Countersunk lockcylinder!

[Elzett!!]

Hello!

I would like to know what is the relevant difference between a drill countersunk lock cylinder compared to a non-drill countersunk lock cylinder? Have some padlock with countersunk cylinders at home. At the moment two Tri-cycle padlock and one Diamond padlock.

Then, I also wonder why the lock with countersunk pinchamber are harder to lock pick?

[raimundo]

I was wondering what you meant by counter sunk lock cylinder, picturing a whole cylinder looking like a screw that was sunk flush with the plane of the door,

But by the last line I think that you were specific to locks with a chamfer on the plug drillings,

if the top pins also are chamfered, this can make getting the pins to sit on the little step that is created by the tension offsetting the plug from the cylinder, but this is not actually unpickable, as the two chamfers interacting can also cam the pin back to the shear line when the last set pin happens,

Hope this makes some sense and helps.

[Elzett!!]

Thanks for the reply.

[MacGyver101]

Just to double-check: are you talking about counter-milled pin chambers, like this...



...or do you mean that the face of the plug is recessed, like this...



raimundo was talking about locks that are manufactured like in the first photo (where the counter-milling is inside the lock). If you're asking about something like the second photo, then the plug position doesn't have any real effect on the ease/difficulty of picking.

[Elzett!!]

I was curious about both, and now i got complete answere to my two questions.

[Raymond]

In general, the lock that has been "counter-sunk" on each pin chamber will be easier to open. This greatly increases the gap between the plug and cylinder and accuracy is gone.

This is similar to the great no-no for locksmiths. I still see plugs that have been filed flat across the pins. The lock always works better if the keys are sloppy or mis-cut. This is a quick fix and a very bad habit to start.

This also leads to a common problem for filed or chamfered plug holes. If the lock is masterkeyed, a thin master wafer can move halfway into the shearline gap and become wedged. A lock this badly boogered should be replaced.

[Evan]

This also leads to a common problem for filed or chamfered plug holes. If the lock is masterkeyed, a thin master wafer can move halfway into the shearline gap and become wedged. A lock this badly boogered should be replaced.

@Raymond:

This is correct, a cylinder plug which has been filed flat at the top across all of the pin stacks (there is NO legitimate reason to do that ever) or that has one or more chamfered pin stack holes should be replaced so that you can use the standard specifications for that type of lock to master key them...

However you can accommodate chamfered pin stacks in the plug by increasing the number of bitting steps between the keys you create in the master key system (i.e. instead of single-step progression use two-step progression OR instead of two-step progression use three-step progression) which would reduce the size of the system greatly to accommodate someone's past butchery of the lock cylinder and your cheapness and current scrooge-ry and unwillingness to replace the butchered locks...

The common reason why one or more pin stacks will be chamfered is because someone is creating a "shoebox" master key system which doesn't obey the keying system rules for that lock manufacturer because of the random keys being cobbled together into a system... (example: a Schlage lock that has a master key bitting of 2 in the same chamber where the change key bitting is a 3... Since there is no #1 Schlage master pin because it is too thin for the locks tolerances, the lock is keyed to the shallower bitting with a #2 bottom pin, the plug is then chamfered until the key with the #3 bitting will work by allowing the top pin to ride up the chamfer and allow the plug to rotate when the deeper cut key is used...)

~~ Evan

[tryxiegirl]

Very informative post. Thanks!