5 Pin tumblers - will turn, wont open

[xile]

While i was picking a 5 pin tumbler lock i raked it, the wrench turned, it turned nearly 45 degrees, then it just stopped, no amount of raking could get it to turn further, so i just turned it back and tried again. It usually opens when you turn it 45 degrees. Why wont it open?

Ive also had this problem with a wafer lock, it turns nearly 180 degrees but stops just before it would normally open.

Any ideas?

[TheCotMan]

While i was picking a 5 pin tumbler lock i raked it, the wrench turned, it turned nearly 45 degrees, then it just stopped, no amount of raking could get it to turn further, so i just turned it back and tried again. It usually opens when you turn it 45 degrees. Why wont it open?

Ive also had this problem with a wafer lock, it turns nearly 180 degrees but stops just before it would normally open.

Any ideas?

Here are two "obvious" answer you may not have considered:
Is the lock broken?
Did you try turning it "the other way" instead?

There is an old joke about lock pickers that who fail to check to see if a lock is actually locked before picking, and end up locking instead of unlocking the lock.

For people who pick, and make the mistake of picking with a rotation in the wrong direction, there is another tool called a "plug spinner" that allows you to take a lock that has been picked and rotated the wrong direction, and rotate the plug in the other direction. It works by putting tension on a "wound spring" that has a flat "tension wrench" wafer of metal placed in the keyway. When the spring is unwound (quickly) the plug spins in the opposite direction so quickly, that it prevents the pins from being reset, and leaves the plug rotated in the opposite direction.

Google Images: "plug spinner"

There are other reasons (lock features and security enhancements) for a lock to fail to unlock when the plug is spun in the cylinder, but I should give other people a chance to answer. (Evil Grin)

[xile]

cheers but no, when i went the other way it did pretty much the same thing except it didnt turn as far. the lock is not broken as i can open it with the key, and therefore i know im turning it the right way, and i also know its locked. Im just raking it, so it might be a security enhancement, that was my first thought. Any other suggestions?

[TheCotMan]

Any other suggestions?

Sure. There are several technologies used by makers of locks to try to make picking/raking less conveinient.
One example is a "back plate" after the last pin that either must be pressed (usually with the tip of the key when it is inserted in the keyway) in order to actually open the shackle/latch/unlock the lock, OR a backplate that when pushed while tension is placed on the plug (with the tension wrench) causes "set pins" to not let the rotation of the plug in the cylinder cause the lock to become "unlocked" until the plug is reset to its neutral position and tried again.

Another security measure that is probably not in place, since you mention you were able to rotate the plug 45 degrees, is a set of extra pins (magine a master pin inserted between the top and bottom pin) that provides a false positive on each pin's sheer-line, and lead to "jambing" this extra pin into a guard, part way through rotation. (I've read of techniques to defeat these are similar to those for mushroom pins and pins with serated edges.)

Another possible item is a non-anti-pick feature that is used on some construction sites, where there is a construction master that must work until some date, when the construction master must be disabled. Special locks are equipped with special pins and one or more extra "bearings" , "blanks" or "inserts"are located in part of the pin assembly, that roll out of place when a special key is inserted into the lock, and rotated in a specific direction, changing the pintout/keycode, disabling the construction master, enabling a new master.

These allow a one-time build of locks that allows distrobution of keys that don't work, but soon will, and a collection of construction keys and construction master that will work, but soon stop. The only change to enable one, and disable the other is a special key to set the pins to a height to "dump" the bearing/inserts, once inserted and rotated. Such keys do not unlock locks when inserted and rotated.
Picking such a lock (if it had multiple bearings/inserts) may give multiple false-positives until all bearings/inserts are removed.

And yes, there are even more anti-picking technologies included in higher security locks.

I won't post anything more in this thread until someone other than you or me posts an answer. Really. I mean it this time. (heh)

[Deviant Ollam]

do you have a make/model on the lock? can you post any photos of the lock and/or its key? you say that the lock operates without any trouble if the key is used?

[Cowthief]

Odd lock cylinders.

Hello.

In the Best interchangeable core locks, there can be a split core.
This is a 2 piece core with an inside core and an outside core.
With the correct key, the outside core turns, the tailpiece is connected to this and works the toggle.
If you pick the lock, or an incorrect key is inserted, only the inside cylinder will turn, at this is not connected to the tailpiece, the toggle is not moved.

This might be this construction lock TheCotMan pointed out, however I was not around for this places construction.

I would like to know more about this lock as well as the construction master type of lock.

[TheCotMan]

This might be this construction lock TheCotMan pointed out, however I was not around for this places construction.

Yep, this is what I was describing above, but with those locks, the user usually cannot rotate the plug 45 degrees. Usually, the plug only rotates part of the distance before the middle pins engage with a guard, and it is possible to have guards aligned for each pin at different points of rotation, but I've not seen these.

Google for "sidebar" with high security locks too. Using several of the above keywords, you should be able to now google for possible technologies responsible for causing what seems a successful raking/picking into a non-successful attempt.

Sample pages found:
http://en.wikipedia.org/wiki/Lock_picking
http://www.crypto.com/papers/notes/picking/

Several others came up too.

Find a page discussing several "high Security locks" with lockpicking, and you may find long lists of lock-types that act like the lock you describe.