3 lever locks are generally available in two standard case depth sizes: 2.5 inches (64mm) and 3 inches (76mm).
Measured from the centre of the keyhole/ cylinder to the centre of the follower hole (the square hole the handle spindle passes through).
You can work out the size of the lock by measuring the distance from the edge of the door to the centre of the door handle or knob. This measurement will give you the approximate size of the backset which will allow you to identify which size lock or latch you have.
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.
Sometimes 5 lever mortice locks are confused with the less secure 3 lever mortice locks. You can check this by looking on the faceplate of the lock, the number of levers should be stamped there.
3 lever locks are generally available in two standard case depth sizes: 2.5 inches (64mm) and 3 inches (76mm).
Grade 1 requires a key in knob must hold up to 300 lb-in and a lever lock must withstand 450 lb-in. Grade 2 requires a key in knob, must hold up to 150 lb-in and a lever must hold up to 225 lb-in. Grade 3 requires a key-in-knob to withstand at least 120 lb-in and a lever lock must withstand at least 180 lb-in.
In the U.S. there are two common backsets for residential door locks, 2-3/8" and 2-3/4". The backset is the distance from the edge of the door to the center of the 2-1/8" bore hole.
Lock Bore The diameter of the hole for the lock body. The standard bore is 2-1/8”. Many older doors had bores that were been smaller. Most of the current locks require the standard 2-1/8” bore.
We generally recommend that a 76mm Overall Latch Size is ordinarily the best size for most lever handles. However the shorter 64mm Overall Size should be used where the door is glazed, to minimize the risk of hitting the glass rebate when drilling to fit the latch.
The most common door prep uses a two and one-eighth inch cross-bore with a one-inch edge-bore. Another popular installation uses a one and one-half inch cross-bore with a one inch or seven-eighths inch edge-bore.
Generally, all you'll need to pick a lock are some picks (long, thin metal pieces with curved ends of different shapes for different types of locks) and a tension wrench. You can use paperclips as picks in a pinch, and a tension wrench can be any tool used to create tension, including a flathead screwdriver.
There are two sizes of mortice locks: 21/2” and 3”.
The difference between 3 lever and 5 lever mortice deadlocks
The more levers, the higher the level of security. Therefore, a 5 lever lock is more secure than a 3 lever mortice lock. It's also important to note that 3 lever locks are not BS3621 approved.
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.
A normal door lock is likely to be a mortice lock – either a deadlock, sashlock, euro sash case or euro deadcase style. These offer high security for external doors and also act as a visible deterrent because burglars know they're difficult to overcome.
Five-Lever Mortice Lock
This is an extremely secure lock and most used for external doors. They are usually approved by home insurance companies as front door or back door locks. They have more levers so are trickier to copy, keeping your home more secure.
Any time you replace exterior door hardware, it is helpful to know your keying options. Most exterior locks purchased in-store come with a unique key. That means if you purchase multiple exterior locks at once, they will each have a different key required for access. This can be a hassle.
7-, 8-, and 10-pin tubular locks have the same keyway size, but a different number of pins. Even though the keyways are all the same size, the spacing of the pins is different. This is why you'll need different tubular lock picks to handle different locks.
A lock's security is denoted by its American National Standards Institute (ANSI) grade, with Grade 1 the most secure and Grade 3 the least. A builder-quality tubular lock will likely be a Grade 3, a good-quality handleset a Grade 2.
Schlage and Kwikset are two of the most popular lock manufacturers on the market. Both brands make excellent locks that homeowners can easily install, but Schlage locks tend to offer higher security and reliability and are trusted by big businesses.
Lever locks aren't immune to picking. There are special lockpicking tools designed to pick the lever locks. Known as a curtain pick, it's inserted into the keyhole. When pressure is applied to the curtain pick, it's able to move each of the levers into the appropriate position.