CRL Lock Installation & Repair — Questions and Answers
Question 1: What is the commonly recommended minimum bolt throw for a residential deadbolt?
- 1/2 inch
- 3/4 inch
- 1 inch (Correct answer)
- 1-1/2 inches
Correct answer: 1 inch
A 1-inch throw resists spreading and prying far better than shorter bolts.
Question 2: Which upgrade most improves a door jamb's resistance to kick-ins?
- Longer strike plate screws into the framing stud (Correct answer)
- A thicker coat of paint
- A shorter bolt
- A decorative strike plate
Correct 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.
Question 3: What are the two standard backset dimensions for residential bored locks?
- 1-1/2" and 2"
- 2-3/8" and 2-3/4" (Correct answer)
- 3" and 3-1/2"
- 4" and 5"
Correct 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.
Question 4: What are the standard hole sizes for a cylindrical lock installation?
- 1-1/2" cross bore and 1/2" edge bore
- 2-1/8" cross bore and 1" edge bore (Correct answer)
- 3" cross bore and 1-1/2" edge bore
- 1" cross bore and 2-1/8" edge bore
Correct 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.
Question 5: A deadbolt binds only when the door is closed in humid weather; what is the most likely cause?
- Worn key
- Door swelling or misalignment between bolt and strike (Correct answer)
- Broken spring in the cylinder
- Wrong keyway
Correct answer: Door swelling or misalignment between bolt and strike
Swelling shifts the door so the bolt rubs the strike hole edge.
Question 6: Where is a mortise lock body installed?
- Drilled into the door face only
- Surface mounted on the door
- In a rectangular pocket cut into the door edge (Correct answer)
- Inside the door frame only
Correct answer: In a rectangular pocket cut into the door edge
Mortise locks sit in a routed pocket in the door's edge.
Question 7: Which ANSI/BHMA grade rates the highest-security and durability for commercial locks?
- Grade 1 (Correct answer)
- Grade 2
- Grade 3
- Grade 4
Correct answer: Grade 1
Grade 1 is the top rating, with the strictest cycle and strength tests.
Question 8: What is the best lubricant for a sticky pin tumbler lock?
- Motor oil
- Dry graphite or PTFE lubricant (Correct answer)
- WD-40 only
- Cooking oil
Correct answer: Dry graphite or PTFE lubricant
Dry lubricants don't attract dust or gum up the pins like oils do.
Question 9: A customer's key works poorly after being copied several times; what is the best fix?
- File the new key
- Cut a new key by code or from the original key (Correct answer)
- Spray more lubricant
- Replace the strike
Correct 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.
Question 10: The deadbolt turns freely but the bolt does not move. What is the likely failure?
- Wrong keyway
- Broken tailpiece, cam, or connecting link (Correct answer)
- Bent strike plate
- Too much lubricant
Correct answer: Broken tailpiece, cam, or connecting link
If the cylinder rotates without driving the bolt, the connection between plug and bolt is broken.
Question 11: What tool holds the top pins and springs in place when removing a plug during rekeying?
- Plug follower (Correct answer)
- Pin tweezers
- Tension wrench
- Plug spinner
Correct answer: Plug follower
The follower pushes the plug out while keeping driver pins and springs in the chamber.
Question 12: Rekeying a pin tumbler cylinder to a new key mainly involves changing what?
- The driver pins
- The springs
- The bottom (key) pins (Correct answer)
- The cylinder housing
Correct answer: The bottom (key) pins
Different bottom pin lengths match the new key's cuts while drivers stay.
Question 13: A door's latch doesn't fully extend into the strike; which is the first thing to check?
- Strike alignment with latch (Correct answer)
- Key cut depth
- Cylinder keyway
- Doorknob finish
Correct answer: Strike alignment with latch
Misalignment between latch and strike is the most common cause of incomplete engagement.
Question 14: A broken key fragment is stuck in a cylinder. Which tool is the appropriate first choice?
- Hammer
- Broken key extractor (Correct answer)
- Drill
- Screwdriver
Correct answer: Broken key extractor
Extractors grip the fragment's cuts without damaging the plug.