Sketchbot

Sketchbot is a robot that can draw text and images on 3 x 5 inch post-it notes. It leverages MarIOnette and a custom-build node group inside Blender’s geometry nodes (similar to Grasshopper in Rhino) in order to dynamically generate motion. The user can input any text or .SVG image and the robot does the rest! This project was born out of a desire to experiment with brushless motor motion control and attempt to create tool paths in a more dynamic and visual way. The robot is controlled with a single Teensy 3.2 microcontroller that sends commands to the motors over CAN bus.

Sketchbot has a servo-driven pen lifting mechanism. The pen is sprung so that it always contacts the paper, and the entire carriage moves on a small linear bearing in order to minimize pen deflection.

Sketchbot has a servo-driven pen lifting mechanism. The pen is sprung so that it always contacts the paper, and the entire carriage moves on a small linear bearing in order to minimize pen deflection.

I created a custom node group using Blender's Geometry nodes environment. It takes an image or text input, converts it to curve objects, and then iterates and draws along each curve. The setup also accounts for pen travel between curve objects. Just

I created a custom node group using Blender's Geometry nodes environment. It takes an image or text input, converts it to curve objects, and then iterates and draws along each curve. The setup also accounts for pen travel between curve objects. Just like a CNC jog motion, the pen lifts, moves, and then lowers between curves. Finally, each curve can be drawn with easing in order to limit any sudden movements and provide more smooth motion of the pen.

Sketchbot uses two GIM-6010-8 brushless motors. These include dual encoders, an O-Drive controller, and an 8:1 planetary reducer. In order to get more resolution and enhance the robot's drawing capabilities, I use a custom 5:1 GT2 belt reduction. The

Sketchbot uses two GIM-6010-8 brushless motors. These include dual encoders, an O-Drive controller, and an 8:1 planetary reducer. In order to get more resolution and enhance the robot's drawing capabilities, I use a custom 5:1 GT2 belt reduction. The final repeatability of the robot turned out to be under .25mm, which I was happy with given the plastic links.

All joints inside the arms contain at least two deep groove ball bearings. In order to eliminate any play in the bearings, they are pre-loaded with some custom caps.

All joints inside the arms contain at least two deep groove ball bearings. In order to eliminate any play in the bearings, they are pre-loaded with some custom caps.

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