Chubb 3G110

A big thank you goes out to Simon Owen for providing this informative guide on understanding the Chubb 3G110. I have known Simon a long time and he understands this lock as well as anyone I know. Hopefully this information will help those who are experiencing problems in opening the lock.

This guide has been written to enable users of the Safeventures 110 pin and cam system to better understand a technique for opening these locks.

The technique relies on you identifying the difference between pattern 2 and pattern 3 detainers, once identified it is much easier to find a true gate.

Often too much rotational force results in ‘false binds’ which cause false pin moves which will result in the lock not opening. Fractional movement of the cam is all that is required
If you follow the process of identifying the lever pattern first and sticking rigidly to this system Chubb 110 lock opening should become much easier.

A detailed knowledge of the working parts of a lock enables you to understand better what is going on during the decoding process

Fig 1: Chubb 110 internal named parts

The bolt thrower rotates and lifts the vertical linkage (secondary gated lever). This allows a pressed stump to clear the gate of the bolt.
Only when the correct key is inserted will the detainers line up allowing the bolt stump which is part of the detent arm to move which will allow this lifting process. A full description of history and operation of the lock can be found in High Security mechanical locks by Graham Pulford.

Fig 2: Key reference

During the decode of most standard 5 lever mortice locks positions 1 and 3 (1 being closest to the bolt) are the same for reasons of key symmetry. This is often referred to ‘ABA pattern’ which assists when decoding.

Standard 5 lever mortices normally have seven cuts, the chubb 110 has nine.

Although the key is symmetrical we have no ABA pattern in the decode so the detainers are referred to as A to E.

Fig 3: Cut heights

1: 14.0mm
2: 13.4mm
3: 12.5mm
4: 11.7mm
5: 11.0mm
6: 10.3mm
7: 9.5mm
8: 8.7mm
9: 8.0mm

Series contains 9 differs, 1 being highest cut 9 being lowest. The scale is available from Souber tools. Be aware of the levers not directly relating to the factory specified height. This is a slight fault in the manufacturing process which does not effect the correct key (as the detainers are vertically milled whilst seated on the key) but it can give false decode readings ending in an unsuccessful entry.

Fig 4: Chubb 110 pin and cam

This is a modified 110 pin and cam decoder. In operation it is the same tool however the tip has been machined to a theoretical 10 cut to allow for 9 pin tests.

Fig 5: Pin box

Pin box containing 5 pins per differ, again modified for 9 pin height.

The  system.

The decode system works on the principle of identifying the pattern 2 and pattern 3 detainers. Called as such due to having 2 or 3 shallow false gates machined into the fence of the detainer. These false gates can be detected and will interact with each pin during the decode process.

Determining the difference between P2 P3 is described fully and is fairly straight forward. It is advised to project this noting the differences whilst decoding and practice identifying P2 and P3 detainers.

How the system works

Close inspection of the pictures on the previous pages show the interaction of the bolt stump and the lever. Once you can distinguish which pattern of lever you are working it becomes simple to identify when the system changes.
Every pin height interacts in a different way on the P2 and P3 detainers and when you get a change it is very obvious.
When the reading changes it is safe to say you are in the true gate.

In the above case the detainer will have fractional movement followed by bind upon lift. The reverse, a bind followed by free moving cam can fool the user into thinking they are in a true gate.

Locate your most binding detainer and only drop a pin if it binds at TDC (top dead center). If it moves even fractionally, do not drop. It will either be correct or it will bind the closer you get to decoding the lock.

User should construct a chart showing interactions at all heights between the detainer and bolt stump. Incorporate it into the pin box helps you to work through the system. An example chart is contained in the document.

The biggest common mistake is to drop a number 1 pin when it is in fact supporting a number 1differ detainer.
This happens because of the production of the detainers sometimes causes a slight increase in the height – a 1-1/4 height. A cut key to 1 height will open this fine, a fractional lift with a number 1 pin will cause the lever to bind, giving a false reading. You will continue to test through the pins without any success.

The rear cam indicator should be moved no more than about 3mm in one direction only (user choice).
If the cam moves (even minutely) leave that position alone!
Only move down binding levers. If no lever binds perform a 9’s test

Do not use too much force, this will possibly damage the cam which will provide false readings and you will damage your pins.

A small line drawn onto the rear of the body will ensure that the cam is lined up correctly prior to insertion. This must be done to avoid false readings.

The tool should be regularly serviced. Strip the tool completely clean and polish all internal components. This keeps the operation smooth as it is important in distinguishing the difference in the readings.

Round off the pins and ensure that they are not bent, they will stick in the tip pin chambers and again give false readings. A small quantity of grease applied to the pins prevents any loss and assists in smooth operation

The ‘Nines test’

The “nines test’ is merely the consecutive removal of pins.
You have tested all positions with no bind.
Remove position A detainer and re-test all other detainers B through to E. If when one pin is removed another position then binds it is a very good indication that the removed pin is a 9. It cannot be an anti-pick notch as they are not that high up on the fence of the lever.

If a single nines test fails to identify a binding lever it can be assumed that more than one nine is present. Chubb do not use identical levers next to each other therefore pin removal sequence is obvious. Positions B and D are tested first followed by positions A, C and E.
If a nines test fails to work the system has not been correctly followed and it is suspected that a pin has been dropped wrongly. The user must re-start the process.

Old style detainers

This system was developed to assist in opening the new style detainers because although the antipick notches are very shallow they are designed specifically to thwart the use of decoding tools.
The old style detainers were either totally blank or had antipick notches 1 height above and below the true gate.
The notches are approximately 1/3rd of the depth of the true gate and exactly the thickness of the bolt stump

1    Notch above gate and in ‘toe’
2    Notch above gate and in ‘toe’
3    Notch above and below gate
4    Notch above and below gate
5    Notch above and below gate
6    Notch above and below gate
7    Notch above and below gate
8    Notch below gate, slight notch above gate
9    Notch below gate


Lock dimensions

(a). Manufacturer;                   CHUBB                chubb
(b). Mechanics;                       5 DETAINER         
(c). Colour;                              GREY   
(d). Tone;                                MATT/METALLIC
(e). Keyway height;                 14.0MM
(f). Pinsize;                              5G
(g). Anti pick;                           YES
(h). Warding;                           NO
(i). Barrel/curtain;                    YES
(j). Anti drill;                            YES    
(k). KTB;                                 20MM