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Arc Center Mode

Large Arcs when Loading GCode

If you are getting large arc and circles displayed in the tool path when you load the file most likely your the Arc Center Mode is not correct.  This means the GCode file you are loading is not specifying the mode its expecting Mach use when running the file.


There are two solutions to this problem:

  • Add a G90.1 for Absolute Arc Center Mode, or G91.1 for Incremental Arc Center Mode to the the top of your GCode files
  • Change the default mode Mach starts up in to the mode your GCode was written for.

To Change the default Arc Center Mode in Mach, Goto Configure -> Control and on the first tab Defaults select the desired mode.

Arc Center Mode.png

For more information on G90.1 and G91.1 take a look at the GCode Manual.