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Question 1General Locksmithing Knowledge

Which type of key is cut on both edges and can be inserted into the lock in either orientation?

  1. A tubular key
  2. A flat steel bit key
  3. A double-sided edge-bitted key Correct answer.
  4. A single-sided cylinder key

Explanation

A double-sided edge-bitted key has bitting cut on both edges, so it can be inserted with either edge facing the pins. Single-sided keys and bit keys have one working orientation. Tubular keys cut on the end face, not the edges.

Question 2General Locksmithing Knowledge

In a pin tumbler cylinder, what is the function of the driver pins?

  1. They retain the plug inside the shell
  2. They seat in the key bitting to set the shear line
  3. They block the shear line unless lifted to the correct height Correct answer.
  4. They return the plug to the locked position after use

Explanation

Driver pins sit above the key pins and straddle the shear line when the correct key is absent, preventing rotation. When the key lifts each key pin to the right height, the drivers clear the shear line. Key pins, not drivers, contact the key bitting.

Question 3General Locksmithing Knowledge

A customer hands you a key stamped 'KW1'. Which keyway family does this blank belong to?

  1. Schlage C keyway
  2. Yale 8-pin
  3. Kwikset Correct answer.
  4. Weiser

Explanation

The KW1 designation is the standard Ilco/Silca blank identifier for the common Kwikset 5-pin residential keyway. Schlage C uses SC1, and Weiser uses WR-series designations. Yale keys use Y-series designations.

Question 4General Locksmithing Knowledge

Which tool is used to measure the depth of a cut on a key blade when duplicating by hand?

  1. A plug follower
  2. A pinning shoe
  3. A key caliper or depth gauge Correct answer.
  4. A tension wrench

Explanation

A key caliper or depth gauge measures cut depth from the blade bottom to the cut floor. Tension wrenches, plug followers, and pinning shoes are lock-service tools and do not measure key cuts. Accurate depth measurement is essential for manual code cutting.

Question 5General Locksmithing Knowledge

What is the primary purpose of a mortise lock's deadbolt?

  1. To hold the strike plate in alignment
  2. To control the handing of the lock body
  3. To provide a positive locking bolt that resists forced entry Correct answer.
  4. To latch the door shut while allowing it to swing open

Explanation

A deadbolt is a positive locking bolt that extends into the strike and has no spring-loaded bevel, so it resists being slipped or forced. The latch bolt, not the deadbolt, holds the door closed while allowing it to open. Strike plates and handing are separate concerns.

Question 6General Locksmithing Knowledge

Which keyway feature allows a master-keyed system to accept both a change key and a master key?

  1. A spring-loaded keyway shutter
  2. A wider keyway that accepts two blank profiles
  3. A removable core
  4. Two shear lines created by split or stepped pins Correct answer.

Explanation

Master keying works by creating more than one shear line in the cylinder, typically using split pins or master wafers. The change key aligns one set of breaks and the master key another. A wider keyway or removable core does not by itself produce master keying.

Question 7General Locksmithing Knowledge

A pin tumbler cylinder has a bottom pin of length 3 and a master wafer of length 2 in one chamber. What total lift must the master key provide in that chamber to reach the upper shear line?

  1. 2
  2. 6
  3. 5 Correct answer.
  4. 3

Explanation

The master key must lift the stack so the top of the master wafer reaches the upper shear line. That requires the combined height of the bottom pin plus the wafer, 3 + 2 = 5. The change key would lift only the bottom pin to the lower shear line.

Question 8General Locksmithing Knowledge

When rekeying a standard knob cylinder, what must be done before the plug can be removed?

  1. Insert the new key and turn the plug 180 degrees
  2. Loosen the strike plate screws
  3. File the bottom pins to the new bitting
  4. Remove the retaining cap or cam and withdraw the plug with a follower Correct answer.

Explanation

The plug is held in the shell by a retaining cap, cam, or similar retainer that must be removed first. A plug follower is then used to push the plug out while keeping the driver pins and springs from scattering. Filing pins or adjusting the strike plate is not part of plug removal.

Question 9General Locksmithing Knowledge

What does the term 'handing' describe on a lockset?

  1. The number of pins in the cylinder
  2. The finish applied to the lock trim
  3. The orientation of the beveled latch relative to the door swing Correct answer.
  4. The direction the key turns to unlock

Explanation

Handing describes whether a lockset is configured for a left-hand or right-hand door, based on which way the door swings and the latch bevel orientation. It is not about key rotation, finish, or pin count. Installing a lockset with the wrong handing causes the latch to bind or fail to secure.

Question 10General Locksmithing Knowledge

A rim cylinder is being installed on a night latch. What component transfers the cylinder's rotation to the lock body?

  1. The strike
  2. The tailpiece Correct answer.
  3. The rose
  4. The escutcheon

Explanation

The tailpiece projects from the back of the rim cylinder and engages the lock body to transmit rotation. The rose and escutcheon are trim pieces that cover the mounting, and the strike is on the frame. Without a properly sized tailpiece the cylinder cannot operate the lock.

Question 11General Locksmithing Knowledge

Which factor most directly determines the keyway profile that a blank must match?

  1. The cylinder's pin count
  2. The lock finish
  3. The door thickness
  4. The shape of the keyway warding in the plug Correct answer.

Explanation

The keyway profile is formed by the warding inside the plug, so the blank must match that cross-section to enter. Pin count affects bitting length but not the keyway cross-section. Door thickness and finish have no bearing on keyway profile.

Question 12General Locksmithing Knowledge

A key is cut with cuts that are too shallow, so the cylinder binds and will not turn. What is the most likely cause?

  1. The cylinder contains too many driver pins
  2. The strike plate is misaligned
  3. The tailpiece is too long
  4. The key was cut to the wrong bitting depth or spacing Correct answer.

Explanation

Shallow cuts leave key pins too high, so driver pins remain across the shear line and the plug binds. This points to incorrect depth or spacing in the bitting. Pin count, tailpiece length, and strike alignment do not cause a binding key in this way.

Question 13General Locksmithing Knowledge

What is the purpose of a plug follower during cylinder service?

  1. To measure the key bitting depth
  2. To align the cylinder in the door
  3. To keep driver pins and springs from falling out as the plug is removed Correct answer.
  4. To apply tension during picking

Explanation

A plug follower is inserted behind the plug as it is withdrawn, occupying the pin chambers so drivers and springs stay in place. It does not align the cylinder, measure cuts, or apply tension. Using a follower prevents lost or mixed pins during rekeying.

Question 14General Locksmithing Knowledge

A key operates the lock in one direction but will not withdraw after turning. Which condition is most consistent with this symptom?

  1. The key has a burr or the plug has a damaged key stop Correct answer.
  2. The key is a master key with the wrong bitting
  3. The cylinder has too few pins
  4. The door is hung with the wrong handing

Explanation

A key that turns but will not come out often has a burr catching on the plug, or the key stop is damaged so the key travels too far. Master bitting errors usually prevent turning altogether. Pin count and door handing do not cause a key to stick after rotation.

Question 15General Locksmithing Knowledge

Which of the following best describes a wafer tumbler lock?

  1. It uses flat wafers that must align with a slot to allow rotation Correct answer.
  2. It uses round pins driven by coil springs
  3. It uses levers engaged by a bit key
  4. It uses magnetic elements to align the shear line

Explanation

Wafer locks use flat, spring-loaded wafers that must be pushed to a common height so their edges clear the shell and allow the plug to turn. They are distinct from pin tumblers, lever locks, and magnetic locks. Wafers are common in automotive and low-cost padlock applications.

Question 16General Locksmithing Knowledge

What is the standard purpose of a strike plate on a door frame?

  1. To receive the latch or deadbolt and protect the frame Correct answer.
  2. To align the door within the jamb
  3. To reinforce the hinge side of the frame
  4. To cover the cylinder on the exterior

Explanation

The strike plate is mounted on the frame to receive the bolt and reinforce the jamb at the point of attack. Hinge-side reinforcement is a separate item, and cylinder trim is an escutcheon. Strike plates help secure the door rather than align it within the jamb.

Question 17General Locksmithing Knowledge

A customer wants a key that operates several different locks but does not want those locks keyed alike. What system meets this requirement?

  1. Keyed different
  2. Construction keying
  3. Keyed alike
  4. Master keying Correct answer.

Explanation

Master keying allows one key to operate multiple cylinders that each have their own change key, so the locks are not keyed alike. Keyed alike means one key operates all locks identically. Construction keying and keyed different do not provide a single overriding key.

Question 18General Locksmithing Knowledge

Which measurement is most important when selecting a replacement mortise cylinder?

  1. The color of the rose
  2. The cylinder length and thread size Correct answer.
  3. The brand of the door closer
  4. The number of keys supplied

Explanation

A mortise cylinder must match the door thickness and lock body, so length and thread size are critical for proper fit and function. Key quantity, trim color, and door closer brand do not determine whether the cylinder will install and operate correctly.

Question 19General Locksmithing Knowledge

What does the term 'shear line' refer to in a pin tumbler cylinder?

  1. The edge of the strike plate that receives the bolt
  2. The groove that guides the key into the keyway
  3. The gap between the plug and the shell where the pins must break Correct answer.
  4. The point where the tailpiece meets the cam

Explanation

The shear line is the boundary between the rotating plug and the stationary shell. When all pin breaks align there, the plug can turn. Keyway grooves, tailpiece joints, and strike edges are unrelated to this boundary.

Question 20General Locksmithing Knowledge

A locksmith is pinning a cylinder and finds that one chamber's spring is compressed solid when the plug is inserted. What is the most likely problem?

  1. The bottom pin is too short for the chamber
  2. The pin stack is too tall for the chamber depth Correct answer.
  3. The key is inserted upside down
  4. The plug follower was left in place

Explanation

If the combined pin stack exceeds the chamber depth, the spring is compressed solid and the cylinder will bind. The stack height must allow the spring room to function. A short bottom pin would leave the spring loose rather than solid, and the other options do not cause this symptom.

Question 21General Locksmithing Knowledge

Which of these is the correct first step when impressioning a cylinder to make a working key?

  1. Remove all driver pins
  2. Insert a blank, apply turning tension, and mark binding pins Correct answer.
  3. File all cuts to the deepest position
  4. Oil the cylinder heavily

Explanation

Impressioning relies on binding pins leaving marks on a blank under light turning tension; those marks guide incremental cuts. Filing all cuts deep or removing drivers defeats the method. Oil does not substitute for the marking process.

Question 22General Locksmithing Knowledge

What is the function of a cylinder's cam or actuator?

  1. It sets the depth of the key cuts
  2. It converts plug rotation into movement of the locking bolt or latch Correct answer.
  3. It holds the key pins in their chambers
  4. It seals the keyway against dust

Explanation

The cam or actuator is attached to the plug and transfers its rotation to the bolt, latch, or other locking mechanism. It does not retain pins, seal the keyway, or set bitting depth. A mismatched cam can prevent the lock from operating even when the correct key turns the plug.

Question 23General Locksmithing Knowledge

A door with a cylindrical lockset is sagging, and the latch no longer engages the strike cleanly. Which adjustment is most appropriate?

  1. Adjust or shim the hinges and strike to restore alignment Correct answer.
  2. Replace the cylinder with a longer one
  3. Change the key bitting
  4. Increase the pin count in the cylinder

Explanation

Sagging doors cause latch-strike misalignment, which is corrected by adjusting hinges or the strike, or by shimming. Cylinder length, pin count, and bitting affect security and keying, not door alignment. Fixing alignment restores reliable latching.

Question 24General Locksmithing Knowledge

Which statement about key bitting spacing is accurate?

  1. Spacing is the number of pins in the cylinder
  2. Spacing is the distance between adjacent cut positions along the blade Correct answer.
  3. Spacing is the width of the keyway
  4. Spacing is the depth of the deepest cut on the key

Explanation

Bitting spacing is the center-to-center distance between cut positions along the key blade and must match the cylinder's pin spacing. Depth refers to how deep each cut is, while keyway width and pin count are separate specifications. Incorrect spacing prevents the cuts from aligning with the pins.

Question 25General Locksmithing Knowledge

A locksmith must identify an unknown cylinder's keyway without a blank catalog. Which approach is most reliable?

  1. Compare the keyway cross-section against a known blank gauge or profile set Correct answer.
  2. Count the number of keys on the ring
  3. Test the lock with a tension wrench
  4. Measure the cylinder's overall length

Explanation

Keyway identification depends on matching the warding cross-section to a known profile, typically with a gauge or profile set. Cylinder length, key quantity, and tension testing do not reveal the keyway profile. Correct identification ensures the right blank is selected.

Question 26General Locksmithing Knowledge

What is the primary purpose of a deadbolt lock?

  1. To provide positive locking with a bolt that cannot be retracted by a simple latch slip Correct answer.
  2. To automatically relock a door when it closes
  3. To allow a door to be held closed while still permitting free passage
  4. To hold a door open at a fixed angle

Explanation

A deadbolt throws a solid bolt that has no spring-loaded bevel, so it resists being slipped or pushed back. It must be positively retracted by a key or thumbturn rather than by a closing action.

Question 27General Locksmithing Knowledge

Which tool is used to measure the depth of cuts on a key to determine its bitting?

  1. A key gauge or micrometer depth gauge Correct answer.
  2. A plug follower
  3. A pinning kit
  4. A caliper

Explanation

A key gauge or depth gauge measures each cut against the root of the blade to read the bitting. Calipers can measure dimensions but are not indexed to a key's cut reference in the standard way.

Question 28General Locksmithing Knowledge

What does the term 'backset' refer to on a lockset?

  1. The height of the lockset above the floor
  2. The distance from the edge of the door to the center of the bore or spindle hole Correct answer.
  3. The thickness of the door
  4. The length of the latch bolt

Explanation

Backset is measured from the door edge (or faceplate) to the centerline of the cylinder or spindle hole. It determines which latch and lock bodies will fit the prepared door.

Question 29General Locksmithing Knowledge

Which type of key is designed to operate a lock but is not intended to be duplicated by the end user?

  1. A change key
  2. A blank key
  3. A master key
  4. A restricted or patented key Correct answer.

Explanation

Restricted or patented keys are controlled through the manufacturer or authorized dealers so the end user cannot freely duplicate them. This control is a security feature of the keyway and key design.

Question 30General Locksmithing Knowledge

What is the purpose of a strike plate on a door frame?

  1. To mount the hinges to the frame
  2. To provide a reinforced opening that receives and holds the latch or bolt Correct answer.
  3. To cover the gap between door and frame for appearance
  4. To limit how far the door can swing open

Explanation

A strike plate is fastened to the frame and provides the opening that the latch or deadbolt engages, often reinforced to resist force. It protects the frame and helps align the bolt with the jamb.

Question 31General Locksmithing Knowledge

Which of the following best describes a mortise lock?

  1. A lock that is surface-mounted to the face of the door
  2. A lock that mounts through a large circular bore
  3. A padlock with a removable shackle
  4. A lock whose body is installed into a pocket cut into the edge of the door Correct answer.

Explanation

A mortise lock body sits inside a mortised pocket in the door edge, with the faceplate flush to the edge. This distinguishes it from surface-mounted and bored cylindrical locks.

Question 32General Locksmithing Knowledge

What is the function of a thumbturn on a deadbolt?

  1. To adjust the throw length of the bolt
  2. To lock the cylinder so a key cannot be inserted
  3. To tension the latch spring
  4. To allow the bolt to be thrown or retracted from the inside without a key Correct answer.

Explanation

A thumbturn provides an interior manual means to operate the deadbolt without a key. It is a convenience and egress feature on the inside of the door.

Question 33General Locksmithing Knowledge

Which component of a pin tumbler cylinder prevents the plug from being pulled out the front of the housing?

  1. The bottom pins
  2. The keyway warding
  3. The cylinder retainer or cap Correct answer.
  4. The driver pins

Explanation

A retainer, cap, or similar device secures the plug within the housing so it cannot be withdrawn from the front. Pins and warding serve different functions.

Question 34General Locksmithing Knowledge

A locksmith is asked to key a new lock to match an existing key. What is the first step?

  1. Determine the existing key's bitting by reading its cuts Correct answer.
  2. Install the lock on the door first
  3. Replace all the springs in the new cylinder
  4. Order a new key blank of a different keyway

Explanation

To key a lock to an existing key, the bitting must first be determined so the pins can be selected to match. Only then can the cylinder be pinned correctly.

Question 35General Locksmithing Knowledge

In a pin tumbler cylinder, what happens when the correct key is inserted?

  1. The springs push the plug outward
  2. All pin splits align at the shear line, allowing the plug to rotate Correct answer.
  3. The driver pins drop into the keyway
  4. The bottom pins are pushed above the shear line

Explanation

The correct key lifts each bottom pin so that every pin stack's split sits exactly at the shear line. With no pins crossing the shear line, the plug can turn.

Question 36General Locksmithing Knowledge

A locksmith needs to remove a plug from a cylinder but the plug will not slide out. Which condition most likely explains this?

  1. The keyway is too wide for the key
  2. The key is inserted and turned slightly, misaligning the pins
  3. The springs are too weak
  4. A retainer or set screw still secures the plug Correct answer.

Explanation

A retainer, cap, or set screw must be released before the plug can be withdrawn. Overlooking this fastener is a common reason the plug will not come out.

Question 37General Locksmithing Knowledge

Which factor determines the number of pins in a standard pin tumbler cylinder?

  1. The number of chambers bored in the plug and housing Correct answer.
  2. The length of the key blade
  3. The diameter of the keyway
  4. The thickness of the door

Explanation

The pin count corresponds to the number of chambers machined into the plug and housing. Each chamber holds one pin stack.

Question 38General Locksmithing Knowledge

A customer reports that a key turns in the lock but the door will not open. Which cause is most likely?

  1. The springs in the cylinder are broken
  2. The bolt is retracting but the door is binding against the frame Correct answer.
  3. The key is the wrong keyway
  4. The key has been cut too deep

Explanation

If the key turns, the cylinder is operating; the failure to open likely lies with the bolt, strike, or door alignment binding the bolt. This points to a door/latch issue rather than a keying problem.

Question 39General Locksmithing Knowledge

What is the purpose of a key blank's milling or shoulder?

  1. To provide a reference point for positioning the key in the key machine Correct answer.
  2. To prevent the key from being inserted upside down
  3. To increase the key's overall length
  4. To hold the key ring

Explanation

The shoulder or milling provides a consistent reference against which the key is positioned and cut. This ensures cuts are located at the correct spacing.

Question 40General Locksmithing Knowledge

Which of the following describes a 'change key' in a master key system?

  1. A key that operates only one lock in the system Correct answer.
  2. A key used only to remove the cylinder
  3. A key that operates the construction core
  4. A key that operates all locks in the system

Explanation

A change key operates an individual lock and not the others in the system. The master key operates multiple locks, including that one.

Question 41General Locksmithing Knowledge

A locksmith is pinning a cylinder and finds a chamber where the pin stack is too tall, causing the plug to bind. What is the most appropriate correction?

  1. Select a shorter bottom pin or adjust the stack to the correct height Correct answer.
  2. File down the driver pin
  3. Replace the spring with a longer one
  4. Remove the pin entirely from that chamber

Explanation

A stack that is too tall crosses the shear line and binds the plug, so the bottom pin length must be corrected to bring the split to the shear line. Springs and driver pins are not filed or removed to solve this.

Question 42General Locksmithing Knowledge

What does the term 'keyway' refer to?

  1. The slot in the strike plate
  2. The groove on the key head for the key ring
  3. The channel cut through the plug that accepts the key blade Correct answer.
  4. The opening in the door edge for the latch

Explanation

The keyway is the shaped channel through the plug that admits the key blade. Its profile and warding determine which keys will enter.

Question 43General Locksmithing Knowledge

A door closes but the latch does not fully engage the strike. Which adjustment is most appropriate?

  1. Replace the cylinder with a longer one
  2. Increase the spring tension in the cylinder
  3. Change the key bitting
  4. Adjust or reposition the strike plate to align with the latch Correct answer.

Explanation

Misalignment between the latch and strike is corrected by adjusting the strike or door position so the bolt enters cleanly. Cylinder and keying changes do not affect latch engagement.

Question 44General Locksmithing Knowledge

Which of the following best explains why a cylinder might be 'picked' open?

  1. Each pin is individually set at the shear line by applying rotational tension Correct answer.
  2. The springs are removed, allowing the plug to spin
  3. The keyway is widened to accept a larger key
  4. The driver pins are pushed entirely into the keyway

Explanation

Picking works by applying tension to the plug and manipulating pins one at a time until all sit at the shear line. This mimics the effect of the correct key.

Question 45General Locksmithing Knowledge

What is the function of the tailpiece or cam on a cylinder?

  1. To hold the key in place during insertion
  2. To secure the cylinder to the door
  3. To house the driver pins
  4. To transfer the plug's rotation to the lock mechanism Correct answer.

Explanation

The tailpiece or cam is attached to the plug and transmits its rotation to the lock mechanism, such as a latch or deadbolt. It is the linkage between cylinder and lock body.

Question 46General Locksmithing Knowledge

A locksmith must match a replacement key to an unknown keyway. Which approach is most reliable?

  1. Compare the key blade profile and warding against a key blank reference set Correct answer.
  2. Guess based on the key's color
  3. Measure only the key's overall length
  4. Try any key that fits loosely in the keyway

Explanation

Matching the blade profile and warding against a reference set identifies the correct blank reliably. Length alone or a loose fit does not confirm keyway identity.

Question 47General Locksmithing Knowledge

In a master key system, what does a 'master wafer' or master pin allow?

  1. The plug to rotate without any pins
  2. The cylinder to be removed without tools
  3. Two different keys to lift the same chamber to the shear line at different heights Correct answer.
  4. The key to be inserted in either direction

Explanation

A master wafer adds an intermediate split so that both the change key and the master key can align a shear line in the same chamber. This is the basis of master keying a pin tumbler cylinder.

Question 48General Locksmithing Knowledge

Why is it important to maintain correct pin chamber spacing when servicing a cylinder?

  1. Spacing controls the spring rate
  2. Spacing determines the door thickness
  3. Spacing sets the cylinder's overall diameter
  4. Spacing determines where the key cuts must align with each pin stack Correct answer.

Explanation

The distance between chambers must correspond to the key's cut spacing so each cut lifts its pin stack correctly. Incorrect spacing would misalign cuts and pins.

Question 49General Locksmithing Knowledge

A cylinder shows excessive 'key jiggle' and the key feels loose side to side. Which condition is most likely?

  1. The driver pins are too long
  2. The strike plate is misaligned
  3. The keyway is worn or the key is undersized Correct answer.
  4. The springs are too strong

Explanation

Loose side-to-side movement suggests a worn keyway or an undersized key blade. Spring strength, driver length, and strike alignment do not produce lateral key play.

Question 50General Locksmithing Knowledge

Which statement about a 'construction key' or construction core is accurate?

  1. It provides temporary access during building and is rendered inoperative when the owner key is first used Correct answer.
  2. It is used only to remove the cylinder from the door
  3. It permanently replaces the master key
  4. It operates only the deadbolt and not the latch

Explanation

Construction keys or cores allow access during construction and are designed to be disabled once the permanent key is used. This prevents construction personnel from retaining access.