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 simplest for individuals to wrap their heads round. That is your normal Cartesian format, through which the instrument head rides on linear rails alongside two or three axes. However there are various different kinematic programs, particularly when you begin using superior trigonometry. One instance of that comes from Mike Barkelew’s Scribble Buddy CNC Pen Plotter.
Virtually each different pen plotter you’ll see could have normal Cartesian kinematics: two stepper motors, two belts, and two linear rails/rods. Scribble Buddy is rather a lot completely different. It has a kinematic system that resembles the parallelogram linkage that you just’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 throughout the work space. The draw back is that it may possibly’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 aspect, it makes use of an Arduino Mega 2560 board to manage 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 normal 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 completely different kinematics.
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