For most people, forgetting the combination on a lock means breaking out the bolt cutters and chopping off the lock. Some students at the [Olin College of Engineering] decided there was a far more elegant way to do the job, so they built an automated lock-cracking machine.
The machine consists of a clamp to hold the lock, a solenoid to pull the lock open, and a stepper motor to run through the combinations. Most of the processing is done on the attached computer, using software they created. The application will brute-force all of the possible combinations if you request it, but it also allows you to enter the first, second, or third numbers of the combination if you happen to remember them.
Once the machine is started, the motor begins spinning the lock and the solenoid yanks on the latch until the combination is discovered, which takes a maximum of about two hours to complete. The opening of the latch trips a limit switch and causes the mechanism to stop. A simple button press then returns the lock’s combination to the user.
Be sure to check out the video embedded below of the lock cracker in action.