cam,actuator, keys on both sides,(Why) will/won't this work?

[ARF-GEF]

Ok so this might be a dumb newbie question.
If you put your key in a lock and turn it halfway then that’s the ultimate security measure isn’t it?
I mean supposing there’s no emergency function or something similar then the lock can’t even be opened with its own key from the other side. So impressioning is already out. If you can’t actuate the cam (And that’s what the case here is, isn’t it?) it doesn’t matter if you can pick or bump the lock. You can’t push the key out from the other side since it’s halfway turned and the key retaining mechanism/pins won’t let the key out.
I think this would even make destructive entry harder since even if you make a new shearline with drilling you can’t turn the cam because of the other key on the other end.(?)
This seems all too easy. Where am I wrong? Could someone explain this to me?
Thanks for the help/explanations in advance!

[femurat]

Leaving the key on the inside of the door is a very bad habit, since it's possible to turn it from the outside (with a thin wire if euro profile lock or with other tools if lever locks "doppia mappa").

Cheers

[LockDocWa]

Every lock is a different animal.
Can you be more specific as to what lock you had
in mind when you had this Epiphany?

[ARF-GEF]

Thanks femurat, I didn't know that!
I thought about a simple pin-tumbler euro profile lock ( iwas playing with a gege cylinder when this question came into my mind to be very specific.).

So leaving and turning the right key is a bad idea. What about simply putting in a fitting key which is cut differently. You still can't insert the key from the other side, can you?

(Epiphany- )

[femurat]

This may work, if the cylinder hasn't the "security" feature.

Cheers

[ARF-GEF]

What do you mean by "security" feature?

[femurat]

An euro cylinder with the "security feature" is one that can be opened from the outside even if there's a key inside. This is more and more common here as let's you enter with your key even if a family member is sick in bed and left the key in the door.

Cheers

[ARF-GEF]

Oh, I know what you mean now. I just didn't know this expression for this feature.
Funny how many names it has. Some call it security others call it emergency function evva calls it KZS some others simply both side operable.

[femurat]

Heck I may be wrong, emergency sounds better...

[Solomon]

Leaving the key on the inside of the door is a very bad habit, since it's possible to turn it from the outside (with a thin wire if euro profile lock or with other tools if lever locks "doppia mappa").

Cheers

You're thinking of thumbturns mate, that only works because of a specific type of cam design some of them use. If there's a key on the inside there is no way to simply turn it. Mortice locks yes, euros no.

ARF-GEF, if you have a key on the inside it can still be opened by picking. Just pick the cylinder as normal, then insert a wire or pick into the back of the cylinder and push on it a little while turning the plug until it pops into the cam notch. From there you just hold pressure on the cam while turning until you feel the bolt throw. It can be annoying at times but it's simple enough. You have to do the same with thumbturns as the cam is always engaged from the inside.

As for bumping, you're right, a key can't go all the way into the lock... but if you modified the tip by simply filing it until it went in all the way, it'd work no problem. You'd need to remove it and grab the cam same as before of course.

[ARF-GEF]

Thanks for the info Solomon! I didn't knew you can pick them that way.

What I don't quite get is why can you make the lock turn by pushing the back of the cylinder? Although I have an idea it would be better if someone more knowledgeable could tell it for sure.
The cylinder I played with didn't even let the key enter all the way. So if you can't push the back of the cylinder with the key why can you with a pick?
If the key is entered from the other side and thus the cam is in actuated by the other side you have to move the key on the other side as well, won't you? But is that even possible or where am I wrong?

I'm sorry, I still can't understand the why behind this whole mechanism.

femurat: Maybe it's also called as security function. It seems to me that lots of companies have a different name for it. Plus it probably varies from language to language.

[mhole]

Pushing a key into one side of a euro cylinder pushes a small mechanism inside the cam, which connects the cam to the side of the cylinder you inserted the key into. Once the key is in place, the mechanism cannot be pushed across the other way without removing the key. This is why you cannot use a normal key to operate the lock.

*However* you can push something far enough down the other side to hit the cam, and if you maintain pressure against this it will turn the cam, and the other side of the cylinder with the key in it. So you're not actually using the normal mechanism to connect to the cam, you're using a rather more tenuous connection, by hooking into a groove or depression in the cam.

You mentioned inserting a non-working key to block access from outside, but this won't work, as inserting a key outside will simply push the incorrect key out.

Leaving a working key on the inside of a euro to prevent access does work, and is no less secure then leaving nothing in it, as the lock must still be bypassed or picked to engage the cam and open the lock. You do however, run the real risk of locking yourself out by forgetting to remove the key. If you're in London, feel free to do this, it's all extra business

[ARF-GEF]

Well thank you for the explanation this whole ting got a lot more clear!
Time to take apart a cylinder and find all the details out.

[femurat]

Thanks Solomon and mhole for the clarifications. I was a bit confused that day and used some wrong terms.

Cheers