Last updated on September 28, 2022 11:16 pm by the writer.
Bore hole size FAQs
Standard doorknobs require a 2-1/8 bore hole saw bit.
You need 1-inch hole saw bit to match the 2-1/8 inch standard bore holes.
Getting the perfect round shape
Hole saws are what I use for boring and cutting out perfectly round holes, the secret is a perfectly cylindrical-shaped saw blade on a drill bit ready for inserting into a power drill.
This type of drill bit is most commonly used for plumbing and electrical projects and is more efficient than flat and twisted drill bits for drilling large even-sized holes.
Hole saws are perfect for boring a hole for doorknobs since the bits will result in a perfect round cut through a door ready for your brand new doorknob or locking hardware.
So what size hole saw do you need for a doorknob? let’s find out.
What are things to consider when making a hole for door knob?
1. Main bore diameter hole
Check the diameter required for your door hardware like the doorknob and latches and find the appropriate door knob hole saw size. (Normal size listed next).
There are doorknobs that come in different sizes and diameters that might not fit into your existing doorknob hole.
The design of the door should be able to accommodate the diameter of the hole saw and the parts of the doorknob, to fit practically and aesthetically on the door.
2. Edge bore
It must also be able to fit perfectly perpendicular to the main borehole without damaging or making the door too thin and fragile to accommodate the latch.
The backset is 2-1/8-inch from the edge of the door to the center of the main bore. Have a few inches between the backset and the edge of the door to avoid difficulty during installation.
Depending on which backset you specify, your locks’ latch would have to fit. You should use a jig for the backset provided with the door hardware you are installing as each doorknob can be different.
4. Latch faceplate
A latch faceplate is the metal plate on the edge of the door that can be found next to the latch or deadbolt.
The latch face faceplate protects the lock from wear and tear.
It comes in different shape designs that would later be determined on the prescribed door preparation.
What size hole saw for a door knob?
1. For standard boreholes
The hole saw sizes for the standard doorknob is usually 2 ⅛ inches or 5.39 centimeters in diameter, being the larger bore compared to the edge bore to be made in tandem for installation.
When making the standard borehole for your doorknob, make sure to check the diameter of the hole saw and doorknob specifications to see if it fits with a 2 ⅛ inch standard hole saw bit.
Here’s how you can remove your doorknob.
If the hole saw size for the doorknob does not comply with 2 ⅛ inches, match the sizing of the hole saw to the doorknob as specified in the installation guide of the hardware.
You may also secure the drill bit with a jig for easier positioning and to double-check you have the right size hole saw.
2. For edge bore
The edge or latch bore, is generally 1 inch or 2.54 centimeters in diameter as a standard size, matching the standard main borehole of 2 ⅛ inches or 5.39 centimeters in diameter.
When making the edge bore, make sure to be perfectly perpendicular to the main borehole drilled in order to avoid any inconsistencies and issues during the installation of the doorknob parts.
Like the main borehole, match the sizing of the hole saw to the doorknob parts and the door, and you may also secure the measurement with a jig.
Always check with your hardware and chosen doorknob and door for installation and accurate sizing.
3. For deadbolts
A deadbolt or deadlock is a locking mechanism distinct from a spring bolt lock because a deadbolt can be only opened by a key or handle on one side of the door, having no knob.
As a standard, deadbolts usually need 2 inches or 5.08 centimeter wide boreholes, and a 1-inch or 2.54-centimeter spade bit for the sliding bolt assembly by the hole saw.
4. For stationary door levers
A lever door handle is where you push down on the lever to open the door, instead of twisting a knob handle.
To install a standard lever-type door handle, you need the same dimensions as standard doorknob boreholes, 2 ⅛ inches or 5.39 centimeters in diameter.
For the standard boreholes, and 1 inch or 2.54 centimeters in diameter for the edge or latch bore.
5. For keypad locks
A keypad can be considered a good middle ground between traditional keyed locks and fully connected smart locks which can be opened with a code entered on a touchscreen or a keypad.
The keypad can come at 2 ⅜ inches, which is about 6.03 centimeters, or 2 ¾ inches, which is about 6.98 centimeters, backset as needed to match any existing deadlock hole if possible.
6. For swinging handle sets
Handle sets are vertical handles that usually come as a pair, providing an elevated aesthetic.
As a standard, handle sets usually need a hole that is 2 ⅛ inches or 5.39 centimeters in diameter, with a backset of 2 ⅜ inches, which is about 6.03 centimeters, or 2 ¾ inches, which is about 6.98 centimeters.
7. For smart key locks
Smart key features re-key technology, which allows to re-key the lock in seconds for safety and convenience.
A smart key can usually replace a standard doorknob, following the standard size of 2 ⅛ inches or 5.39 centimeters in diameter.
Some smart key types of locks like what’s found in hotels would also need to handle some wiring and programming to have the technology up and running. But most operate on batteries for easier installation.
8. For dummy doorknobs
Dummy door knobs are mainly used for aesthetic and decorative purposes.
The handle will not lock or turn but can lock lightly in place with a spring.
Dummy door knobs can be installed by only drilling holes for the screws to be secured to the door. There is no need to bore out a large hole for internal mechanisms.
If ever there are boreholes on the door, 2 ⅛ inches or 5.39 centimeters in diameter like a standard doorknob.
Dummy door knobs are often used on wardrobe closets and held shut via a spring-type latch.
9. For thumb-turn locks
Thumb turn locks operate a deadbolt to lock or unlock the door from the inside, and are typically seen in bathrooms. This is also good for privacy.
To install a thumb turn lock, a large borehole like in standard door knobs is generally not needed.
You only need the screw part to be measured which can be made with a drill and its parts secured with screws.
The plate needs only the edge to be chiseled down.
Consult with the manufacturer’s instructions to see if there is a prescribed diameter.
How to measure the backset of your door?
To measure the backset on your door, check the distance from the outer edge of the door to the center, or highest point of the borehole.
If ever there is existing door hardware, measure from the edge of the door to the center of the knob’s backplate.
What to do if you have a metal door?
A hole saw is the most appropriate tool for installing drilling holes for doorknobs and even on a metal door.
Use a template from the lockset manufacturer. Mark the middle for the doorknob hole manually or use a jig. Drill a pilot hole with a ¼-inch bit perfectly and perpendicularly.
Use a 2 ⅛ inch hole saw with a fine blade made for drilling steel, aluminum, or stainless steel as you need.
Check you have a durable enough hole saw attachment for the metal so as to not blunt a blade made only for cutting wood.
First, cut through the metal cladding layer, then through the foam core, and lastly through the far side of the door’s cladding but drill from the other side to avoid tear-out.
For the latch, cut with a ⅞ inch or appropriately sized diameter hole saw or metal drill bit.
The standard size for doorknob
Hole saws are incredibly accurate and efficient I find for ensuring a perfectly circular hole in wood or metal on the building sites I work on.
Doorknobs need to be installed in a tidy fashion and you need to be reliant on tools and drill bits that provide evenness.
Hole saws come in different sizes for different project needs.
So what size hole saw for a doorknob?
Door knobs usually have a standard main bore size of 2 ⅛ inch or 5.39 centimeters in diameter, with an edge bore size of 1 inch or 2.54 centimeters in diameter to match.
Always check the specifications on the box from the manufacturer of the hardware you are installing.
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