I am trying to change a door knob but first I need to remove the lock. There seems to be a kind of nail that is visible on both sides of this piece (see pictures), but it is stuck. I tried to hit it gently with a hammer and another nail to push it from the side where the head is smaller but it does not work, it is still stuck.

How can I remove this and which tools do I need?

Added 2 more pictures. I have no other pictures but the rest seems standard to me. On the side of the door there is a metal plate with the pieces that go in and out the frame (sorry about the lack of right terms, even in my language I don't know how to name these). On the exterior the knob and system are different: the knob does not have a nail and there is a key lock instead of this round metal piece.

Edit 2
I would like to remove the "golden" plate and the knob but keep the same lock. Question is can I remove this round piece and how without disassembling the whole system inside the door.

Edit 3
Set the pictures to original size (bigger) and added another picture.

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  • 1
    Please give us photos of the rest of the system. I doubt that you need to remove that pin.
    – isherwood
    Commented Jan 6, 2023 at 14:10
  • 3
    That might be a hex grub screw, but there's not enough detail in the picture.
    – Tetsujin
    Commented Jan 6, 2023 at 14:23
  • @Tetsujin there was another picture that was edited out (?) because the nail/pin is not the same size on both sides but it is definitely not a screw. This nail is visible on 2 sides (180°) that is why I thought it would come out when pushed. Commented Jan 6, 2023 at 14:26
  • 1
    I also suspect two grub screws. Do you have a set of hex keys you can try? Commented Jan 6, 2023 at 14:45
  • 1
    @isherwood I think you're right. After a ton of googling it turns out this seems to be what is called an "euro(pean) lock cylinder". Apparently best thing to do is to remove it completely to change the plate and the knob. Had I posted a picture of the profile of the door (side) you would have found it, sorry. Commented Jan 6, 2023 at 22:13

2 Answers 2


Thanks to isherwood's insightful comment and after a ton of other research (plus posting my question in a French locksmith forum :) it turns out this is what is called an Euro(pean) Lock Cylinder with a "button" on one side (as opposed to key holes on both sides). So apparently the best procedure is to completely remove it, which does not require disassembling the whole system, as shown in this video:



That appears to be a set screw holding the knob in place. Others have suggested it is a hex screw; I think it's more likely to be a flathead screw whose head is almost completely stripped. You could try removing it with the usual tools (e.g. a screw extractor bit), but it will be hard to do that without damaging the lock.

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