Remove Corbin core, SFIC padlock

[catsoup]

I have a Brass Padlock with a Corbin Russwin SFIC. I've had this lock for a while, got it in an exchange and have a key for it/can pick it no problem. I am under the impression that these cores have a four pin control key? I dont have that key, and would like to remove the core. Any suggestions? is there a technique to picking for the control - does it rotate the same direction? From my research it looks like it is pins 2345?
I like this lock, it is nice and heavy, so I would prefer not to damage it in anyway.
There don't appear to be any visible screws or anything like the American series when the lock is open.

Here is the lock I'm working with

[cledry]

It is a LFIC surely?

The only trick I know is to put pressure on the retainer lug after picking the front and back pins to the shear line. I would just drill the control shear line and pop a new plug in it though.

[cledry]

Forgot, yes it turns the same way to remove the core.

[catsoup]

Yes LFIC, not sure what I was thinking there.

As far as the trick you are talking about goes, I set the first and last pin, and then put pressure how? what will that do for me?

[Evan]

I have a Brass Padlock with a Corbin Russwin SFIC. I've had this lock for a while, got it in an exchange and have a key for it/can pick it no problem. I am under the impression that these cores have a four pin control key? I dont have that key, and would like to remove the core. Any suggestions? is there a technique to picking for the control - does it rotate the same direction? From my research it looks like it is pins 2345?

@catsoup:

That padlock is a Corbin-Russwin LFIC... It appears to be one of the Z-class keyways (59 family, 60, 70) based on the bow shape of the aftermarket key you are using...

CR LFIC's use a control key the same length as the number of pins in the core, i.e. 6 or 7... The control bitting is usually 2 of the chambers in the range you have discovered, chambers 2, 3, 4 and 5... So the control key uses the TMK bitting (or operating key bitting in single keyed cores) in the positions other than the two it is different in order to establish the control function...

Which of those two chambers are being used for the control function is is up to the person who keyed it... You do know that the control key is NOT the same as the TMK or operating key in a single keyed core in those two chambers where it works its function... Common pairs used for the function are chambers 2 & 3, 3 & 4 and 4 & 5...

So it is a puzzle that you can solve since you have an operating key and if you also have the ability to cut your own keys to factory specs, similar to the Blaze technique to reverse engineer a master key, you can explore the other possible depths in those chamber pairs and only need to use 4 (Pre-70) or 5 (System 70) blanks per pair explored...

Ex:

Operating key bitting: 123456

Exploratory key bittings: 123(X)(Y)6

where the X is not equal to 4 and would have to be
another valid depth other than 4 which are:
(Pre-System 70 = 2, 6, 8, 0) (System 70 = 1, 2, 3, 5, 6)

where the Y is not equal to 5 and would have to be
another valid depth other than 5 which are:
(Pre-System 70 = 1, 3, 7, 9) (System 70 = 1, 2, 3, 4, 6)

Pick one depth for X and then start with the shallowest possible Y working your way through all the possible Y values... Then pick another X and repeat the Y progression...

You can see the idea and how to figure out which bittings would need to be tested in the other possible control positions if you don't figure them out with the first exploration... This would be a simple exercise which could be done rather quickly if you have a code machine available but would take much longer if you had to manually file the keys with each attempt...

~~ Evan

[cledry]

I have seen half depths used in the control chambers, but not common. I have also seen more than two chambers used in non-factory systems.

To put pressure on the side bar you can drill a small hole in the side of the lock and plug it later. Still easier to drill and replace, unless you just want a challenge.

[Evan]

I have seen half depths used in the control chambers, but not common. I have also seen more than two chambers used in non-factory systems.

@cledry:

As in "half depths" of System 70 (.028) ?
Which would be Pre-System 70 keying (.014) ?

Were those systems you saw using more than two of the control chambers part of a master key system ? The problem there is now you have removed two bittings per control chamber used when you use more than two of them from the system progression as you would not want to have either master keys nor change keys which have a control bitting on them as they could jam the core...

~~ Evan

[catsoup]

So if it is part of a master key system, the options are limited? Or does that make it more complicated.
I don't know if this would be, Im just trying to figure out where to start to determine which pins are for the control.

Also thanks for the help thus far, interesting stuff.

[Evan]

@catsoup:

If the core was part of a master key system it just means that there are more bitting depths which will open the lock in each of the positions... It also means that the core must obey some keying rules and it will be easier to discover the control bitting vs. the core being single keyed...

~~ Evan

[cledry]

I have seen half depths used in the control chambers, but not common. I have also seen more than two chambers used in non-factory systems.

@cledry:

As in "half depths" of System 70 (.028) ?
Which would be Pre-System 70 keying (.014) ?

Were those systems you saw using more than two of the control chambers part of a master key system ? The problem there is now you have removed two bittings per control chamber used when you use more than two of them from the system progression as you would not want to have either master keys nor change keys which have a control bitting on them as they could jam the core...

~~ Evan

System 70 yes.

Yes, they were part of a MK system, albeit a really small one. One I recall was about 15 locks.

[catsoup]

Okay, so I have now removed the core, and removed the pins from this lock, and it appears to be part of a master key system. I contacted the guy I got the original from to see if he had anymore from where this one came from. He sent me another that has the same user-key as the original, but the control key I made doesnt remove its core! So here is my question. What are the odds of there being two control keys within a single master-key system? and is it possible that I got the control key wrong?

Here are pins 2345, which are the control. Pins 1 and 6 are the same on both locks/keys, and don't touch the control cylinder.


It appears as though the only option for the control is the shear below the uppermost pin. This is because when the lock is loaded with the pins and no key, they all fall below the control shear line, as illustrated in this photo.

When I load up the cylinder [without the top pins, since they at least have to be on the spring side] and put a blank key in, pushing each stack to the maximum height possible, I get this. What you are seeing is all of the second-from-the-top pins passing the shear line.

My reasoning here is that if the control was anything other than the shear line between the uppermost and second pins, I would be able to achieve a shear between another pair somewhere between no key and an uncut key, though this experiment shows that is not the case.



So am I missing something here? Is there another explanation other than two control keys?

[cledry]

Using your last photo as an example. When all these pins are at the shear line of the control lug and 1 & 6 are at the shear line of the lock cylinder then the key will act as a control key.

Do you know whether the key you have is the change key or the MK? The control key will have 1 & 6 in common with the MK always. Usually two of the four in the control lug will match the MK and two pins will never be used in the system for the MK or the change key. This is common practice, but I have seen only one pin differ which is not good practice.

[cledry]

BTW pin chamber 3 has an extra pin for some reason.

[catsoup]

I understand this. I created a key that functions as a control for this lock, I'm just wondering if my method is flawed in determining if there is more than one possibility.

I now have a user key and the control. Im trying to find out if there is any other possible control key, considering pins 2345.

[GWiens2001]

If the stack for bitting #3 has an extra master wafer, perhaps you could have the extra control key at that point. File/cut all other bittings exactly the same as your first control key. Then cut/file the third bitting to the next lower master pin split, which should be the next bitting at the control shear line. Remember, this will probably not be as deep a cut as your origional control key. To be more specific, and save you time, it will be a shallower cut by the height of the second pin from the top on that stack.

This is, of course, assuming that your first control key was cut to just below the control shear line on each pin stack. If this works (which it should), you may have found the second (for the first lock), proper control key that will work on both locks. If the locksmith who assembled the first lock accidentally lost his space and dropped in an extra pin in the third position, it would not change the operating or origonal control key, but would create an additional control (and possible additional operating) key.

Good luck,

Gordon