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IndustryArena Forum > OpenSource CNC Design Center > Raspberry Pi CNC > New System, Different Units for Jog and GCode Program
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  1. #1
    Join Date
    Jun 2013

    New System, Different Units for Jog and GCode Program

    Hey all, I just switched the electronics for my G0704 CNC machine from LinuxCNC with a ghetto old computer to a Raspberry Pi 3B+ with bCNC and GRBL. I've got everything all configured and was doing all my testing with jogging. Machine is set up for inch measurements. I loaded a simple test program and ran it and found that, while Z moves the correct units each time, X and Y are both only moving half the distance of that specified by the program. I am not using any micro stepping and my configuration also assumes no micro stepping. I changed the number of pulses per distance to twice the number, but when it rapids to the start point, it goes twice as far! So to boil it down:

    - Jog and rapids move the correct distance
    - G1 movements are only going half the distance

    Here is a snippet of my header. I don't see anything here that should result in this. Any ideas?

    G0 Z0.125
    ( T0 : 0.1875 )
    T0 M6
    ( Profile1 )
    M3 S1000
    G0 X-1.6843 Y0.2347
    G0 Z0.0625
    G1 F10.0 Z-0.125
    G1 F12.0 X-1.3773
    G3 X-1.2835 Y0.3285 I0.0 J0.0938
    G1 X-1.2837 Y0.6717
    G1 X1.258
    G1 Y0.3285

  2. #2
    Join Date
    Jun 2013

    Re: New System, Different Units for Jog and GCode Program

    Alright, so apparently there needs to be a factor of 2 in there somewhere, and my GRBL controller was also out of sync. I've got it all resolved now, but I still don't understand where my factor of two magically came from. Oh well, we're moving right along, nothing to see here.

  3. #3

    Re: New System, Different Units for Jog and GCode Program

    Seems like you found the problem. But just in case you still have it you may have to calibrate GRBL to your machine. There is a few videos on how to do it.

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