This post will show you how to fit a round door knob lock on an internal door with a step by step photo and video guide. It will also show you how to drill your door accurately for the latch holes and also how to drill the door frame for the strike plate fitting.

We needed to fit a door knob on our bathroom door to match the rest of the doors in our house. So we searched for a gold colour door knob and found a decent lock on eBay manufactured by Era. You can also buy these Era door knob locks from Screwfix. 

The door knob came with all the fittings, instructions and also door drilling template. The template was really useful to figure out exactly where to drill, but with a little amount of patience, you can also do it without a template.

What was in the door knob lockset package:
Door knobs
Latch
Keep / strike plate
Dust pocket (to go inside the keep)
Screws for the latch and strike plate
Screws for the door knob
Instructions and template
Keys (optional, you can go for door knobs with no keys, but we went for locking function as it was for the bathroom so you could lock it from inside too)

Fitting the door knob on the door

This whole process of fitting the round door knob lock on our internal door took just under 2 hours. You do not need many tools, however, if you are fitting this lock on a brand new door or a door that does not have pre-drilled holes suitable for a round door knob style lock, then you will need a drill with hole saw bits. 

Tools you need to fit a door knob:

Here is a list of tools you will need to fit the round door knob lock on your door by yourself DIY:

Combi drill
54mm holesaw
25mm holesaw
Carpenters square/speed square
1-2cm width wood chisel
Hammer/mallet
Philips screwdriver
Sharp pencil

How to fit a door knob – full step by step guide video

If you’d rather watch a video of the whole process, then here it is:

Step 1: Drilling the door for the latch hole

This step is very important to get right with very accurate measurements.

If you look at your latch, you will notice that the latch can be adjusted so the stem hole location is either 60mm from the edge of the door or 70mm.

This depends on the door knob you may end up purchasing and the brand etc but generally, this depth decides how far your door knob will be from the edge of the door eventually.

After you have decided the depth of your latch, you will have to decide the exact position on the door you want your door knob to sit on. To do this, simply decide the vertical position or height of the door handle first. Usually, your door knob will be vertically centred on the middle rail of a wooden door as shown in the picture below. 

Once you find the centre point on the middle rail of the door, you can use a carpenter’s square/speed square or a combination square to draw a straight line from the edge of the door as shown in the picture above.

Using the template that came with your door knob, as shown in the picture above, align the main horizontal line on the template with the line you have just drawn on your door. Then using your pencil, mark the centre point of the lock set hole on the template and apply enough pressure so your pencil penetrates the paper and leaves a mark on your door. 

This pencil mark is exactly where you will need to position your 54mm holesaw to drill the main hole where your door knobs and the latch will meet.

Drilling the main latch hole on your door

Once you are ready to drill the 54mm hole, make sure to hold the drill as level/adjacent to the door as possible. 

It is recommended that you do not drill through all the way from one side to prevent splitting. So once you see the drill bit starting to poke out on the other side of the door, as per picture below, it’s time to switch to the other side of the door. 

Using the hole on the other side of the door as your starting point this time, repeat the process from the other side of the door until you are fully through the door with your circular cutting blade.

Step 2: Drilling a 25mm hole on the door edge for latch

This hole is the 2nd of the 3 holes you will need to drill as part of this DIY door knob fitting project! Almost there. 

As you can see from the picture above, we will need to drill a hole on the side of the door for the latch to go through and meet the door knob at the centre of the main latch hole we drilled earlier.

For this, you will need to drill a hole exactly at the centre of the door face on the side, on the same level line as the first latch hole. You can simply measure the width of the door as per picture above, and then halve it.

We used a 25mm holesaw for this as per the instructions that came with this particular door knob.

The above picture shows what your door would look like when you are done drilling both 54mm and 25mm latch holes that intersect with each other.

Step 3: Chisel a rebate for the latch on door

So the latch sits fully flash/flat against the surface of the door, we will need to chisel 2 to 3 mm rebate depending on the thickness of your latch face plate. Insert the latch through the newly drilled hole and hold it parallel to the door face. 

As shown in the picture above, mark the outline of the latch face on the door and then remove the latch.

Using the wood chisel, carefully chisel away a 3mm deep rebate. 

You will need to take extra care when you are chiselling the rebate. The door may split on the sides very easily if you apply too much force. 

To get the depth of thickness correct, stop often and fit the latch in the hole to check if you are on track. It is recommended that you sharpen your chisel beforehand to avoid splits. It is also a good idea to minimise the use of hammer for tapping unless you are confident that you can control the force and angle etc.

Additionally, it is also recommended that you check the depth often by fitting the latch to avoid ending up with a deeper rebate than necessary. 

Once you are happy with the rebate, it’s time to drill pilot holes for the screws that will hold the latch in place. Pilot holes are highly recommended as this will ensure the door does not split, especially considering that this region of the door may be compromised already – from previous drillings and chiselling.

Find the appropriate drill bit size according to the screws that came with your door knob package. Then mark the hole positions.

Once the pilot holes are done. You are ready to fit the latch and the door knob on your door! 

Step 4: Fitting the door knob and latch

Before you go ahead and attach the screws for the latch and also assemble the door knobs, it will be a good idea at this point to carry out a dry fit test.

Insert the latch into the side of the door.
Then proceed with inserting both door knob handles from each side of the door.

Holding all 3 pieces in place with one hand, twist the door knobs with the other hand, interchanging hands to check both sides. Ensure that the lock lever moves freely without catching and everything feels right. 

Once you are happy, go ahead and screw the latch on the door securely. It is recommended that you use a phillips head screwdriver to manually drive the screws in. Please take extra care not to over tighten the screws, because, as you may have guessed it already, it may split the door!!

Once the latch is attached, you can fix the door knob screws next. The two screws that your door knob package will come with, will attach the two door handles together through the door. 

You will be able to reach the screws without removing the door knob cover. If you find it difficult, you may be able to remove the door knob cover so you can access the screws easier. Follow the manufacturer instructions for your particular door knob if this is needed.

Step 5: Fitting the Strike plate on door frame

Now that the door knob and the latch are fitted already on the door, all you have to do is fit the strike plate on the door frame and we are done. The tricky part in this step is to find the exact position of the strike plate on the door frame. This is so that you know where to drill on the door frame so it’s perfectly aligned when the door is shut for the lock lever to slot into.

However, as we all know, there aren’t many problems in wood working that can’t be solved with a pencil and a carpenter’s square! 

Start by holding the door shut i.e. in the position where you expect the door to be when it is completely shut. Now if you remember back in step 1 earlier, we marked the horizontal line on the middle door rail, see picture below.

Extend this line with a pencil on to the door frame. 

This will give you the vertical position or y axis value of the centre point of your strike plate drill hole.

Repeat the same process for the latch plate and transfer the top and bottom position from the door to the frame as shown in the picture above.

Then carry the marks over to the inside of the frame (or jamb) to locate the centre of the frame where the lock lever will strike / penetrate the frame. Finally, measure the width of the recess of the frame, which should be the same width as your door. Divide the measurement by two, and then you will find the centre point where you will need to drill one last time.

Using your 25mm holesaw that you used earlier in step 2 above to drill through the door for the latch fitting, drill another hole at your marked position for the lock lever to meet the strike plate. 

Drill to a depth of about 25mm to accommodate the full protrusion of the lock lever. Remove the holesaw bit once you reach the 25mm depth. There is no need to remove the circular piece of remaining wood in the frame just yet. This will come off once you start chiselling around it as per the size of the plastic dust pocket as shown in the picture above.

The final step in fitting the strike plate is to chisel a rebate onto the door frame or jamb so that the strike plate can sit flat on the frame without catching the door. To do this, we will repeat the chiselling steps similar to step 2. 

Place the strike plate exactly on the marks you transferred earlier from the door on to the frame. Then with a pencil, mark the outline of the strike plate on the door frame or jamb as shown in the picture above.

Using the wood chisel, carefully chisel a rebate approximately 2mm deep. Please take extra care when chiselling around the corner of the jamb. Test fit the strike plate and adjust the depth as you go until it is completely flash against the frame. 

The final step is to mark the screw position, drill pilot holes and you are done!! This is it. You have fitted a door knob on a door with no pre drilled holes or a strike plate in the frame! 

We hope you found this article useful. It isn’t simple or easy to drill latch holes on a door or strike plate on the frame for any door locks, let alone the round door knobs. Therefore, we tried to be as thorough as possible with all pictures and illustrations to help you understand the exact process of fitting a round door knob handle on a door. If you have any suggestions, comments or tips you’d like to share, then please leave a comment below. Once again, thanks for stopping by and speak soon!