In a project, repetitive tasks that break the flow of development work are incredibly tiresome and even simple automation can make a world of difference. [Simon Merrett] ran into exactly this while testing different stepper motors in a strain-wave gear project. The system that drives the motor accepts G-Code, but he got fed up with the overhead needed just to make a stepper rotate for a bit on demand. His solution? A grbl man-in-the-middle jog pendant that consists of not much more than a rotary encoder and an Arduino Nano. The unit dutifully passes through any commands received from a host controller, but if the encoder knob is turned it sends custom G-Code allowing [Simon] to dial in a bit acceleration-controlled motor rotation on demand. A brief demo video is below, which gives an idea of how much easier it is to focus on the nuts-and-bolts end of hardware when some simple motor movement is just a knob twist away.
[Simon]’s jog pendant moves a single motor which is exactly what he needs to ease development of his 3D printed strain-wave gear using a timing belt, but it could be programmed with any G-Code at all. Speaking of DIY jog pendants for CNC machines, don’t forget this wireless one made from an Atari 2600 joystick that jogs a plasma cutter in X and Y, and zeroes it with a push of the button.