A CNC pen plotter with very uncommon kinematics
February sixth, 2023—
The overwhelming majority of automated, CNC-controlled machine instruments make the most of a kinematic movement system that’s (not coincidentally) the best for individuals to wrap their heads round. That is your commonplace Cartesian structure, through which the instrument head rides on linear rails alongside two or three axes. However there are numerous different kinematic programs, particularly when you begin using superior trigonometry. One instance of that comes from Mike Barkelew’s Scribble Buddy CNC Pen Plotter.
Nearly each different pen plotter you’ll see can have commonplace Cartesian kinematics: two stepper motors, two belts, and two linear rails/rods. Scribble Buddy is lots totally different. It has a kinematic system that resembles the parallelogram linkage that you simply’ll see on one thing like a pantograph, however with the 2 linkage ends hooked up to motorized wheels. By rotating these wheels to particular angles, the machine can change the geometry of the linkage and transfer the pen to any location inside the work space. The draw back is that it might probably’t draw completely straight traces. The profit is that it’s fascinating and funky.
Scribble Buddy’s construction is a mix of wooden and 3D-printed mechanical components. On the electronics facet, it makes use of an Arduino Mega 2560 board to regulate the 2 wheel stepper motors and the servo motor that lifts the pen. Corridor Impact sensors give Scribble Buddy closed-loop suggestions for exact positioning. The management interface consists of an LCD display, a sliding potentiometer, a rotary encoder, and a joystick. Scribble Buddy accepts commonplace G-code and makes use of formulation to transform the instructions into wheel rotation that works for this kinematic system.
From a sensible perspective, Scribble Buddy has little or no utility. However it’s all the time nice to see makers experimenting with totally different kinematics.