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Machine lost where it thinks it is?

Discussion in 'General Talk' started by Mark P, Sep 6, 2020.

  1. Mark P

    Mark P New
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    Hi everyone.
    I'm new here but I have my first issue using my CNC.
    I have a well built DIY CNC router with A raspberry PI , BCNC and an Arduino to run everything. The machine has limit switches on XYZ. When I first got the machine it homed and jogged with no issues. I've not touched it for some time and now it won't home or jog at all. When I tell it to go home it comes up with various errors. As I'm very much new to all this explaining isn't so simple but I'll try.
    Press Home. Error
    Jog. Error
    Both the same issues the machine goes in to alarm mode and stops the sequences. It looks as though it thinks it's going beyond the limits. The first thing I noticed after homing it is it went in the wrong direction instead of top right it went bottom left where there aren't any limit switches. It's as though the area it thinks it's in as moved out of position.
    As I said before I'd not touched it for a while it was fine but now it's not.
    Hopefully someone can point me in the right direction to fix this issue so I can start using and enjoying my machine.
    Thanks in advance.
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Telling is which errors specifically (code and wording) will help determine possible causes. There are many possible error messages , they do tell you why they popped up though so screenshot/write them down

    Did you have a backup of your Grbl settings from when you last used it to compare against the current settings (if not, likely redoing them will get it sorted, provided the error message do not relate to electronic/wiring related issues)
     
  3. Mark P

    Mark P New
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    IMG_1727.JPG IMG_1730.JPG IMG_1732.JPG IMG_1733.JPG IMG_1734.JPG IMG_1735.JPG IMG_1736.JPG IMG_1737.JPG IMG_1738.JPG IMG_1740.JPG IMG_1741.JPG IMG_1742.JPG IMG_1743.JPG IMG_1744.JPG IMG_1745.JPG IMG_1746.JPG IMG_1747.JPG IMG_1748.JPG IMG_1754.JPG The Thanks Peter.
    The people on this forum may have seen my machine before as the chap who I purchased it from said he'd been on here while he was building it.
    To answer your points with the spindle where it is in the photo as I can't move it from there.-

    Z up error 9, state G90, G-code locked out during jog or jog state.
    Z down, it will jog down but nowhere to go as low anyway.

    Y away (+) from the position it's in on the photo.
    state alarm 2, error G 91G0Y1. G-code motion state exceeds machine travel, machine position safely retained. Alarm may be unlocked.
    Y will jog towards the front (-) but again nowhere to go as it's already to the front.

    X (right)
    from the position it's in on the photo, state alarm 2, error G 91G0X1. G-code motion state exceeds machine travel, machine position safely retained. Alarm may be unlocked.
    X will jog left but again nowhere to go as it's already to the left.

    Homeing.
    Alarm 8.
    Homing fail. Cycle failed to clear limit switch when pulling off. Try increasing pull-off, check wiring.

    The work position, you can see on the photo it thinks its top right when it's bottom left.

    Hope this helps. I've checked for any loose wires or wires not in and can't see any. As I said I've not touched it for a while but it was working fine when I last shut it down.

    I've included photos of the settings it maybe that you can spot something wrong there.

    Many thanks.
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Caused by an earlier alarm/error that put Grbl into the locked mode. In this context you can ignore this error and focus on what error preceeded it which was the actual cause

    Either Max Travel or Homing Direction settings incorrect. Disable Soft Limits for now to help determine what exactly is wrong. Soft limits are tough on beginners, so only turn it on when homing, and everything else is working correctly (revisit Max Travel and homing direction after)

    Either steps per mm is way off and its moving less than commanded, or set Homing Pull-off to 10mm in Grbl settings

    Also check if you are wired normally open or normally closed, and adjust $5 (Invert Limits) accordingly. Not sure of bCNC but OpenBuilds CONTROL has a troubleshooting tab where you can test this easily. CONTROL might overall help you ease into the Hobby, lot friendlier than bCNC
     
  5. Mark P

    Mark P New
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    Thanks for the pointers,I'll work though those and see what happens.
    One more thing to point out. When I fist turned on the machine after it being idle for a while when I did an home it came hurtling towards me totally in the opposite and wrong direction (where it stands now) Totally unexpected. Wonder if this might suggest something?
     
  6. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Feels like corrupted Grbl settings. Redoing them if you had a backup would be a quick check
     
  7. Mark P

    Mark P New
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    Peter I'm at the very start of this cnc. journey. So I fully understand what I'm doing and why can you point me to a walk through on this. When you say back up do you me other than what's on the Arduino? This machine is second hand so I don't personally know about any backup.
    I'll email the person who built it.
    Many thanks.
     
  8. Mark P

    Mark P New
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    Note: I'm assuming your talking about grbl to the Arduino?
     
  9. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    If the history is dubious, i would recommend starting over.
    Refer to the Grbl Wiki

    But basically

    1) use $RST commands to reset the eeprom
    2) first setup steps per mm for accurate movement (at least good enough, if you have openbuilds leadscrews, and 1/8 microstepping (recommended) thats 200 steps per mm
    That will get you 'running' at least
    3) if any axes are going the wrong way when jogging, change $3 (easy to do in OpenBuilds-CONTROL)

    By the way i recommend setting the Pi anf BCNC aside too. Openbuilds CONTROL is a lot more beginner friendly see software.openbuilds.com

    Limits, homing and soft limits can trip up beginners, so don't enable it just yet :) build up some familiarity first, find your feet...

    Without limits/homing you can follow the Hello World tutorial which shows you basic CAM, Control, jogging, setting zero and running a first test job.

    See
     
  10. Mark P

    Mark P New
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    Thank you so much for this Peter. I have plenty of home work now to do. If nothing else it will be good to build up some knowledge. BTW. I do like the look of OB Control.
     
    Peter Van Der Walt likes this.
  11. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    From scratch is the best way to learn :)
    And thanks for the compliments on Control
     

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