Installing a combination door lock means matching its body, cam, and latch to your door’s holes, then setting and testing the code before closing the door.
Most mechanical combination locks mount from the exterior side, pass a barrel or spindle through a pre-drilled cutout, and fasten with screws or mounting nuts on the opposite face. The exact hole sizes and cam selection are model-specific, so the smart move is to confirm the door’s thickness and bore size before you begin.
What You Need Before Starting
The manufacturer’s cardboard template and the lock’s manual are the two most valuable tools on the bench. Reputable installation sheets, including Sargent & Greenleaf’s instructions, all repeat the same advice: use the template, drill only the specified holes, and test before closing the door.
You will need:
- A drill with the exact bit sizes your model calls for — many digital locks spec two 4.5 mm (3/16″) holes plus one 16 mm (5/8″) hole.
- The correct cam, stop cam, latch, or tailpiece for your door’s hand and thickness.
- The supplied screws, nuts, or mounting hardware — never substitute parts.
- A pencil, a Phillips screwdriver, and a tape measure.
One keypad lever lock manual requires a standard 2-1/8″ bore hole with a backset chosen before drilling. The SIMPLEX 7106 series goes further, recommending the exterior thumbturn sit at least 7 inches above the primary lockset and a minimum stile width of 4 inches (102 mm).
Drilling and Mounting the Lock Body
Hold the template against the door at the height you want, mark every hole location, then drill the specified sizes. Drilling without the template is the most common mistake called out across installation manuals — edge positioning errors are nearly impossible to repair cleanly.
Working from the exterior side, insert the lock body through the door cutout. The front and back parts must stay paired as they arrived; mismatched pieces will not function even if they look identical. Choose the cam or latch matched to the door and frame now, not after the lock is screwed tight.
Securing tip: attach the correct cam for the door’s handing, then secure the assembly with the supplied mounting hardware. If anything resists aligning flush, stop and check the cam orientation — forcing the mechanism is a classic cause of jamming. Sargent & Greenleaf’s installation instructions spell out the pairing and alignment requirements in detail.
Setting the Combination and Testing
Change the default code immediately and keep the door open while you verify operation — closing it before you confirm the mechanism works is how lockouts happen. The procedure varies, but the rule is consistent: set the combination only after installation is complete and the lock functions smoothly.
Test the lock at least five full cycles with the door open:
- Enter the new code and confirm the latch retracts fully.
- Close the latch manually and repeat.
- Test from both inside and outside where the design allows.
- Verify the thumbturn or handle operates without binding.
If the mechanism hangs or the bolts drag, remove the interior plate and recheck the cam alignment before the door goes into service. Once everything moves cleanly, the heavy-duty levers, and a few all-weather models, our tested roundup of the best combination locks for front doors compares the top picks side by side.
FAQs
Do all combination door locks fit standard doors?
No. Mechanical combination locks group into two fitting classes: replacement deadbolts that swap into a 2-1/8″ bore hole, and surface-mount or specialty locks that adapt to doors without existing prep. Check the door thickness and backset in the manual before buying.
What happens if I mix parts from two locks?
The lock will not function. Manufacturers pair each front and back assembly at the factory, and the tolerance between internal cams and drivers is tight enough that mismatched pieces bind or fail quietly. Keep each lock’s parts together and label them if you install multiple units.
Why does my combination lock stop opening after installation?
Unfasten the interior plate and re-read the cam orientation section of your manual. The second most common cause is a screw over-torqued into the latch, which pinches the mechanism.
References & Sources
- Sargent & Greenleaf. “Installation Instructions 2890B.” Details cam pairing, alignment, and test-before-close requirements for mechanical combination locks.