BB 1.1 RC6 loses position

Discussion in 'Calibration, Help, and Troubleshooting' started by Proto_BB, Aug 4, 2016.

  1. Proto_BB

    Proto_BB Well-Known Member

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    I have a strange issue where for some reason after a print my BigBox can lose it's awareness of its current position. I do the mesh leveling, Safe to memory, do a print - all goes well. Then seemingly randomly the next print or one after it seems to lose its position on the X & Y (flashing on the LCD) and ends up ramming into the back wall when docking. Then it prints on one of the sides of the bed instead of center for the next print.

    I have no idea if this is an RC6 issue, or if it's an issue with the Rumba. The Rumba is unstable in that it will reset when performing the first command after a fresh start. After the reset its stable from then on. But why the reset in the first place? Why the losing position after a print and seemingly randomly ramming the docked position?

    Has anyone else seen either of these issues?
     
  2. TimV

    TimV Well-Known Member

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    Lots have been said and written about this, so have a look around on the forum if you want more details.
    Basically here is the short version.
    This happens when you have selected E1 and then did an auto-home, which makes the carriage bump in the back.
    There are some workaround, like using @Alex9779 firmware (which takes this into account in 99% of the cases) or selected E0 first (on OctoPrint) extruding 1mm (and when cold, it will not extrude anything because of the cold hotend protection) and then auto-homing.
    This will avoid collisions.
    Also, check out the S3D profile scripts (which would make you do the same thing before starting etc - also work from @Alex9779) and OctoPrint setup (which has some scripts which you can run under certain circumstances)

    Hope this helps you out, and if not, give a shout

    Greetz
    T.
     
  3. Alex9779

    Alex9779 Moderator
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    Actually the firmware does not help here as RC6 allows this issue to happen...
    It is just the profiles, more specific the scripts for start and end in there. The start does everything needed to bring the machine in a defined state and the end does everything to leave the machine in a defined state, that is T0 selected...
     
  4. Proto_BB

    Proto_BB Well-Known Member

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    Thanks Tim and Alex for clearing this up. I have been hacking my own GCode and could not see where I had gone wrong. I also was not sure if this was a by-product of my unstable Rumba which has incidentally blown one of the servo boards.

    I will try the suggested E0 first when cold and hopefully I never see it again.
     

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