Juicy-gcode: A lightweight 2.5D SVG to GCode converter for maximal curve fitting

Overview

Juicy-GCode is a command-line application that converts SVG files to GCode. It provides flexible options for curve approximation and allows configurable GCode generation based on color information.

Features

• Configurable Curve Approximation: Juicy-GCode offers three approximation methods to suit your needs
  • with biarcs for maximal curve fitting: bezier curves are approximated with arcs (G2, G3 commands), the resulting path is G1 continuous
  • with linear approximation when arcs are not supported by your firmware: bezier curves are approximated with line segments (G0, G1 commands), the resulting path is not smooth, and the generated GCode is usually significantly larger
  • with cubic bezier curves if your firmware supports it: some firmwares (e.g. Marlin) can handle bezier curves directly (G5 command), the result is G2 continuous
• Configurable 2.5D GCode generation: Juicy-GCode allows you to configure the GCode generation by color information (this feature enables e.g. carving of 3D objects based on a single SVG file)
  • extra GCode can be added to the beginning of a continous colored path
  • GCode parameters e.g. E, F or S can be set per color
  • the number of passes can be set for a given color (upcoming feature)

Installation

The easiest way is to download one of the prebuilt binaries from the releases page. Alternatively, you can build from source code as follows:

• Install Stack if you do not have it yet
• $ git clone https://github.com/domoszlai/juicy-gcode.git
• $ stack build
• $ stack install
• $ juicy-gcode --help

Usage

⚠️ Breaking change: Since version 1.0.0.0, the flavor file format changed to YAML. If you use a pre 1.0 version, please refer to this historical README file

⚠️ Breaking change: Since version 0.3.0.0, --generate-bezier has been removed in favor of the more generic --curve-fitting parameter and --resolution has been renamed to --tolerance

⚠️ Breaking change: Since version 0.2.0.1, default DPI is changed to 96 and the option to mirror the Y axis is removed (it is always mirrored now for correct result)

The easier way to use juicy-gcode is to simply provide an SVG file name. The generated GCode will be written to standard output. The default approximation method is the biarcs based.

$ juicy-gcode SVGFILE

Alternativly, you can provide an output file name as well.

$ juicy-gcode SVGFILE -o OUTPUT

Sometimes you want to overwrite some default settings. These are the

• --dpi (default 96 DPI) the resolution of the SVG file that is used to determine the size of the SVG when it does not contain explicit units
• --tolerance (default is 0.1 mm) maximum allowed deviation of the approximation curve

$ juicy-gcode SVGFILE --dpi 72 --tolerance 0.01 

Curve fitting options (default is biarc):

$ juicy-gcode SVGFILE --curve-fitting=biarc

$ juicy-gcode SVGFILE --curve-fitting=linear

$ juicy-gcode SVGFILE --curve-fitting=cubic-bezier

Configuration

The generated GCode is highly dependent on the actual device it will be executed by and one might also want to generate different GCode for different colors. In juicy-gcode these settings are called GCode flavor and consist of the following:

• Begin GCode routine (commands that are executed before the actual print job)
• End GCode routine (commands that are executed after the actual print job)
• Tool on (commands to switch the tool on, e.g. lower the pen)
• Tool off (commands to switch the tool off e.g. lift the pen)
• Color dependent settings

These settings can be provided by a YAML configuration file. The default settings are made for being able to test the generated GCode in an emulator e.g. with LaserWeb or my hanging plotter simulator.

begin: |
  G17
  G90
  G0 Z1
  G0 X0 Y0
end: |
  G0 Z1
toolon: |
  G01 Z0 F10.00
tooloff: |
  G00 Z1

By providing your own configuration file, you can also specify color dependent settings. As an example, the following configuration adds extra GCode configuration for the color codes #000000 and #FF0000.

colors:
   "000000": 
      before: |
        ; black
      passes: 1
      parameters:
        F: 1.0 
        S: 80
   "FF0000": 
      before: |
        ; red
      passes: 1
      parameters:
        F: 2.0 
        S: 25

In this example, GCode comments will be generated before any continous red or black path, the F and S GCode parameters are set different for red and black paths (and not set for any other colors) and the number of passes are set to 1 for both colors (passes is an upcoming feature, currently this option is ignored)

Use the -f option to pass the GCode flavor to juicy-gcode:

$ juicy-gcode SVGFILE -f FLAVORFILE

Limitations

SVG features that are not supported:

• texts
• filling
• clipping
• images