Welcome to Our Community

Some features disabled for guests. Register Today.

Is it possible for grbl to detect if an axis was moved manually

Discussion in 'Control Software' started by ZCNC, Sep 24, 2021.

  1. ZCNC

    ZCNC New
    Builder

    Joined:
    Sep 24, 2021
    Messages:
    11
    Likes Received:
    3
    Hello to all,

    I am trying to reduce homing in my program, for example between two executions of a set of gcode.
    Each time it should homing before another job to avoid inaccurate position caused by voluntary or accidental manual movement of an axis.
    But homing is slow and increases the execution time.
    So I thought of skipping a homing if nothing has changed, i.e. if no axis has been moved since the last command of the last gcode set (gcode file).
    Is it possible to know that?
    I use Grbl.
     
  2. Alex Chambers

    Alex Chambers Master
    Moderator Builder

    Joined:
    Nov 1, 2018
    Messages:
    2,681
    Likes Received:
    1,321
    If you have $1=255 your stepper motors will be energised when idle, so you shouldn't have to re-home between jobs. Manually moving an axis (knocking it with your arm) shouldn't be possible, and jogging it with your control software will not lose your workplace coordinates.
    What is "forcing" the re-homing? If it's part of your g-code let us know what cad/cam software you are using and which post processor.
    Alex.
     
    ZCNC and Peter Van Der Walt like this.
  3. ZCNC

    ZCNC New
    Builder

    Joined:
    Sep 24, 2021
    Messages:
    11
    Likes Received:
    3
    Thanks the $1=255 may be useful on some cases. Actually the operator may wait a long period of time before doing the next job while the CNC is ON. So in that case i can not use it because i do not want the stepper motor to be engaged all the time.
    "the re-homing" is not part of any software, I force the homing by my self in my python script.
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    Why not, its highly recommended.
     
    Alex Chambers likes this.
  5. ZCNC

    ZCNC New
    Builder

    Joined:
    Sep 24, 2021
    Messages:
    11
    Likes Received:
    3
    I was thinking about the longevity of the motor but if it has no impact so why not.
     
    #5 ZCNC, Sep 24, 2021
    Last edited: Sep 24, 2021
    Peter Van Der Walt likes this.
  6. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    Absolutely :) thats what they are made for
     
  7. Giarc

    Giarc OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Jan 24, 2015
    Messages:
    2,898
    Likes Received:
    1,613
    I speed up homing by jogging the machine to where the homing switches are so it only travels at the homing speed for a few millimeters. It will still be a delay, but much shorter.
     
  8. Alex Chambers

    Alex Chambers Master
    Moderator Builder

    Joined:
    Nov 1, 2018
    Messages:
    2,681
    Likes Received:
    1,321
    I sometimes have to tweak a design during a job. My cnc is in my cellar, my design PC is in my attic and I'm old:(. I leave the machine for 1/2 hour or more sometimes - it's not an issue - the stepper motors don't even get hot.
    Alex.
     
  9. ZCNC

    ZCNC New
    Builder

    Joined:
    Sep 24, 2021
    Messages:
    11
    Likes Received:
    3
    Thanks again Alex, i can say problem solved.
    @Giarc actually i did same like you, now with $1 setup homing delay is not anymore an issue.
     
    Giarc likes this.
  10. David the swarfer

    David the swarfer OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Aug 6, 2013
    Messages:
    3,239
    Likes Received:
    1,815
    if the machine is waiting for long periods then do a command like
    G21 G90 G53 G0 X-10 Y-10 Z-10
    before the wait, then the homing only needs to travel 10mm to the switches, then you can retain your power saving setting, or even turn off the stepper power supply between jobs.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice