dengshuibing / svgtogcode

Svg to Gcode - Flamma project

Don't feel like coding? Use the Inkscape extension.

This library's intended purpose is to laser-cut svg images. However, it is structured such that it can be easily expanded to parse other image formats or compile to different numerical control languages.

• Installation
• Documentation
  • Basic Usage
  • Custom interfaces
  • Insert or Modify Geometry
  • Approximation tolerance
  • Support for additional formats
• Contribution guidelines

Installation

Svg to Gcode is available on pip. To install it, execute:

pip install svg-to-gcode

Of course, you could also just download the sourcecode.

Documentation

The module is divided in three sub-modules:

• svg_to_gcode.geometry offers a general representation of geometric curves.
• svg_to_gcode.parser parses svg files, converting them to geometric curves.
• svg_to_gcode.compiler transforms geometric curves into gcode.

Basic Usage

If all you need is to compile an svg image to gcode, for a standard cnc machine, this is all the code you need. Just remember to select your own cutting and movement speeds.

from svg_to_gcode.svg_parser import parse_file
from svg_to_gcode.compiler import Compiler, interfaces

# Instantiate a compiler, specifying the interface type and the speed at which the tool should move. pass_depth controls
# how far down the tool moves after every pass. Set it to 0 if your machine does not support Z axis movement.
gcode_compiler = Compiler(interfaces.Gcode, movement_speed=1000, cutting_speed=300, pass_depth=5)

curves = parse_file("drawing.svg") # Parse an svg file into geometric curves

gcode_compiler.append_curves(curves) 
gcode_compiler.compile_to_file("drawing.gcode", passes=2)

Custom interfaces

Interfaces exist to abstract commands used by the compiler. In this way, you can compile for a non-standard printer or to a completely new numerical control language without modifying the compiler. You can easily write custom interfaces to perform additional operations (like powering a fan) or to modify the gcode commands used to perform existing operations (some DIY laser cutters, for example, control the laser diode from the fan output).

The code bellow implements a custom interface which powers on a fan every time the laser is powered on.

from svg_to_gcode.svg_parser import parse_file
from svg_to_gcode.compiler import Compiler, interfaces
from svg_to_gcode.formulas import linear_map

class CustomInterface(interfaces.Gcode):
    def __init__(self):
        super().__init__()
        self.fan_speed = 1
    
    # Override the laser_off method such that it also powers off the fan.
    def laser_off(self):
        return "M107;\n" + "M5;"  # Turn off the fan + turn off the laser

    # Override the set_laser_power method
    def set_laser_power(self, power):
        if power < 0 or power > 1:
            raise ValueError(f"{power} is out of bounds. Laser power must be given between 0 and 1. "
                             f"The interface will scale it correctly.")

        return f"M106 S255\n" + f"M3 S{linear_map(0, 255, power)};"  # Turn on the fan + change laser power

# Instantiate a compiler, specifying the custom interface and the speed at which the tool should move.
gcode_compiler = Compiler(CustomInterface, movement_speed=1000, cutting_speed=300, pass_depth=5)

curves = parse_file("drawing.svg") # Parse an svg file into geometric curves

gcode_compiler.append_curves(curves) 
gcode_compiler.compile_to_file("drawing.gcode")

Insert or Modify Geometry

Before compiling, you could append or modify geometric curves. I'm not sure why you would want to, but you can. The code below draws a fractal and compiles it to gcode.

Ups. Looks like this example was never filled in...

Approximation tolerance

Gcode only supports liner and circular arcs. Currently I've only implemented a line segment approximation. As such, geometric curves are compiled to a chain of line-segments. The exact length of the segments is adjusted dynamically such that it never diverges from the original curve by more then the value specified by TOLERANCES['approximation'].

The default value is 0.1. Smaller values improve accuracy, larger ones result in shorter gcode files.

from svg_to_gcode import TOLERANCES

TOLERANCES['approximation'] = 0.01

Support for additional formats

For now, this library only converts svgs to gcode files. However, its modular design makes it simple to support other formats. If you're looking to support a specific format, pull requests are always welcome. Just make sure to read CONTRIBUTING.md to get a feeling for the internal structure and best practices.