The most common size has a casing that is 64mm in depth and the distance to the middle of the square operating spindle is 44mm. This size of the latch is used for most lever handles on back plates, where the width of the backplate is about 40-45mm.
Backset is measured from the centre of the keyhole to the edge of the lock. Most backsets are commonly measured at either 44mm (for a 64mm (2½”) lock) and 56mm (for a 76mm (3”) lock). Typically a lock adjacent to a glass panel will be 2½” (44mm) and otherwise 3” (56mm), but you should always measure to be sure.
In the United States, there are two common backsets for residential door locks: 2-3/8 inches. 2-3/4 inches.
There are two sizes of mortice locks: 21/2” and 3”. If you are installing a mortice lock to a door with a narrow frame, or any door for that matter, it's very important to know what size lock you need.
Determining the backset and overall length can be done by removing the existing latch and taking the dimensions. If the door handle or knob is still in place and you'd rather not remove it then you can measure from the edge of the door to the centre of the spindle hole (centre of the handle/knob).
Choosing Latches for your Door Handles or Knobs
The most common size has a casing that is 64mm in depth and the distance to the middle of the square operating spindle is 44mm. This size of the latch is used for most lever handles on back plates, where the width of the backplate is about 40-45mm.
The backset is the distance from the edge of the door to the spindle mechanism on the latch. Usually a 63mm case measurement will have a 44mm backset and a 76mm case measurement will have a 65mm backset. The backset you choose is where your door knobs will sit on the door (where the spindle goes through).
A pin-tumbler mortise lock is the most common type of mortise lock available. These Locks are very simple to operate and are fairly inexpensive. However, they are easily picked and are less secure than other types of locks. They are commonly found in older homes and apartments.
Mortise locks are installed into a rectangular pocket cut out of the edge of a door. The term mortise refers to a hole or recess cut that allows the lock to be inserted. Mortise lock bodies look much different than cylindrical locks and allow for more working mechanics inside.
Case depth is also a common main concern when it comes to sash lock size, with the two most common being 64mm (2.5 inches) and 76mm (3 inches) for 3 and 5 lever sash locks.
The diameter of the latch bore is generally 1” to accommodate bolts from either mechanical or electronic locksets.
It's important to note that a mortise latch and a tubular latch require two, very different door preparations. Tubular latches require 2 1/8” diameter cross-bores in the door, and 1” edge-bores. Mortise locks require a deep, rectangular pocket in the door.
The backset is the distance from the edge of the door to the center of the bore hole. There are two common backsets for residential door locks: 2-3/8″ and 2-3/4″.
Size of Mortise Locks
The common sizes of mortise locks are 65, 75 and 100 mm. The clear depth of the body shall not be more than 35 mm. The lock is capable of being opened with key from both inside and outside.
The two most common types of mortice latches include tubular mortice latches and standard mortice latches.
Mortise Latch
A mortise refers to the pocket cut into the door where the lock is fitted. Therefore, a mortise lockset cannot be installed on just any door. They are great for replacing the hardware on homes built before 1950. They can be used on new doors, but special preparations must be made.
Are mortise door locks universal? Yes, a mortise lock set and mortise door lock is universal and can easily be used to replace most other lock sets, especially on an older door.
When choosing your 5 lever lock, make sure it is stamped or kitemarked with BS3621 - this is a lock standard rating given by British Standards for thief-resistant locks. 5 lever locks are also generally sold in two sizes: 2.5 inch and 3 inch case sizes. These translate to 44mm and 57mm backset measurements.
Whether your lock is broken and needs replacing or you're just ready for an updated look, mortise locks are generally simple to remove and replace; standard mortise lock replacement parts made by Emtek, Juralco, Pado, Papaiz or new-style Wright are easily interchangeable.
However, you will find them very easy to handle and a joy to use. Now available in sizes 1/8" - 1/2" by 1/16". It is perfectly acceptable to just have one mortise chisel ( 1/4" or 3/8" being the most common) and size all your mortises accordingly.
It's essential that when fitting a mortice lock to an external door that you use a 5 lever lock for the highest level of protection. For internal doors, the use of 2 or 3 lever locks may be suitable as they generally don't need the same level of security as an external door.
Types of mortises and tenons
Haunched mortise. Open mortise. Stub mortise.
Firstly, What Is A Backset? The backset of a door lock gearbox if the distance from the front of the gearbox to the centre of the spindle hole as shown in the image below. The most popular backsets are 30mm, 35mm, 45mm and 55mm.
The backset is the distance from the edge of the door to the centre of the door handle. Please see the image below: Please note that our locks and latches mostly come in 44-46mm and in 57-60mm. 57-60mm is the standard backset.