Recovering Combinations for Open Combination Locks

Method 1: Viewing the cams to recover the first and second numbers

On Master Locks, if the latch is pushed back on an open lock, it is possible to view the cams and recover enough information to construct the combination. The cams may or may not be visible on other manufacturers' locks.

If the lock has a key cylinder and has been opened with the key, turn the key to pull the latch back to view the cams inside the lock. If the lock cylinder has been picked (see our page for picking the cylinder), use the tension wrench to turn the cylinder.

If the lock doesn't have a key cylinder or hasn't been opened using the key cylinder, it will be necessary to improvise to push the latch back for viewing the cylinders.

This video of a wooden combination lock demonstrates the concept:

 

 

 

 

 

 

 

 

In the Master Lock, you will be able to see the back and middle cams (called "rotors" in the video.) The video of the wooden demonstration lock shows what to look for inside the lock. You should be able to see both the notches in the cams and the "tabs" between the "rotors."

Rotate the dial fully right (clockwise) two turns, and stop when the notch on the cam closest to the back of the lock is fully visible. Record the number. Now, rotate the dial left (counterclockwise) one turn and continue until the notch on the middle cam is even with the notch on the back cam. Record this number as a second number.

These two numbers line up the notches on the middle and back cams, but not under the pawl. It is necessary to adjust both numbers to get the notches in the right place to open the lock. The actual first and second numbers will be about 10 marks on the lock dial to the left of the numbers you recorded.

Example, I get 16 for my first number and 6 for my second number. My first number is 6 and second number is 36 (or close to those numbers.)

Before closing the lock, use this second method for recovering the first number:

Method 2: Recovering the first number only

Drop the shackle lightly into the well on the lock body, but not far enough to lock. Hold the shackle down very lightly with a finger or thumb, again being very careful not to close the lock, and turn the dial left. At some point, which may require 2-3 turns, turning the dial should start to push the shackle up. This spot will be about 10 to 12 marks to the right, on the lock dial, of the first number in the combination, and will vary from lock to lock. Thus, if the shackle starts to push up at 36, the first number is 6 or close to 6.

Before closing the lock, check to see if the two methods recover first numbers that are close to each other.

Constructing the combination

If you have both the first and second numbers, dial them in the normal way, then pull up lightly on the shackle and turn right until the dial stops. Pull up on the shackle. If the lock doesn't open, release the shackle and turn right a little past where the dial stopped, then pull up lightly on the shackle and turn right until the dial stops. Pull up on the shackle again and see if the lock opens. Continue until you have gone all the way around the lock dial. If the lock still doesn't open, try first and second numbers that are 9 away on the lock dial from the numbers you found in method 1. If still no luck, try 11 away. Continue trying 8 away, 12 away, etc.

If you only have the first number, dial it in the normal manner, then left one turn and stop two marks to the right of your first number on the lock dial. Then, right, using the method in the previous paragraph. If the lock doesn't open, left until 6 marks past your first number and right, attempting to open the lock. Continue trying 10 marks past the first number, then 14, 18, 22, 26, 30 and 34 as needed If the lock does not open, try first numbers on both sides of the first number that you tried.

If you would like to learn more about the wooden combination demonstration lock, please visit http://woodgears.ca/combolock/index.html (Note: you are leaving the masterunlocked.com site.)

Detailed instructions for constructing the wooden demonstration lock are offered for sale on that site, but not the actual lock.

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