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Some problem creating gCode from Python with cura engine and JSONfiles


simonst
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Posted · Some problem creating gCode from Python with cura engine and JSONfiles

So after hours of painful forum post reading I managed to get a code running that lets me create a somewhat functioning gcode file. Idea of this project is to accelerate the whole workflow from .png image to 3D print: So my code takes an .png image, creates a greyscale mask of selected ROI, creates a .scad and .stl file with OpenSCAD and then by running the command:

command = [curaEngine, 'slice', '-j', myJSONfile, '-o', myGcode, '-l', mySTL] 

creates a gcode file.

 

The JSON file im inputting is a changed version of the anycubic_i3_mega_s.def.json file, where i add some settings like layer_height = 0.15 etc.

But for some reason i doesn't adjust all implemented changes: e.g. the skirt_brim_line_width is always 0.8mm when I check the gcode in ultimaker cura 4.11 although i specify it to be 0.4 (which is the Nozzle diameter) and it should be 0.4 by default anyway, as defined in the fdmprinter.def.json. The only brim setting it is applying is the brim_line_count somehow... I tried to look through the whole fdmprinter.def.json file which is inherited by myJSONfile to find a setting that might cause this issue, but couldn't figure it out. When i slice the created stl file with ultimaker cura 4.11 it works fine.

 

(Also for this whole process to work I had to save a copy of the inherited extruder json file to the same folder (/resources/definitions) as the printer file) 

 

If someone has some deeper knowledge on this topic i would be glad to hear from you. I attached the changed json file with all the overrides for the fdmprinter.def.json file and the output gcode file. The files it inherits can all be found in in the ultimaker installation folder (for me on windows:  Ultimaker/resources/definitions/)

 

code snippet that rewrites JSON files
#######################################################################################################
# Rewrite JSONfiles
#######################################################################################################


with open(JSONfile, 'r+') as f:
    data = json.load(f)
    data['overrides']["machine_start_gcode"]["default_value"] = "G21    ...
    
    data['overrides']["machine_end_gcode"]["default_value"] = "M104 S0  ....

                                 

    entry = {"layer_height": { "default_value": 0.15},


          "line_width": {"default_value": 0.4},

 

          "brim_width": {"default_value": 2.0},


          "skirt_brim_line_width": {"default_value": 0.4},

          "brim_line_count": {"default_value": 5},


          "adhesion_type": {"default_value": "brim"}}

 


    data["overrides"].update(entry)
    
### save copy to right folder
with open(savefile, 'w') as g: 
    g.seek(0)   
    json.dump(data, g, indent=4)
    

 

Question.zip

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    Posted · Some problem creating gCode from Python with cura engine and JSONfiles

    Only default_value is used by the engine. So if you set value to be "0.4" or "=some_other_setting", it will be ignored and default_value is used instead.

     

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    Posted · Some problem creating gCode from Python with cura engine and JSONfiles
    1 hour ago, nallath said:

    Only default_value is used by the engine. So if you set value to be "0.4" or "=some_other_setting", it will be ignored and default_value is used instead.

     

    Oh okay that's good to know! I was wondering if that is the case. but as you can see in the code snippet from my post above, I am only changing default_values, but e.g. skirt_brim_line_width = 0.4 (which should be the default anyway in fdmprinter.def.json) doesn't work somehow, while others work e.g. layer_height = 0.15.

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