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How to Mortise a Door Lock

This article is a collaborative effort, crafted and edited by a team of dedicated professionals.

Contributors: Muhammad Baballe Ahmad, Mehmet Cavas, Sudhir Chitnis, and Zhen-ya Liu.

✓ Verified & Tested Information

A mortise is a rectangular hole cut into wood into which a tenon, or tongue, is fitted to make a joint. A mortise door lock is a type of lock that uses this type of fitting.

Tools and Materials

Mortising is a woodworking technique used to cut a recess or pocket in a piece of wood. To mortise a door lock, you will need some specific tools and materials. The most important tool for mortising is a router with a mortising bit. You will also need a chisel and hammer, wood glue, wood screws, a marking knife, and a drill. Additionally, you will need to get the right type of door lock for the job. Once you have all the necessary materials, you can begin the process of mortising a door lock.

Gather necessary tools and materials

Before you begin mortising a door lock, it’s important to have all the necessary tools and materials. This might include: a marking tool, a drill, a steel chisel and hammer, wood glue, wood screws or bolts, a steady hand saw or jigsaw, quick-dry wallboard mastic cement or drywall adhesive, silicone caulk or sealant, and most importantly the door lock itself. The size of drill bit to use will depend on the size of the door lock as well as proper depth for screws/bolts used for attaching the door lock body. Additionally, if you intend to paint or stain your door frame after mortising the hole for your door lock body it is important to buy paint/stain which is suitable for use with wooden surfaces.

Check door and lock for compatibility

Before beginning any mortise installation project, you must make sure that the door and lock are in good condition and compatible with each other. You should measure the thickness of the door at the edge where you intend to fit the lock, then check that length against your chosen mortise lock. Mortise locks come in a range of lengths, and it is important to choose a lock that corresponds with the thickness of your door. If your chosent mortise lock is too short for your door, it will not sit properly in the cut when fitted.

You should also ensure that there is no existing hardware attached to or near where you plan to cut, such as hinges or door handles. If there are any existing fittings, which may interfere with your chosen mortise lock installation process, they should be removed before beginning work. It may also be necessary to sand down any rough edges around existing fittings if they interfere with the new mortise installation project.

Preparing the Door

Before you can install a door lock, it is important to make sure your door is properly prepared for the task. This includes measuring the mortise for the lock, drilling the necessary holes, and cleaning up the area so the lock fits properly. In this section, we’ll look at the steps you need to take to make sure your door is ready for the lock.

Mark the outline of the mortise

One of the first steps of mortising a door lock is to transfer the outline and depth of the mortise onto the door. This can be done using a piece of chalk or a marker. Take careful note to mark outlines for both halves if you are installing a two-piece system. Additionally, be sure to mark out any special cutouts for strike plates or latch bolts. Once the lines have been marked, it’s time to begin cutting!

Chisel out the mortise

Mortising the door for a lock is a task that requires accuracy and precision. Before beginning, ensure the correct size of chisels have been purchased for the job, as well as two corresponding drill bits – one to create the rough mortise outline and then a narrow bit to create the full recess.

Using the appropriate drill bit, make pilot holes along either side of where you want to chisel out the mortise, with each hole being roughly 1/16-inch smaller than what you want your final mortise width to be. It’s important that these pilot holes are positioned correctly in relation to each other on opposite sides of the desired mortise location. For example, if you need a 1/2-inch deep mortise you will drill two holes at 1/10-inch deep for your first pass with your chisel. The next step is to use a sharp chisel tool to connect these drilled out sections and remove material from between them until you reach your desired depth (1/2-inch).

Make sure not to insert the blade beyond your intended depth when using your chisel as it can easily cause gaps around edges of your finalized mortise cavity and weaken its structure when finally attaching it in place with lockset screws after drilling additional small screw pilot holes on either end. Additionally, be sure use appropriate striking force so as not to potentially dent or otherwise compromise door existing integrity. If necessary, lightly tap around perimeter of disturbed surface with an appropriate finish hammer and wood block combination where necessary body work has been performed in order complete job correctly while still helping maintain aesthetics of property’s entranceways.

Installing the Lock

Installing a door lock is a simple job that anyone can do with the right tools and a bit of patience. The first step when installing a door lock is to create a mortise. This is a cavity inside the door that the lock can fit into. It is important to take accurate measurements in order to ensure a secure fit. In this article, I will explain the steps involved in mortising a door lock.

Install the lock body

Once you have mortised the hole for your door lock, you are now ready to install the lock body. Here is what you’ll need: a drill with a saw attachment sized for the hole, screws, screwdriver, and washers.

Begin by attaching the screws to the lock body using your drill and screwdriver. Make sure that these screws are fitted tightly into their slots and not loose or over-tightened. Place two short washers onto one of each of the four larger holes in the lock body. Push them on so they sit snugly against the side surfaces of each hole.

Now insert your cutting machine into one of the larger holes in the lock body and use it to create two pilot holes in your door frame. Remove any debris created by drilling or sawing before continuing with installation. Next, feed two long screws through each of these pilot holes and secure them in place with a screwdriver until they’re tight enough to hold securely while still allowing space for movement during application and installation of other parts related to this doorlock system such as a cylinder or internal components.

Finally, carefully lower your doorlock body onto your mortised doorframe from above, making sure it is centered in its mortise without hitting either side walls too hard which could alter originally-planned positions of internal components like cylinders or latches. Once it is situated correctly into its own cutout pocket within mortise on frame, fasten all four screws with your cutting machine to finish assembly process as described earlier (adjusting washers if necessary). Your new doorlock should now be firmly installed!

Install the latch

Once the mortise is cut, install the latch by inserting it into the hole and securing it with screws. Most latch assemblies will include a strike plate for installation inside the doorjamb. You’ll need to measure its thickness and trim or chisel around the mortise so that there’s an even space all around. Make sure that this piece fits tightly enough in place so that it won’t rotate, as this could interfere with the function of the locking mechanism. It’s also important to align your latch flush with its edge so that it will fit snugly against your doorjamb when you shut the door. Finally, check that your door swings smoothly when shut before moving on to secure other components.

Install the strike plate

Once the mortise has been created, you can start preparing to install the door lock. Place the strike plate into position on the door frame, with the lips of the plate facing outward. If you are using a standard strike plate that is supplied with the kit, it will be pre-drilled for two wood screws. To ensure that alignment is perfect, use a combination square to make sure it’s horizontal and vertical in relation to the mortise. Then use a screwdriver or drill to secure it in place using the two wood screws provided. Make sure not to over tighten them as this could cause some misalignment later on. Once secure you can move on to inserting and fitting your door lock.

Finishing Touches

Once the mortise has been cut, the final touches must be completed to ensure the lock fits the door perfectly and functions smoothly. This involves chiseling and sanding the door frame to create a level surface for the lock to fit into. In addition, careful measurements must be taken to determine the necessary depth and angle of the mortise. Now, let’s take a look at the steps that need to be taken to finish off the mortise.

Sand and fill the mortise

Once the mortise has been cut, you can begin to dress it up to give it a more finished look. Using fine-grit sandpaper, smooth out the wood edges of the mortise. Sanding will help reduce the risk of splinters and make the door lock even easier to install. Next, fill any gaps or holes in the mortise with a wood filler that is recommended for use on doors and locks. Smooth out any excess filler and allow it to dry before continuing with installation. This step is important for ensuring a proper fit for your lock set.

Test the door lock

Before you complete assembling your door lock, it is important to make sure that the mortise hole is properly sized. To test fit the mortise, place the body of your door lock into the hole and secure it with a few short screws. Close the door and check for any gaps between the frame and strike plate. Make any necessary adjustments with a chisel and mallet before proceeding with installation. Once everything looks good, remove the screws from the body of your lock and fasten it into place with full-length screws.

Once you have installed your door lock, make sure to verify that all cylinders are still rotating freely. If there is any resistance or difficulty in turning them then you may need to adjust or replace some components of your door lock. Finally, once you are happy with all your adjustments, use a damp cloth to remove any excess sawdust from around the mortise area before closing up the door panel.

Make adjustments as needed

Now that the mortises have been cut, you will need to make any necessary adjustments. Check to ensure that the latch fits in the mortise properly, as an ill-fitted latch will result in poor security for your locked door. If the fit is overly tight or too loose, you may need to shave a bit off of the corners of your mortise with a chisel. Ensure that there are no splinters around the edges which could affect how smoothly the latch fits into its slot.

Finally, use a file or rasp to smooth any rough surfaces resulting from your work and provide a clean finish. Once you achieve a desirable level of accuracy and fit, slide your latch into place and test it out by locking and unlocking the door with both sides of your lockset. Make sure that it functions correctly before you drill screw holes for installation; otherwise, further adjustments could be required.

How to Mortise a Door LockCheckout this video:

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