Doing a project with locks, and need some help.

[ridinplugspinnaz]

If your goal was to create a lock that would trap keys other than your own, I could see you devising a system like this as a variant on the trap pin systems that exist in some higher security locks. Just off the top of my head, you could modify the plug and key of a cylinder such that you have an additional tumbler or two a few degrees off-center from the main bible of the lock on either side. It would require some custom fabrication work, and a slightly-modified key (only for the legitimate user), but basically the goal would be to create an interstitial pin of sorts for these trap columns, in other words a pin of substantially smaller diameter that would contact the key on a peak between the standard pin positions for a KW1 key.

The idea here is that for a key cut to the correct peak height in between the standard KW1 cuts, this custom pin would contact the peak, the top of the key pin would meet the shear line, and the cylinder would continue to turn. By contrast, a standard key that was code-cut or duplicated would have a lower-height peak, dropping the driver into the cylinder once the key is turned a few degrees and trapping the key in the turned position.

Granted, this would require a fair amount of custom work on the cylinder. You'd need to be able to implement secondary bibles on the cylinder for these pins, you'd need to drill extra holes in the plug and the cylinder housing, you'd need smaller pins themselves, and you'd need to cut your working key carefully. For some bittings, that could possibly violate MACS on your run-of-the-mill Kwikset lock.

Don't hold me accountable if this post doesn't make any sense, it's late and I'm tired. Goes to show you what crazy ideas pop up in your head when you're burning the midnight oil... but I think if you had access to good machining equipment and you knew your way around a shop, you could make something like this work.

[femurat]

I recently bought a dimple lock to play with, but it was too hard for me (ISEO R6: 6 pins with 4 spools and a strange keyway). I decided to disassemble it to put away a few pins, so I removed the C clip, entered the key and turned it a little to extract the plug. Suddenly the plug was locked and the key trapped!
I did the same with the other side plug and I hadn't any problem.
Looking at the "free" plug I discovered that there was an extra hole on the side of the plug that trapped a pin when I turned the key.
Now I have to drill the 2nd pin side on the cylinder to extract the trapped pin and key

I can take a picture of the lock this evening so you can better understand what I mean.
You may think about something similar for your project.

Cheers

[ridinplugspinnaz]

I recently bought a dimple lock to play with, but it was too hard for me (ISEO R6: 6 pins with 4 spools and a strange keyway). I decided to disassemble it to put away a few pins, so I removed the C clip, entered the key and turned it a little to extract the plug. Suddenly the plug was locked and the key trapped!
I did the same with the other side plug and I hadn't any problem.
Looking at the "free" plug I discovered that there was an extra hole on the side of the plug that trapped a pin when I turned the key.
Now I have to drill the 2nd pin side on the cylinder to extract the trapped pin and key

I can take a picture of the lock this evening so you can better understand what I mean.
You may think about something similar for your project.

Cheers

Actually, now that you mention it, drilling shallow holes into the bottom of the lock sleeve would be a 100x simpler way to catch the key pins once the lock has been turned 180 degrees. That solution will trap all keys though, as opposed to only "unauthorized" ones.

[raimundo]

if your key has some deep cuts, you may be able to do this,

bottom pins have a rounded or conical bottom to interact with the cam surfaces on the key,

when top pins are used as bottom pins, they do not have this necessary configuration, and if you have such pins in the bottom, they will tend to stick on any defect along that cam surface, when this starts happening, trying to forcefully jerk the key out will tend only to deepen the defect in the surface.

however if you put all top pins, (find ones that have as little bevel/chamfer on their edges) in the lock it may also make it just as hard to insert the key, you can finness this by using a file to put one slanted edge on the top pins and insert them in the direction so that this edge meets the cam surface of the key coming in, once in, the key will be difficult to withdraw, and the more force applied, the more the pins will impression a defect on the cam slopes for with drawing the key

[sams choice]

I would like it to catch ALL keys. ANY key inserted will work. I figured a way so that keys with a pin set to 1 will work but that is all i figured out.

[Engineer]

I've posted a little about "Judas mechanisms" here:

http://www.lockpicking101.com/viewtopic.php?f=25&t=42803

The problem is usually how to trap a key and how to remove it again without ruining the lock. Knowthebird provided a solution for how to free the key afterwards, but as for trapping it?

Well, the best method might be a cam mounted so it passes through a slot where the pin nearest the outside of the keyway would normally be and on a ratchet. When the lock is turned, if it is not the correct key, a cam rotates across the last cut on the key, until the key is wedged tight in the keyway. The cam is on a ratchet, so the key cannot be removed. An alternate locking mechanism then has to be used, to reload the spring-loaded cam and you can withdraw the tell-tale key then.

[sams choice]

I've posted a little about "Judas mechanisms" here:

http://www.lockpicking101.com/viewtopic.php?f=25&t=42803

The problem is usually how to trap a key and how to remove it again without ruining the lock. Knowthebird provided a solution for how to free the key afterwards, but as for trapping it?

Well, the best method might be a cam mounted so it passes through a slot where the pin nearest the outside of the keyway would normally be and on a ratchet. When the lock is turned, if it is not the correct key, a cam rotates across the last cut on the key, until the key is wedged tight in the keyway. The cam is on a ratchet, so the key cannot be removed. An alternate locking mechanism then has to be used, to reload the spring-loaded cam and you can withdraw the tell-tale key then.

I like the way you think.The lock does not have to work again. It could break and lock the key in there. They key does not have to be removed or ever able to be removed. I am thinking of a mouse trap like design that will lock down on the key. I like the ratchet idea...

[unjust]

so what does that *do* then? why? theory is well and good, but if youjust want to catch a key, replace teh pins with a ratchet mechanism that'll bind against the peaks.

[Engineer]

The idea is that you issue keys with a number on the bit you stick in the lock. Each key will allow access to only certain areas - A bit like a master-keyed system. Think highly-secured areas.

If someone tries to enter an area they are not authorised to enter, their numbered key is trapped and they have to explain why their key is in that lock. Even if the head is broken off, the number on the retained end of the key identifies the owner of the key. If the key is stolen, then the locks are re-pinned and if anyone ever tries to re-use the stolen key, not only are they foiled, but the old key is retained, so it cannot ever be used to attempt entry again.

so what does that *do* then? why? theory is well and good, but if youjust want to catch a key, replace teh pins with a ratchet mechanism that'll bind against the peaks.

[sams choice]

Solved it!

Now the problem was making the key stay into the lock. The way i did this was by shaving the last two pins down to the ward in the cylinder and exposing the key, one may hook up a mouse trap to spring down and hit the key. When this happens, it warps the key and caused it not to be able to be removed from the lock. I was not looking for a lock that would make my key work. I wanted no one's key to work...

Pics!!!

[ToolyMcgee]

Seriously? The key doesn't spring the trap, and there is no room for it to snap on a key inside a door. I don't see how you solved anything. I see you cut up a lock so you could snap a mousetrap on the inserted key, but that isn't going to trap a steel key and I bet 1 quick tug will get that brass key out of the lock.

I was not looking for a lock that would make my key work. I wanted no one's key to work...

Looks like the operating key will still turn the plug to me. The mousetrap isn't stopping that either.

What is the purpose in making a key catching lock that traps any key inserted? Who is this going to benefit? What is the point!?

-'Mcgee

[femurat]

This is the plug I was talking about: you can see the extra hole on the right side. My key got trapped when I tried to extract it cause I removed the C clip and turned the plug 45 degree CCW. This hole is not aligned with others: it's exactly halfway between the first and the second one. If the plug is in its proper position it can turn easily, but if you remove the C clip and pull the key a little you're done.
I'm not saying this is the solution to your problem, but this could be an idea to develop. Like the harpoon concept...

Another idea for your unusual project
You can make a better trap by connecting the plug with the ground and a special insulated pin to the positive cable of a car battery: this could melt and trap every key inserted. The bad thing is that couldn't be easy to identify the unlucky man!!!
I'm just joking and if you are mad enough to try this ask a professional electrician advice to avoid electric shock risk.

By the way, I'm curious too about the purpose of this project. Do you mind to tell us something more about it?

Good luck!

[maintenanceguy]

There's an easier way. Remove the plug and drill two shallow holes in the plug, on on either side of one of the regular pin holes.

When a key turns the lock, the top pins drop into the shallow holes you've drilled pinning the plug so it can't turn at all. Since the plug can't turn, the pins can't be lifted and the key is retained by the pins that are stuck down in each key cut.

I've done this as a trap before. The details are here viewtopic.php?f=3&t=43270&p=326085#p326085 about 2/3 of the way down the page.

Down side, the lock is ruined but replacement cylinders are cheap.

[Manong]

You could put #0 bottom pins in the first three chambers with a stack of master pins above,
sized for increments of 1 cut. This would ensure that any key could begin to turn the plug.
Cap the 4th and 5th holes of the plug, with no bottom pins, but long drivers in the bible.
Drill new chambers into the plug say at 45 degree angle bot on the right and left side to catch
the long drivers when the plug is turned.
When any key is put in, it will turn the plug to the 45 (or 90) degree angle then stop, when the long drivers drop in. The pin stacks of the first three chambers will be trapped, and the key will not come out.
You would need to think about some other way of accessing what is behind the door, or having
no bolt or latch operated by the lock, making sure that no one could be trapped physically etc

[Engineer]

Whoa! There seems to be some confusion going on here - I'm really sorry if I caused any of this.

The idea is NOT to trap EVERY key inserted, but what I was talking about anyway, was a lock that would trap only wrong keys inserted, or would semi-permanently lock up if someone tried picking it.