?

Answer: Strike alignment with latch

Misalignment between latch and strike is the most common cause of incomplete engagement.

A broken key fragment is stuck in a cylinder. Which tool is the appropriate first choice?

Answer: Broken key extractor

Extractors grip the fragment's cuts without damaging the plug.