MIT students Grant Jordan and Kyle Vogt found themselves in possession of a high-security safe -- the S&G 8400, a class-1 safe of the sort formerly used to store classified documents. They wanted to open it, but they lacked the combination and were unable to crack it using the sort of techniques that work on lesser strongboxen. So they build a safecracking robot that autodialled combination after combination (the robot excluded "impossible" combinations that couldn't be set due to material limitations of the mechanism, which substantially reduced the keyspace). They eventually opened the safe, but didn't find anything interesting in it.
We used a custom stepper motor to rotate the dialer head. The dialer head transmits torque to the dial via a piece of heavy duty surgical tubing. The stepper motor we chose has more than enough resolution to implement our algorithm, but it's not quite as fast as it could be. Stepper motors have an extremely high "holding torque", which is ideal in this situation since the dial must be held in place while the butterfly knob is being turned.
The head also contains an RC servo motor with a machined knob to mesh with the butterfly knob. This setup enables independent rotation of both the dial and butterfly knob. The stepper motor shaft is also connected to a high resolution optical encoder for position feedback. The encoder is mainly used to detect when safe is successfully opened. The torque required to open the safe when the correct combination is entered is much higher than the maximum torque of the stepper motor, so the encoder is programmed to report when the position error exceeds a certain threshold. Basically, the stepper motor stalls and the encoder flips out if the safe actually opens.
This smallish portable USB charger from Kmashi is rated at 5000mAh and is on sale now for $8.38 when you use promo code: PIRVWBWG on Amazon. I have a few different Kmashi chargers, and have used them for over a year with good results.
The flashlights in our household have a tendency to wander off. Where do they go? I gave my last remaining one to my daughter for a camping trip, so I just reordered an 8-pack of metal LED flashlights for $14. Each flashlight has 9 LEDs and uses 3 AAA cells (included, though some reviewers on […]
Unlike a multimeter, this battery tester isn’t battery powered. Instead, it measures the voltage across the terminals of 9V, AA, AAA, C, D and 1.5V button type batteries. It’s also easier to use than multimeter probes. It’s only $6.61 on Amazon and has a 4.5 star rating with over 1500 reviews.
It’s time for a power upgrade — throw out that tired-out power strip and swap in this family-size USB charger, packed with 6 high-speed ports. With a built-in control chip, Kinkoo optimizes each port to ensure the fastest charging possible for all your devices. The Kinkoo is made from high-grade and durable materials so you […]
Watching Netflix, Hulu or other streaming services can unfortunately be difficult while traveling outside the US. Rather than bypass these restrictions with the help of a complex and slow VPN, choose a faster and simpler solution with Getflix. Instead of rerouting all your Internet traffic through a different server, this handy service only routes the […]
Shake, stir, and muddle your way to delicious homemade cocktails with this must-have bar set. Expect only the finest quality tools from MakersKit — enabling you to unleash your inner mixologist.Top 12 Favorite Things of 2014, Sunset MagazineQuart-size vintage-style Mason jar shakerRetro double jigger for accurate measurementsStrainer & spouts for a mixologist-style smooth pourHardwood muddler […]