It’s official: [Engineer Bo] wins the internet with a video titled “Finding NEMA 17,” wherein he builds a dynamometer to find the best stepper motor in the popular NEMA 17 frame size.

Like a lot of subjective questions, the only correct answer to which stepper is best is, “It depends,” and [Bo] certainly has that in mind while gathering the data needed to construct torque-speed curves for five samples of NEMA 17 motors using his homebrew dyno. The dyno itself is pretty cool, with a bicycle disc brake to provide drag, a load cell to measure braking force, and an optical encoder to measure the rotation of the motor under test. The selected motors represent a cross-section of what’s commonly available today, some of which appear in big-name 3D printers and other common applications.

[Bo] tested each motor with two different drivers: the TMC2209 silent driver to start with, and because he released the Magic Smoke from those, the higher current TB6600 module. The difference between the two drivers was striking, with lower torque and top speeds for the same settings on each motor using the TB6600, as well as more variability in the data. Motors did better across the board with the TBC6600 at 24 volts, showing improved torque at higher speeds, and slightly higher top speeds. He also tested the effect of microstepping on torque using the TBC6600 and found that using full steps resulted in higher torque across a greater speed range.

At the end of the day, it seems as if these tests say more about the driver than they do about any of the motors tested. Perhaps the lesson here is to match the motor to the driver in light of what the application will be. Regardless, it’s a nice piece of work, and we really appreciate the dyno design to boot — reminds us of a scaled-down version of the one [Jeremey Fielding] demonstrated a few years back.

We all know the Hollywood trope of picking a lock with a paperclip, and while it certainly is doable, most reputable locks require slightly more sophisticated tools to pick effectively. That’s not to say that wire is off the table for locksports, though, as this cool lock-picking robot demonstrates.

The basics behind [Sparks and Code]’s design are pretty simple. Locks are picked by pushing pins up inside the cylinder until they line up with the shear plane, allowing the cylinder to turn. Normally this is done a pin at a time with a specialized tool and with a slight bit of torque on the cylinder. Here, tough, thin, stiff wires passing through tiny holes in a blade shaped to fit the keyway are used to push all the pins up at once, eliminating the need to keep tension on the cylinder to hold pins in place.

Sounds simple, but in practice, this looks like it was a nightmare. Getting five wires to fit into the keyway and guiding them to each pin wasn’t easy, nor was powering the linear actuators that slide the wires in and out. Applying torque to the lock was a chore too; even though tension isn’t needed to retain picked pins, the cylinder still needs to rotate, which means moving the whole picking assembly. But the biggest problem by far seems to be the fragility of the blade that goes into the keyway. SLA might not be the best choice here; perhaps the blade could be made from two thin pieces of aluminum with channels milled on their faces and then assembled face-to-face.

The robot works, albeit very slowly. This isn’t [Sparks and Code]’s first foray into robot lock picking. His previous version attempted to mimic how a human would pick a lock, so this is really thinking outside the box.