How to Install a Mortise Lock – Step by Step Instruction

When it comes to security, mortise locks are one of the top choices of the users; however, installing a simple mortise lock is quite complicated. Therefore, even if you pick one of the best mortise locks from the market but don’t know how to install a mortise lock properly, it may turn out to be a waste of money.

To be honest, I have already made the mistake of not considering learning how to install it, and then the disaster happened. That’s why I feel it’s essential knowing how to fit a mortice lock in the doorknob before installation.

Although you are going to get mortise lock installation instructions as you purchase, I will incorporate all the essential details that only an experienced person can tell. Here, you will get an easy and straightforward mortise lock installation guide to follow for easy installation.


What Equipment You Need

Mortise locksets come with a unique mechanism.; thus, the installation process is complicated. So, to complete the installation process, you need to gather a few pieces of equipment. Find them below:

  • Chisel
  • Marker
  • Grit file
  • Mortise Lock
  • Door Clamp
  • Screwdriver
  • Measuring tape/ scale
  • Fixing equipment like the hammer, bradawl, drill bit, etc


Before you actually begin the lock installation process, there are a few things you need to check. First of all, the door you have chosen needs to be compatible to install the mortise lock. Note that all doors are not strong enough to take the pressure of this lock installation. If you are not sure about the door, you can ask any security expert. So, getting the right door is important. Otherwise, having a mortise lock on a weak door won’t ensure the security you are seeking.

Study the mortise lockset

The next point I would emphasize is to understand the lock. Because if you know how the mortise lock functions, then it would be easier for you to install it properly without any error. So, this lock comes with two main sections. One is the lock body, and the other is the lock trim. The lock body stays inside the door pocket. And the lock trim is attached along with it outside the door to operate the locking and unlocking feature.

Now, the lock body is a crucial part of this lock. This section comes with a mortise cylinder, latch, latch bolt, deadbolt/sash lock, and a spindle. The lock trim comes in a pair, which is installed on both sides of the door.

Since the lock body and lock trim are two independent sections, the spindle in the lock body is connecting the two elements to function locking and unlocking.

Overall, this is the basic mechanism of the mortise lockset. You may find more functionality in different locks. However, you will never find a mortise lock without a lock body and lock trims.

How to Install a Mortise Lock

Once you are ready with the equipment and a perfect door, brace yourself to start the process of mortise lockset installation. Here, for your help, I am going to explain each step in chronological order. You can combine one or two steps according to your convenience. However, I would prefer to explain each step individually in detail for a clear understanding of the mass users.

Now, let’s get started!

Step 1 – Steady door

First, you need to make sure the door stays steady. Since you are going to do a lot of hammering and drilling, ensuring the door to set in a strong and steady position is a must. To do that, you can put a wedge under the door and make sure it does not move.

Step 2 – Mark lock position and outline

The correct positioning of the lock is crucial. To avoid any error, you should mark the position where you want to install the lock on the door. Please put a mark for keyholes, strike plate, and latch on the side of the door. Usually, the professionals measure up to 36 inches from the bottom where the lock they set. Likewise, as you do so, put a mark using a marker where you will set the lock on the door side.

Now, position the lockset body on the marked section. As you see, the lock body comes in a rectangular shape. You need to make a perfect rectangular shape on the door accordingly. So, to make the outline, you need to place the lock faceplate against the door side following the marked position.

Now, create an outline according to the lock body. Here, while you are positioning the lock body, make sure you are properly holding it on edge. Also, using the bradawl, mark the keyhole that’s on the top and bottom of the lock faceplate. Additionally, it would be even better if you mark the timber, which you will need to remove to insert the lock body.

Step 3: Drill the keyhole

The next step is drilling the keyhole. While you are doing this step, you gotta be very careful and pay attention. As you have already marked the keyhole, you will drill right through it. But, there is a chance of damaging the door as well.

So, to avoid any accident or damage, you can clamp a wooden piece at the back of the door. The clamp will help to protect the door creating a perfect hole.

Step 4: Chisel the keyhole

A chisel is used to enlarge the keyhole. To do this job, you may need to use a hammer, drill, and chisel. Here, be careful to make the hole in the right size when you chisel.

Step 5: Drill the recess

It’s time to drill again. Now, you are going to create the recess. And, to do that, you need to choose a larger bit compared to the width of the lock housing. Usually, you will need a ⅝ inch auger bit for this job. Now, set the depth on the drill driver as much as your lock requires.

Here, make sure it’s deeper than the actual lock depth. Let me show you a trick! To know you are drilling through the right depth, you can put tape on the bit.

As you begin drilling, when you reach the end of the tape, you will stop drilling. The reason you are drilling deeper is that both the faceplate and the lock body will be recessed inside the door. So, for recessing, you may need to make several holes on the door side from top to bottom.

You may wonder why so many holes you need. Well, the purpose of creating a series of holes close to each other is to create a slot. Later, the lock receiver will fit in the right slot.

One tip I would like to share is when you are drilling, pay attention to the drill drive that runs parallel on the sides of the door. Otherwise, you won’t be able to set the lock straight in the hole.

Step 6: Chisel recess

As you have drilled the recess, obviously, you need to do the chisel. Like before, use a hammer and a chisel to remove the timber and debris and enlarge the hole slowly.

Step 7: Insert the lock and chisel the faceplate recess

So far, you have successfully made the door ready to insert the lock. When drilling and chiseling the recess is done, you need to insert the lock. Keep pushing the lock until you see the faceplate you see on the edge of the door. While you are trying the faceplate to show up, you may need to chisel the faceplate recess.

For this, you should mark the area where you need to do chiseling to remove the timber. Use the marker to mark the line, then use the same chisel and hammer to chisel the faceplate recess. Now, slowly remove the timber. Then, to smooth out the chiseled area, you can use a grit file.

Step 8: Secure the faceplate

Once you complete the insertion of the lock, you need to secure the faceplate. To secure it tightly, screw the faceplate slow and firmly. When you are doing this job, don’t forget to check if the keyhole position is correct. Otherwise, you would have a problem locking and unlocking the door using keys.

Step 9: Insert the keyhole covers

When lock body installation is complete inside the door, you need to set the keyhole covers. This process is very easy. You just need to fit the keyhole cover on both sides of the door as per the instruction.

Step 10: Mark the position of the receiver

To mark the position of the receiver, you need first to test the lock using the key. Leave the door open and turn the key back and forth. You will see the bolt comes out and goes in. When the bolt is out, close the door. It will touch the door frame on the wall. Then, you need to mark the bolt top and bottom parts on the frame. Here, you need to pay attention to marking the correct position. Then, again, you need to drill and chisel the marked section on the door frame.

Step 11: Set the receiver

Once you are done drilling and chiseling the receiving position of the lock bolt on the door frame, you need to set the receiver part as well. However, while you are inserting, carefully check the position, then secure it firmly with the screws provided.

Step 12: Insert the doorknob

Since different types of mortise locksets are available, some locks come attached to the plate. No matter what type of lock you have got, you need to insert the doorknob on both sides of the door. As I have already mentioned, the spindle connects the doorknob with the lock body; you need to connect them while inserting the doorknob carefully. Position the knobs parallel on both sides, then secure them with the screws provided.

Well done! You have completed the installation process!

Know More about Mortise Lock

Now you have known the easiest way to install a mortise lock. We hope you already have the latest one or you have just bought a new one. 

But if you haven’t bought it yet and want to compare the quality and price of some top products in the market, you can check the top 3 items below. 


So, how were the top three collections? Did you find yours? If yes, then congratulations! But, if not, then you have an option to compare more products before making the final decision. 

You can check out our top ten best mortise lock reviews with a handy comparison table.

Final thought

This is the overall process of installing an ideal mortise lock. I have followed this same process every time I had to do the mortise lockset replacement or insertion. You may follow more steps if you would like to, but I have tried to touch every detail that needs to be addressed to avoid any mistakes. Well, I have learned through experience and would love to learn from you too.

Don’t forget to share your tips and techniques about how you installed your mortise lock. 🙂

Yanao Jonson
Yanao Jonson

I am an avid fashion designer with a passion for making my house a home. I love to collect the necessary things of a home, and this is where I share with you my experience. I am currently working as the chief editor of I’d love for you to join me on my adventures!

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