A homeowner's deadbolt has become noticeably stiff to operate. Which action should they try first?
ACall a locksmith — stiff deadbolts indicate internal mechanism failure requiring professional tools
BReplace the entire lock assembly with a new deadbolt
CApply an oil-based lubricant generously into the keyhole
DApply graphite powder into the keyhole
Graphite powder is the correct first step for a stiff lock. Oil-based lubricants attract and trap dirt and grit, making the problem worse over time. Replacement and calling a locksmith are both premature — stiffness is most commonly resolved by lubrication alone and takes under a minute. This is a case where understanding the mechanism prevents unnecessary expense.
Question 2 Multiple Choice
A homeowner buys a replacement deadbolt but isn't sure it will fit their door. Why do most replacement locks fit most residential exterior doors?
ABuilding codes legally require all residential doors to use identical hole patterns
BLicensed contractors always use the same manufacturer when installing original hardware
CNearly all exterior doors have a backset of 2-3/8 or 2-3/4 inches, and most replacement locks are adjustable to fit both
DDeadbolts are manufactured to fit only one universal hole size, regardless of brand
Residential door hardware is highly standardized around two common backset measurements. Most replacement locks ship with an adjustable latch that handles both, which is why a homeowner can walk into a hardware store, buy almost any deadbolt, and have it fit without measuring. This standardization is what makes DIY lock replacement practical for most people.
Question 3 True / False
A door lock that was recently lubricated still sticks. The most likely remaining cause is misalignment between the bolt and the strike plate.
TTrue
FFalse
Answer: True
After lubrication fails to resolve stiffness, the next most common culprit is a misaligned strike plate — the bolt no longer lines up cleanly with the opening in the door frame, often because the door or frame has settled over time. This is confirmed by watching where the bolt contacts the strike plate when the door is closed. Fixes range from tightening loose strike plate screws to chiseling the mortise slightly to match the bolt's actual path.
Question 4 True / False
Deadbolts can be forced open by sliding a flexible card along the door edge to push back the bolt — the same technique that works on spring latches.
TTrue
FFalse
Answer: False
This is a common misconception. Spring latches have an angled bolt that retracts when pressure is applied from the side — which is why the card trick works on them. Deadbolts have a square-ended bolt that does not retract unless explicitly operated by a key or thumbturn. This is precisely what makes deadbolts the security-critical component: they cannot be bypassed by lateral pressure.
Question 5 Short Answer
Why is graphite powder recommended for lock lubrication instead of oil-based products like WD-40?
Think about your answer, then reveal below.
Model answer: Graphite is a dry lubricant that reduces friction without leaving a sticky residue. Oil-based lubricants leave a film that attracts dust, dirt, and metal particles from the lock mechanism, which accumulate over time and eventually make the stiffness worse than before. Graphite provides lasting lubrication precisely because it doesn't trap contaminants.
Understanding the reason — not just the rule — lets homeowners apply it to other situations. The same principle applies to bicycle chains exposed to grit: wet lubricants work initially but attract debris; dry lubricants are better in dirty environments. In a lock cylinder, where tolerances are tight and contamination compounds quickly, the difference between graphite and oil is often the difference between a durable repair and a recurring problem.