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

Overview

Juicy-gcode is a configurable SVG to G-code converter that approximates bezier curves based on your needs:

• with biarcs for maximal curve fitting: bezier curves are approximated with arcs (G2, G3 commands), the resulting path is G1 continues
• 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 continues

Installation

The easiest way is to download one of the pre-built 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 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 derivation 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. In juicy-gcode these settings are called GCode flavor and consists 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 pen)
• Tool off (commands to switch the tool off e.g. lift pen)

These settings can be provided by a 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.

gcode
{
   begin = "G17;G90;G0 Z1;G0 X0 Y0"
   end = "G0 Z1"
   toolon =  "G00 Z1"
   tooloff = "G01 Z0 F10.00"
}

In the case you want to overwrite it, copy this favor to a text file and modify it according to your need. Then use juicy-gcode as follows:

$ juicy-gcode SVGFILE -f FLAVORFILE

Future development

Juicy-gcode was originally developed as a testbed for my hanging plotter project, but over the years it reached maturity and became a really usuable tool. My main idea for further development is to turn it into a tool that can drive CNCs in 2.5 dimensions (e.g. carving, engraving) with just one colored SVG file.

To be able to test and enjoy that software, I need a proper CNC. Please consider donating a small amount for that purpose, or donate an actual CNC if you have a spare one for whatever reason.

Donate for a CNC

Collected so far: 229.47€ Target: >= 209€

Thank you so much for all people supporting the development!

Limitations

SVG features that are not supported:

• texts
• filling
• clipping
• images