How to Crack a Master Lock- Combination Lock

A good way to open a combination lock.

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Step 1: How to Crack a Master Lock- Combination Lock

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    4 Discussions


    2 years ago

    This is a wonderful idea, but in practicality I really doubt it. I think this person knew the combination ahead of time. Inside the lock are three wheels which each have a slot in them, when you pull the shackle, there is a cam which needs to slide freely into the three aligned slots or it will not open.

    I don't know the correct terminology, I am not a locksmith, I just disassembled enough of these in high school to figure it out. How the combination works is, the first wheel is directly linked to the dial on the front (and it is the last number you will input) but the first wheel has a knob on the back of it which pushes a knob on the front of the second wheel, which has a knob on the back of it which pushes a knob on the front of the third wheel.

    Rotating the dial two full revolutions is how you get the third wheel to move, but when you reverse directions it stays wherever it stopped, and after one full revolution you are turning the second wheel in the opposite direction. As you reverse direction again and do the final rotation the second wheel stays wherever it stopped. The you rotate the first wheel until all of the slots in the wheels are lined up and in alignment with that cam I spoke of earlier.

    So this method shouldn't work, as you put tension on the shackle, the cam will be stopped from moving by 2 out of the three wheels.

    What you can do, if you're very very sensitive, is feel when the first wheel's knob touches the second wheel's knob and starts turning it. If you can do that, and then do it again for the third knob (either in the same direction or in reverse), you might be able to extrapolate the combination from this - but still, the first wheel is much harder to figure out, since it is directly linked to the dial. You might have to try aligning all three slots 40 times (one for every position of the first wheel) before they are correctly aligned with the cam.

    My method for "cracking" one was usually to drill through the back in a certain spot so I could see the wheels inside, and then just watch as the slots came into alignment. It still takes a long time!

    1 reply

    Reply 2 years ago

    I didn't think it would work as well... but i gave it a go and practiced some to get the feel of each of the points and i can attest this method has helped me get into at least 5 different locks.