Views: 0 Author: Site Editor Publish Time: 19-09-2025 Origin: Site
If you own an older home or commercial building, you're likely familiar with the distinctive look of a mortise lock. These locks, with their large, rectangular bodies set into a pocket (or "mortise") in the door's edge, were the standard for decades. While durable and secure, they can feel dated or become difficult to repair. This often leads to a common question: can you replace a mortise lock with a modern cylindrical lock?
The short answer is yes, but it’s not a simple one-for-one swap. Replacing a mortise lock requires specific steps and hardware to properly cover the large opening it leaves behind. This guide will walk you through everything you need to know about this conversion, from understanding the differences between the locks to the tools and techniques required for a clean, professional finish.
Before starting the replacement process, it's helpful to understand the fundamental differences between these two common types of door locks.
A mortise lock is a complete lockset system housed within a large metal case. This case is installed into a deep, rectangular pocket carved into the edge of the door. The system typically includes the latch, a deadbolt, and sometimes a switch or button to lock the exterior handle. Mortise locks integrate the handle and lock mechanism into a single unit, which is why you often see them with elegant, long faceplates (escutcheon plates) on the front and back of the door.
Key Features of a Mortise Lock:
· Integrated System: The lock body, latch, and deadbolt are all part of one large mechanism.
· Durability: They are known for being robust and long-lasting, often found in older homes and commercial buildings.
· Installation: Requires a deep, specific pocket cut into the door, making them more complex to install from scratch.
A cylindrical lock is the most common type of lock found in modern residential homes. Its name comes from the way the lock chassis is installed—by drilling two cylindrical holes in the door. One large hole is drilled through the face of the door for the main lock body and knobs/levers, and a smaller intersecting hole is drilled into the edge for the latch bolt.
Key Features of a Cylindrical Lock:
· Simplicity: The design is much simpler, with separate components for the lock mechanism and the latch.
· Easy Installation: Standardized hole sizes make them easy to install and replace.
· Versatility: Available in a vast range of styles, finishes, and security levels (e.g., Kwikset, Schlage).
While mortise locks are secure, there are several reasons why a homeowner or property manager might choose to replace one with a cylindrical lock:
· Availability: Finding replacement parts or a locksmith who specializes in older mortise locks can be difficult and expensive.
· Cost: A new, high-quality mortise lockset can be significantly more expensive than a standard cylindrical lock.
· Modernization: You may want to update the look of your doors with modern hardware that doesn't come in a mortise format.
· Smart Lock Compatibility: Most smart locks on the market are designed to fit standard cylindrical lock preparations, not mortise pockets.
Replacing a mortise lock is a multi-step process that involves removing the old hardware, preparing the door for the new lock, and installing a conversion kit.
Before you begin, make sure you have everything you need. This project requires more than just a screwdriver.
· Safety Glasses
· New Cylindrical Lockset (knob or lever style)
· Mortise Lock Conversion Kit (also called a wrap-around plate or door reinforcer)
· Measuring Tape
· Drill with a Hole Saw Kit (typically 2 1/8 inch for the main bore and 1 inch for the latch)
· Screwdrivers (Phillips and flathead)
· Wood Chisel
· Wood Filler
· Sandpaper
· Paint or Stain (to match your door)
Carefully remove the existing hardware.
1.Unscrew the Handles/Levers: Look for set screws on the side of the handles or levers. Loosen them to remove the handles.
2.Remove the Faceplates: Unscrew the long escutcheon plates from the face of the door.
3.Remove the Lock Body: On the edge of the door, you'll see the mortise lock's faceplate. Unscrew it, and then carefully slide the entire lock body out of the pocket in the door.
You will now be left with a large, rectangular hole in the edge of your door and holes on the front and back where the handles were.
The key to this project is a mortise lock conversion kit. This is a metal plate that wraps around the edge of the door, covering the old mortise pocket and providing a stable, pre-drilled surface for your new cylindrical lock.
1.Test the Fit: Slide the wrap-around plate onto the edge of the door. It should cover the mortise pocket completely.
2.Mark for New Holes: The conversion plate will have a pre-drilled hole indicating where the new lock should go. Use a pencil to mark the center of this hole on the face of the door. This is your guide for the main bore. You will also need to mark the center for the latch hole on the door's edge.
3.Drill the New Holes: Remove the plate. Using your drill and a 2 1/8-inch hole saw, drill the main bore through the face of the door. Then, use a 1-inch hole saw to drill the latch hole into the edge of the door, ensuring it intersects with the main bore.
The conversion plate will cover most of the old openings, but there might be some gaps or screw holes left exposed.
1.Apply Wood Filler: Use a good quality wood filler to fill any remaining holes or indentations from the old hardware.
2.Sand and Paint: Once the filler is dry, sand it smooth. Paint or stain the patched areas to match the rest of your door for a seamless look.
With the door prepped, you can now install the new lock as you would on any modern door.
1.Install the Latch: Insert the new latch bolt into the 1-inch hole on the edge of the door and secure it with screws.
2.Install the Lock Body: Install the exterior and interior sides of the cylindrical lock through the main bore and the latch mechanism.
3.Secure the Lock: Fasten the mounting screws to hold the lockset firmly in place.
4.Install the Strike Plate: Finally, align and install the new strike plate on the door frame. You may need to chisel out a new recess or fill the old one to ensure a perfect fit.
While this is a manageable DIY project for someone with the right tools and a bit of experience, there are times when calling a locksmith is the better option. If you are unsure about drilling into your door, if the door is particularly valuable, or if you want to ensure the highest level of security, a professional can handle the conversion quickly and correctly.
Replacing an old mortise lock with a new cylindrical lock is an excellent way to update your home's security and aesthetic. With the help of a conversion kit and the right tools, you can successfully bridge the gap between old-world hardware and modern convenience. By following these steps, you can give your door a fresh look while taking control of your home's security.
