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The Parts Of A Door Knob: Assembling A Door Knob

If you want to replace your old door knob or repair the existing one, it helps to know the various components that make up its assembly. No matter how simple it appears on the outside, a door knob consists of several parts that all work together to form a secure point between the inside of your home and the outside world.

At Access Residential Hardware, we sell door knobs that range in complexity from traditional knobs and levers to modern keyless solutions. There are two main types of locks manufactured today: mortise locks and cylindrical locks. In this blog, we list the parts of a mortise lock and cylindrical locks and explain each one’s contribution to the entire assembly.

Mortise Lock

A mortise lock is installed into a rectangular pocket cut into a door edge. A mortise is a hole or recess in which the lock is inserted. Compared to cylindrical locks, mortise locks have a distinctive look and are equipped with more working mechanisms. They also have more trim and lever styles, resulting in greater design flexibility.

Lock Body

The lock body is the metal case that houses the lock mechanisms for a mortise lock. The lock body, which is shaped like a letter T, is slid into the door and protects the lock components. Upon looking at the door from the front, you will notice the body’s square section attached to the door facing. There are parallel vertical sections on the left and right that fit into rectangular holes cut into the jamb.

Mortise lock bodies can accommodate standard locking functions as well as deadbolts, thumbturns, indicators, and other options. This makes them versatile. There are over 49 functions available on Schlage mortise locks, compared to over 29 functions for Schlage cylindrical locks.

Deadbolt Knob

The deadbolt knob controls the deadbolt. Rotating the knob toward the closest edge of the door engages the deadbolt, while rotating it in the opposite direction disengages it.


The spindle is the square bar that connects to the handle or knob and passes through the spindle hole on the mortise lock. The spindle operates the latch bolt when the knob or handle is turned.


There are usually two springs built into mortise locks. One spring pushes the latch bolt out, so it can remain locked in the strike plate. The other spring pushes the lever down to keep the deadbolt locked into place.

Interior Knob/Handle

The interior door knob or handle controls the latch bolt from the inside. When the knob or handle is turned, the spring retracts allowing the latch to be pushed into the door.

Lock Buttons

Lock buttons are installed on the side of the door in the faceplate and can be used to control how the door functions. When the top lock button is pressed, the outside knob won’t turn, but the inside knob will. This allows the door to be unlocked from the inside with the turn of the knob or lever while the exterior knob or lever would require a key.


The faceplate is a metal plate that is mounted to the edge of the door. The faceplate helps to protect the latch, lock buttons, and deadbolt.


The deadbolt is the lock bolt that is engaged by turning the deadbolt knob. The deadbolt provides added security, because it can’t be battered or bored easily.

Latch Bolt

The latch bolt is the bolt that springs out of the door and locks into the strike plate when the door is closed.

Strike Plate

The strike plate is a plate that is mounted to the doorframe. The strike plate protects the door jamb and connects with the latch-tongue and deadbolt to keep the door closed.

The strength and reliability of mortise locks make them a popular choice for commercial spaces, but they’re equally appropriate for busy homes. Additionally, the internal mechanisms are easily replaceable and serviceable, which is helpful for new homeowners.

Repairing a Full Mortise Lockset

Remove the set screw holding the key cylinder in place. In most lock bodies, this is found on the jamb-side, closest to the keyed side of the cylinder. Remove the screws holding the thumb turn to the door and remove the thumb turn as well. The cylinder should come loose.

The door knob is attached to the lockset by a set screw. Remove the set screw and the doorknob will come off. After taking off the exterior half of the door knob and the shaft that passes through the lock, remove the entire mortise lock body.

Remove the screws holding the cover to the lock body. Inspect the interior for worn, broken, or loose parts. Carefully remove the damaged or worn pieces and take them to a locksmith shop for replacement. Once you’ve obtained them, use the new parts to reassemble the lock body. Reattach the cover and screw it in place.

Before inserting the reassembled lock body, check the door for damage. Years of continuous locking and unlocking can wear down older doors, so fill any stripped screw holes with wood putty. Re-drill the holes after it has dried.

Reinsert the lockbox into the door but leave it loose. After threading the lock cylinder into the lock body, tighten the set screw on the jamb side of the lockbox. Then reinstall the thumb turn on the inside of the door before putting the exterior door knob back on by sliding the shaft through the lock body. Attach the interior door knob to the shaft and tighten it.

Cylindrical Lockset

Cylindrical locksets have rounded mechanisms that attach to the latch bolt. They are mainly used for interior doors and do not include a deadbolt. With cylindrical locks, the latch retracts when the knob or lever is turned or depressed on either side.

They have the advantage of being relatively easy to install. You only have to drill two holes through the door- one through the face for the lock chassis and the other through the strike edge for the latch bolt. The installation of cylindrical locksets takes less time since no mortise pocket has to be drilled and chiseled.

Interior Knob/Handle

The interior knob or handle is the component you twist or pull down on to open and close the door from the inside of a room. The interior knob or handle contains the lock button if the hardware is for a privacy door knob or door handle.


The spindle is the square bar that connects both knobs or handles, so that they turn together. The spindle rotates when a handle or knob is rotated to retract the spring bolt and allow the door to open.


The shank is the projecting stem of a door knob or door handle that contains a socket to receive the spindle.


Door knobs or handles are often built with slots on the neck. Slots can be used to remove a door knob or handle without a latch.


The rosette is the plate that covers the mounting plate. Rosette plates serve two purposes: they protect the internal mechanisms of the door knob or handle, and they provide a decorative element to make the knob or handle look good on the door.

Mounting Plate

The mounting plates secure the two door knobs or handles together with the cylinder through the door bore hole.

Spring Clip

The spring clip is a spring mechanism that pushes the bolt of the latch outward. The spring is retracted when the knobs or handles are turned.

Lock Button

The lock button could be a button, but it can also be a thumbturn. When the button is pressed or turned a deadlatch is released, which keeps the door securely locked.

Latch Assembly

The latch assembly is a spring-loaded bolt that holds the door closed. The spring clip forces the bolt outward so that it stays locked in the strike plate until the spring is retracted.


The faceplate is a metal plate that is mounted to the edge of the door. The faceplate helps to protect the latch and hold it in place.

Strike Plate

The strike plate is a plate that is mounted to the doorframe. The strike plate protects the door jamb and connects with the latch-tongue to keep the door closed.


The cylinder is the exterior housing of the cylindrical lockset that houses the locking mechanism. The cylinder sits inside the bore hole of the door.

Exterior Knob/Handle

The exterior door knob or door handle is identical to the interior door knob or handle. The only difference is that this component is on the other side of the door facing the exterior hallway or room.

Repairing a Cylindrical Lockset

If you decide to repair the lock yourself, locate the bore and lockset on the inside part of the door. There may be several set screws, but usually there is one above and one below the latch. Make sure the screws are stored safely, so they don't end up lost.

With the screw out, you can now completely unlock the door with the current key. Turn the key a 1/4 turn to completely hide the latch. Using this method, you can slide out the entire key cylinder, including the latch. As you pull on the key, push on the opposite end of the cylinder with your hand, leaving the key inserted in the cylinder. It should be easy to remove. If it does not, try turning the key again. The latch may not be completely inside.

Check for and remove any broken parts. After you’ve purchased and installed any replacement pieces, insert the key in the lock, and slide the new cylinder back into the hole. The key needs to be turned just enough to release the latch into the door and secure the cylinder. Most of the time, this only requires a quarter turn. Make sure the new cylinder is working properly by turning the key as if it were locked before closing the door. You should be able to see the latch sticking out. Then replace the screw.

We Have Door Hardware for All Homes and Budgets

Understanding what lockset you have and its various components makes it easier to determine when you need to replace a part or even the entire assembly. At Access Residential Hardware, we sell mortise locksets and cylindrical locksets from leading brands Like Baldwin, Emtek, LCN, Schlage, and Yale. Whether you’re looking for an elaborate vintage theme or something more streamlined and modern, we have the door hardware that meets your needs.

If you have questions about our products or need a recommendation, we’re here to help! To speak with one of our representatives, please call 866.752.9002, or fill out this form and we’ll get back to you shortly. We look forward to assisting you with your door hardware needs.