Installing a mortised lock means fitting its lock case into a pocket in the door edge, then aligning the trim, cylinder (if used) and strike to that specific lock. There is no universal mortise size or installation sequence: identify the model and follow its instructions and template before cutting the door or frame.
What to check before installing a mortised lock
Start with the exact lock model and its supplied documentation. The case, faceplate, trim, cylinder, and strike all need to match the door preparation. A lock that is the wrong function or handing—or whose case and trim do not suit the existing openings—may not operate correctly even if it can be physically fitted.
- Confirm the lock’s function, handing, trim style, and whether it uses a cylinder.
- Identify the door material and compare its existing preparation with the manufacturer’s template.
- Check the case, backset, faceplate, and strike dimensions in that model’s documentation. Do not assume dimensions transfer between brands or models.
- Check whether the lock is mechanical, electronic, or electrified and follow the instructions for that specific version.
- Account for the parts supplied, such as the lock case, mounting screws, spindle and spring, spring cages, trim, armor front, strike, and dust box where applicable.
Schlage directs installers to compare the door preparation with the package template. Its PM Series installation instructions also state: “DO NOT USE POWER TOOLS for lock and indicator installation!” That warning applies to the PM lock and indicator installation described in that document; it is not a universal rule for every mortise lock.
Prepare the door and frame from the lock’s template
Use the template and instructions for the selected model to determine whether the door and frame are already prepared correctly. If preparation is needed, the template governs the lock pocket, faceplate recess, through-holes, and strike pocket. Confirm locations and dimensions before cutting or enlarging any opening.
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#1 Best Overall
- Ideal Use: Replaces worn or damaged mortise locksets on interior doors in older homes, restoration projects, and traditional residential settings
- Dimensions & Compatibility: Fits doors 1-3/8 in. to 1-3/4 in. thick; lock body measures 3-9/16 in. high x 3 in. deep x 1/2 in. wide
- Materials & Components: Durable steel mortise lock construction with bronze-plated finish and matching door knobs
- Key Features: Key-operated lock bolt functions from both sides and is compatible with both left- and right-hand door installations
- Fit Guidance: Verify door thickness, mortise pocket size, and lock dimensions before ordering; designed for mortise lock door applications only
Manufacturer documents illustrate why this matters. A separate ASSA ABLOY Modul lock instruction describes marking from its template, drilling to the specified lock-case depth, cutting a forend recess, and preparing the strike to its drawing. Its dimensions apply to particular Modul locks and strike hardware, not to mortise locks generally.
For Schlage products, the Schlage mortise-lock product page links to PM Series instructions and a template index. The template index separates door-preparation documents across mechanical, electronic, and electrified lock categories. Select the document for the exact product rather than relying on a generic mortise-lock layout.
Rank #2
- Built to Last: Crafted from rustproof zinc alloy and a reinforced steel core, this door lock withstands daily wear. Ensuring your mortise lock set interior door retains its vintage door knob elegance for decades. Perfect for homeowners seeking durable, low-maintenance hardware
- No-Hassle Installation: Replace outdated or broken hardware in minutes! The mortise lock set interior door comes pre-assembled with all mounting screws, spindle, strike plate, and a step-by-step guide. Compatible with both left or right-handed doors, simply flip the locking tab for universal fit
- Classic Security Meets Modern Convenience The dual-action skeleton key (included) operates smoothly from both sides, while the 5-pin cylinder mechanism prevents tampering. Use it as a privacy lock for bedrooms/bathrooms or to secure entryways
- New Match: This mortise lock set is ideal for 1-3/8 inch to 1-3/4 inch thick doors. Package contents 2*trim plates, 2*door knobs, 1*mortise lock body, 12*Mounting Screws, 1x 1/4" Square spindle, 1x strike plate and 2*Skeleton Keys
- Satisfaction Guarantee: If your vintage door knob or antique door knobs encounter issues, contact us via Amazon for free replacements or troubleshooting. Includes a 5-year warranty against defects, ensuring your old door knob replacement project is risk-free and future-proof
Fit the lock case, trim, and strike
Once the door preparation has been verified, follow the selected lock’s installation sequence. Do not apply one model’s trim order or dimensions to another. On Schlage PM Series escutcheon trim, the manufacturer’s procedure includes checking handing, fitting the chassis, installing the spindle and spring, assembling the outside spring cage and trim, fitting inside components and levers, installing a cylinder if applicable, tightening retaining screws, and fitting the armor front. The manual emphasizes spring-cage orientation and trim alignment.
- Set the handing. Check the instructions before fitting trim. For the Schlage PM Series, rotate the latch 180 degrees if needed and place the handing screw on the interior side of the chassis, as directed by its manual.
- Fit the lock case. Insert the case into the door-edge pocket and use the supplied mounting screws. For the cited PM escutcheon procedure, the chassis screws are left not fully tightened at this stage; follow the exact instructions for the lock you are fitting.
- Install the spindle, spring, and trim. Observe the specified orientation of spring cages and other orientation-sensitive parts. Align the trim as shown in the model’s instructions rather than forcing it into place.
- Fit the inside components and cylinder, if applicable. Use the correct parts and sequence for the trim and cylinder configuration.
- Tighten and complete the assembly. Tighten screws only at the stage directed by the manual, then fit the armor front and other included parts called for by that model.
- Install the strike and any associated parts. Position the strike according to the product’s template or drawing; do not substitute dimensions from another lock.
Test operation and correct alignment problems
Before considering the installation complete, operate the lock through its intended functions and check that the latch engages the strike without binding. Check the lever, escutcheon, and other trim for alignment. Do not force a stiff or misaligned mechanism; stop and compare the assembly with the model’s troubleshooting guidance.
Quick Recap
Best Value
- You will receive: 1 set double cylinder mortise lock, this right hand reverse mortise lock features a manual deadbolt for smooth, intuitive operation, designed for reliable access control with effortless locking and unlocking
- Standardized Dimensions: Suitable for entrance doors with a thickness range of 1-3/8 inches to 1-3/4 inches, with a rear size of 2-1/2 inches from the keyhole to the end of the door, and a panel size of 1 x 7-1/8 inches, the mortise lock set can be installed on most standard doors to save space
- Security Design: The double cylinder mechanism provides protection against forced entry, includes an additional night latch for reinforced security, offering peace of mind in residential or commercial settings
- Heavy Duty Steel Construction: Crafted from heavy gauge steel, this mortise lock set delivers exceptional durability and strength, built to withstand daily use while maintaining smooth operation over time
- Modern Style: The double cylinder mortise lock features an elegant polished brass finish that adds a contemporary touch to any door, combines sophisticated style with robust security performance
Rank #4
- Diverse use scenarios: Our mortise locks are suitable for interior or exterior doors. Bathroom, bedroom,living room ,dinning room etc. can bring comfortable experience.
- Size: Mortise Lock Set fit for door thickness 1-3/8" to 1-3/4" (35-45mm)，Please confirm the size data before buying.
- High quality and design:Exquisite design makes your home more elegant. The classic Matte Black finish mortise lock will be your excellent choice.
- Easy to install: Mortise lock set includes all parts for easy replacement of old mortise locks.
- After-sales: We will provide you with the best service, you can contact us with any questions, we will do our best to solve for you. Hope you have a pleasant shopping experience!
Rank #3
- MORTISE LOCK – This lock is designed for use on exterior entry doors, so you can enjoy the beauty of yesterday's vintage hardware with the strength of modern-day security hardware; includes a night latch for added security
- INSTALLATION – Easily install with all installation fasteners included; the left-handed lockset can be used on entry doors of 1-3/8 inch to 1-3/4 inch thick to match interior vintage style hardware
- DURABLE – The knobs of this lock set are constructed of diecast and reinforced steel components with a solid brass interior trim plate; the lock is finished with a beautiful satin nickel finish
- DIMENSIONS – This mortise lock has a 2-1/2 inch backset, 1-1/16 inch x 7-5/8 inch faceplate, 9/16 inch latch projection, 1 inch deadbolt projection, and has 2-1/4 inch in diameter knobs
- NOTE - Please refer to the line art drawing for dimensions and compare with your needs before purchasing (Not Universal)
- Operation is reversed: check the handing and handing-screw position against the instructions. Schlage’s PM Series troubleshooting links reversed operation to handing-screw placement.
- The lever or escutcheon gap is uneven: check the trim alignment. Schlage’s PM Series guide identifies missed alignment as a cause of this problem.
- The lock binds or the latch misses the strike: recheck the lock and strike alignment against the model’s drawings, and verify the case and trim are assembled in the prescribed order. Do not force the hardware.
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