idea from old worn out cylinder lock

[inverseentropy]

I bought a box of old cylinder locks from ebay. There is one of them that I cannot pick. When I lift the first pin, the lock rotates 5 degrees. When I don't lift the first pin, none of the other pins bind. I shimmed the thing and took it apart. The back five pins were really low - so low that they just barely passed above the shearline. The top part of the cylinder is a bit worn down so that it is possible to rotate the plug a bit (but not far) when these pin stacks are not raised.

I think that this concept could be exploited to create a lock that is difficult to pick. The first pin is normal, the other pins are as shown in the picture below. The concept is a bit similar to spool pins I suppose, except that spool pins are easy for me whereas this lock seems to be beyond my abilities. There is no counter-rotation as there is with spool pins. The diagram below represents the cross section of this old lock of mine, except that my lock rotates much farther than the one I have illustrated below.

[FarmerFreak]

It looks simple enough to make and try out. May I suggest using a second top pin just so the spring doesn't accidentally get bent out of shape.

What I think you will find is that over-setting the pins will be an effective method of picking this lock (think rake picks). The reason is because if any pin is over set by no more than say 2 depths, it will still turn slightly. After that, releasing the tension should automatically set those to the correct depths.

It will likely prove very difficult to single pin pick a lock setup this way.

[inverseentropy]

That's an interesting point about over setting. I suck at raking so I'll either have to get better at that or have a few rake experts try it out. Soon I should have access to a drill press so I can make a few of these. The old lock I have now can be opened by just lifting all the pins up, but that is because all positions are pinned to the same depth. I think that this whole box of cylinders came from a locksmith who was practicing bumping technique. They all have indentations on the lock face and are all pinned really high (presumably to make them more of a challenge to bump).

And speaking of bumping... I suppose there is a good chance that this thing would be easy to bump since the "effective" shearline is quite wide.

[Rickthepick]

This is why a lot of cheaper locks such as tri-circle are a to pick