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G71 Gcode

Posted: Tue May 21, 2019 1:50 pm
by mthomas
Using qcad set for GRBL (mm) almost always generates a G71 G91.1 line in the exported gcode header. The G91.1 is fine but G71 just stops the controller, always need to manually edit the generated file and remove it. Any ideas as to why this is happening, G71 in the case of standard mil/drill operations doesn't make sense.

Re: G71 Gcode

Posted: Tue May 21, 2019 1:59 pm
by andrew
G71 sets the unit of the controller to Millimeter.

You can simply create your own post processor in the "postprocessors" directory as follows:

File name: "MyGrblMM.js"
File contents:

Code: Select all


function MyGrblMM(documentInterface, camDocumentInterface) {, documentInterface, camDocumentInterface);

    this.decimals = 4;
    this.unit = RS.Millimeter;
    this.outputOffsetPath = true;

    this.header = [
        "[N] G21 G17 G90 G40 G49 G80",
        "[N] G91.1"

MyGrblMM.prototype = new Grbl();
MyGrblMM.displayName = "My Grbl (offset) [mm]";
The choos the post processor "My Grbl (offset) [mm]".

Re: G71 Gcode

Posted: Tue May 21, 2019 2:05 pm
by mthomas
Thanks for the quick response. I would have thought G21 would set up metric but good to know the header can be altered.