🖋️ Eric-Kapton: The Ender 3 2D Plotter

A high-precision 2D plotter conversion of a Creality Ender 3 Pro. This project features a complete "gutting" of 3D printing components—no hotend, no heated bed—creating a dedicated, lightweight, and silent drawing machine.

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🚀 Highlights

• Pure Plotter Build: All heaters and extruders have been removed to reduce weight and complexity.
• Sensorless Homing: Utilizing TMC2209 StallGuard on X and Y axes for a sleek build without physical limit switches.
• UART Communication: Direct serial connection between the Raspberry Pi Zero 2W and SKR Pico via /dev/ttyAMA0.
• Status Lighting: Integrated NeoPixel support for visual feedback (currently set to a purple/blue theme).

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🛠️ Hardware Specifications

Component	Specification
Printer Model	Creality Ender 3 Pro
Controller	BigTreeTech SKR Pico V1.0
Host	Raspberry Pi Zero 2W
Firmware	Klipper / Mainsail (via KIAUH)
X/Y Drivers	TMC2209 with Sensorless Homing
Z Endstop	Physical Switch on Pin gpio25
Pen Holder	Precision Linear Pen Holder

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📂 Plotter Configuration & Macros

The machine logic is split between printer.cfg for motion and macros.cfg for plotter-specific workflows.

Motion & Homing

• X/Y Sensitivity: Both axes are tuned with a driver_SGTHRS of 80 for reliable sensorless homing.
• Speed: Optimized for plotting with a max_velocity of 250 and max_accel of 5000.
• Z-Axis: Repurposed to act as the pen lift with a position_min of -7 to allow for varied surface heights.

Essential Macros

• PEN_UP: Lifts the pen to 10.0mm.
• PEN_DOWN: Lowers the pen to 0.2mm for drawing.
• START_PRINT: Homes the machine and moves the toolhead to the center of the bed, waiting 10 seconds for pen attachment/adjustment.
• END_PRINT: Gently lifts the pen and slides the bed forward to "present" the finished drawing.

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🔌 UART Wiring Reference

The Raspberry Pi Zero 2W is connected directly to the SKR Pico via the dedicated serial header.

• Serial Interface: /dev/ttyAMA0
• Baud Rate: 250000 (default)

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🔧 Installation

1. Install Klipper via KIAUH.
2. Flash the SKR Pico to communicate over UART.
3. Deploy the provided printer.cfg and macros.cfg to your config folder.
4. Calibrate your Z-offset for your specific pen tip using Z_ENDSTOP_CALIBRATE.

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🤝 Credits

• Developer: Sabitech
• Firmware: Klipper
• Interface: Mainsail
• Pen Mount: Design via MakerWorld