Cylindrical knob locksets and mortise knob locksets differ primarily in their design, installation, and application. Cylindrical knob locksets are the most common type of lockset used in residential settings. They are relatively easy to install, requiring a hole drilled through the door for the knob and a smaller hole on the edge for the latch. The lock mechanism is housed within the knob itself. These locksets are generally less expensive and are available in various styles and finishes. They are suitable for interior doors or exterior doors with additional security measures. Mortise knob locksets, on the other hand, are more complex and robust, often used in commercial settings or high-end residential applications. They require a pocket, or mortise, to be cut into the edge of the door to accommodate the lock body. This type of lockset includes a separate lock body, knob, and trim, offering enhanced security and durability. Mortise locks can support heavier doors and are often used in situations where security is a priority. They also offer more functions, such as deadbolts and latch bolts, within a single lock body. In summary, cylindrical knob locksets are easier to install and more cost-effective, making them ideal for residential use. Mortise knob locksets, while more complex and expensive, provide superior security and durability, suitable for commercial or high-security residential applications.

1. **Gather Tools and Materials**: Screwdriver, tape measure, pencil, drill, drill bits, chisel, and the knob lockset. 2. **Remove Old Lockset**: Unscrew and remove the existing knob and latch from the door. 3. **Prepare the Door**: - Measure and mark the door edge for the latch plate. - Drill a hole for the latch using the template provided with the lockset. - Chisel out space for the latch plate to sit flush with the door edge. 4. **Install Latch**: - Insert the latch into the hole. - Secure it with screws, ensuring the beveled side faces the door jamb. 5. **Drill Knob Holes**: - Use the template to mark the door face for the knob hole. - Drill the hole through the door. 6. **Install Exterior Knob**: - Insert the exterior knob with the keyhole through the latch mechanism. - Ensure the spindle aligns with the latch. 7. **Install Interior Knob**: - Align and attach the interior knob to the spindle. - Secure with screws. 8. **Install Strike Plate**: - Close the door to mark the latch position on the door jamb. - Chisel out space for the strike plate. - Attach the strike plate with screws. 9. **Test the Lock**: - Ensure the door opens and closes smoothly. - Test the lock with the key to ensure it functions properly. 10. **Adjust if Necessary**: - Make any necessary adjustments to ensure smooth operation. 11. **Final Check**: - Ensure all screws are tight and the lock operates securely.

To rekey a knob lockset, follow these steps: 1. **Remove the Knob**: Insert the key and turn it slightly to the right. Use a wire tool or a paperclip to press the release button or pinhole on the knob shank. Pull the knob off the door. 2. **Extract the Cylinder**: Locate the cylinder retainer clip at the back of the knob. Use a flathead screwdriver to pry it off. Slide the cylinder out of the knob. 3. **Disassemble the Cylinder**: Insert the key into the cylinder and turn it slightly. Use a plug follower to push the plug out of the cylinder housing, keeping the pins and springs in place. 4. **Remove Old Pins**: With the plug removed, dump out the old pins. Keep the springs in their chambers. 5. **Insert New Key**: Insert the new key into the plug. 6. **Re-pin the Cylinder**: Use a rekeying kit to match new pins to the new key. Insert the correct pins into the plug chambers, ensuring they are flush with the plug surface. 7. **Reassemble the Cylinder**: Carefully slide the plug back into the cylinder housing using the plug follower to keep the pins and springs in place. Reattach the cylinder retainer clip. 8. **Reinstall the Knob**: Slide the cylinder back into the knob. Align the knob with the spindle and push it back onto the door until it clicks into place. 9. **Test the Lock**: Insert the new key and test the lock to ensure it operates smoothly. This process allows you to change the key that operates the lock without replacing the entire lockset.

Common problems with knob locksets include: 1. **Loose Knob**: This can occur due to frequent use. To fix, tighten the screws on the knob's faceplate using a screwdriver. If the screws are stripped, replace them. 2. **Misaligned Latch**: This happens when the door or frame shifts. Adjust the strike plate by loosening its screws, repositioning it, and tightening the screws. If necessary, enlarge the strike plate hole with a chisel. 3. **Sticking or Jammed Lock**: Dirt or rust can cause this. Apply a graphite-based lubricant to the keyhole and latch. Avoid oil-based lubricants as they attract dust. 4. **Key Won't Turn**: This might be due to a worn key or lock. Try a spare key. If the problem persists, lubricate the lock. If still unresolved, consider rekeying or replacing the lock. 5. **Broken Key in Lock**: Use needle-nose pliers to extract the broken piece. If it’s deep inside, use a broken key extractor tool. Avoid using the lock until the key is removed. 6. **Latch Won't Retract**: This can be due to a misaligned door or faulty mechanism. Check alignment and adjust the strike plate. If the mechanism is faulty, disassemble the lock, inspect for broken parts, and replace if necessary. 7. **Lock Cylinder Turns**: This indicates a loose set screw. Tighten the set screw on the side of the knob. If the problem persists, the lock may need replacing. 8. **Worn Out Lock**: Over time, locks wear out. If frequent issues occur, consider replacing the entire lockset for improved security and functionality.

1. **Remove the Old Lockset**: Unscrew and remove the existing knob lockset from the door to access the measurements. 2. **Measure the Backset**: Determine the distance from the edge of the door to the center of the hole (borehole) where the lockset is installed. Common backset measurements are 2 3/8 inches or 2 3/4 inches. 3. **Measure the Borehole Diameter**: Measure the diameter of the hole in the door where the knob is installed. Standard borehole sizes are typically 2 1/8 inches. 4. **Measure the Door Thickness**: Measure the thickness of the door. Standard door thicknesses are usually 1 3/8 inches or 1 3/4 inches, but some doors may vary. 5. **Measure the Latch Hole**: Measure the diameter of the smaller hole on the edge of the door where the latch is installed. This is typically 1 inch. 6. **Check the Strike Plate**: Measure the dimensions of the strike plate on the door frame to ensure compatibility with the new lockset. 7. **Note the Handing**: Determine the door handing by standing outside the door. If the hinges are on the right, it’s a right-handed door; if on the left, it’s a left-handed door. 8. **Select the Lockset**: Choose a replacement lockset that matches these measurements and specifications to ensure a proper fit. 9. **Consider Additional Features**: Decide if you need additional features like keyed entry, privacy, or passage functions based on the door’s purpose. 10. **Purchase and Install**: Buy the lockset that matches your measurements and install it according to the manufacturer’s instructions.

Yes, knob locksets can be used on exterior doors, but they are generally not recommended as the primary locking mechanism for several reasons. Knob locks are more vulnerable to forced entry compared to other types of locks, such as deadbolts. The locking mechanism in a knob lock is contained within the knob itself, making it easier for intruders to bypass by breaking or removing the knob. Additionally, knob locks can be susceptible to picking and bumping. For enhanced security on exterior doors, it is advisable to use a deadbolt in conjunction with a knob lock. Deadbolts provide a higher level of security because they extend deeper into the door frame and are not spring-loaded, making them more resistant to forced entry. A single-cylinder deadbolt, which is operated with a key from the outside and a thumb turn from the inside, is a common choice for residential exterior doors. If you choose to use a knob lock on an exterior door, ensure it is of high quality and consider additional security measures. These can include reinforcing the door frame, using a strike plate with long screws, and installing a security bar or door brace. Smart locks or keyless entry systems can also be considered for added convenience and security. In summary, while knob locksets can be used on exterior doors, they should not be relied upon as the sole security measure. Combining them with a deadbolt and other security enhancements will provide better protection against unauthorized entry.

To maintain and lubricate a knob lockset, follow these steps: 1. **Gather Materials**: You will need a screwdriver, a clean cloth, a non-abrasive cleaner, and a lubricant like graphite powder or a silicone-based spray. 2. **Remove the Lockset**: Use the screwdriver to remove the screws from the knob and the faceplate. Carefully take out the lockset from the door. 3. **Clean the Lockset**: Wipe the lockset with a clean cloth to remove dust and debris. Use a non-abrasive cleaner if necessary, ensuring no residue is left. 4. **Inspect for Damage**: Check for any signs of wear or damage, such as rust or broken parts. Replace any damaged components to ensure proper function. 5. **Lubricate the Lock Cylinder**: Apply a small amount of graphite powder or silicone-based spray into the keyhole. Insert the key and turn it several times to distribute the lubricant evenly. 6. **Lubricate Moving Parts**: Apply lubricant to the latch bolt and any other moving parts. Avoid using oil-based lubricants as they can attract dirt and cause buildup. 7. **Reassemble the Lockset**: Once lubricated, reassemble the lockset by reversing the removal process. Ensure all screws are tightened securely. 8. **Test the Lockset**: Insert the key and turn the knob to ensure smooth operation. Make any necessary adjustments if the lock does not function properly. 9. **Regular Maintenance**: Perform this maintenance routine every 6-12 months to ensure longevity and optimal performance of the lockset. By following these steps, you can maintain and lubricate your knob lockset effectively, ensuring it remains functional and secure.