1. Got a question or need help troubleshooting? Post to the troubleshooting forum or Search the forums!

Solved R1+ using MC - how determine Z offset?

Discussion in 'Troubleshooting' started by Wesley Knapp, Feb 12, 2019.

  1. Wesley Knapp

    Wesley Knapp Member

    Joined:
    Jan 19, 2019
    Messages:
    78
    Likes Received:
    32
    I've read every post I can find on the Z offset and now I'm just "meh".

    Seems though Evey post is about different slicers, different gcode options, etc etc etc, but I couldn't find a definitive answer on how one actually determines where the number comes from that one enters in any of these places.

    So with my specific printer (R1+) and MC, can someone lead me down this specific process path?

    TIA

    Sent from my Pixel XL using Tapatalk
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,141
    Likes Received:
    6,998
    For the stock Marlin firmware the CORRECT way to do this has never changed.
    Add the commands to the startup Gcode script.
    The M565 must be AFTER the last G28 and before the G29

    Here is an example:

    G28 ; home all axes
    M565 Z-1.0 ; set the offset for auto-leveling mechanism will need to be tuned for your printer
    G29 ; run auto-level
     
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,141
    Likes Received:
    6,998
    Some slicers have ways to set this in the UI but across versions it has been inconsistent and most offer a global "Z offset" which is not the same and does not get used in the autoleveling calculations.

    Newer versions of Marlin (1.1.x) do NOT use the M565, but the stock Robo 1.0.x version does

    You need to do 1 layer test prints to adjust your Z offset until your first layer looks like this:

    https://printedsolid.com/blogs/news/tagged/first-layer
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,141
    Likes Received:
    6,998
    That Z offset you figure out will not change until you change something on the hotend (new nozzle or new hotend) anything that mechanically tweaks the nozzle. Rerun tests after doing that sort of change and adjust the number as needed.
     
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,141
    Likes Received:
    6,998
    The main reasons to put it in the startup GCode block are that :
    1) every slicer has one so even changing slicers you can rely on this methid
    2) there is no worries about how the slicer implemented this changing from one version to the next

    Remember the slicer will update to keep up with new features and the Marlin firmware is NOT usually getting updated and if you are not careful the slicer may assume you are on a more current flavor of Marlin and use the wrong GCode

    Now, if you ARE on the 1.1.x branch (or 2.x even) of Marlin (non-stock R1 firmware) then presumably you know what you are doing and then it is on you however you want to setup the offset (you will not be using the M565 at any rate -- there are new commands for this in the later Marlin releases)
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,141
    Likes Received:
    6,998
    For new folks this can be a challenge if they try and read too many threads on newer versions of firmware and we try to keep the questions about those non-stock versions isolated to threads that clearly say which version of Marlin is being discussed :) But that is hard to keep clear sometimes.
     
  7. Wesley Knapp

    Wesley Knapp Member

    Joined:
    Jan 19, 2019
    Messages:
    78
    Likes Received:
    32
    This is what I'm asking. How to tune?

    Sent from my Pixel XL using Tapatalk
     
  8. Wesley Knapp

    Wesley Knapp Member

    Joined:
    Jan 19, 2019
    Messages:
    78
    Likes Received:
    32
  9. Wesley Knapp

    Wesley Knapp Member

    Joined:
    Jan 19, 2019
    Messages:
    78
    Likes Received:
    32
    Mark I truly appreciate your effort to assist me here but these are the same things I read previously that have provided no definitive answer to my question.

    I have:
    stock R1+ with RoboV2 firmware
    I'm using latest version of MatterControl.

    I'm not at this time concerned with any other firmware or slicer or hot end. Just a total stock R1+.

    With that said.

    I have a feeler gauge and am ready to determine the exact distance for the Z Offset setting. What are the steps to accomplish this?


    Sent from my Pixel XL using Tapatalk
     
  10. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
    Staff Member

    Joined:
    Feb 18, 2015
    Messages:
    5,806
    Likes Received:
    3,521
    Set the offset as mentioned above, connect to the printer via USB. issue a G28 in the MC terminal, then issue a G1 Z0 in the terminal, use the feeler to see if you can slide the gauge under the nozzle, If you can't then decrease (more negative) the number for M565, for example if you started with Z-1.0 as described, try Z-1.2, if there is a ton of room under the nozzle then increase the number (less negative) for example Z-0.8 then try the G28 followed by the G1 Z0 again.

    I do not use mattercontrol so this is just a rough outline of how you would set the offset, not a step by step.
     
  11. Wesley Knapp

    Wesley Knapp Member

    Joined:
    Jan 19, 2019
    Messages:
    78
    Likes Received:
    32
    So is the point of the of the offset to place the nozzle as close as possible to the bed after the bed leveling process or to place the nozzle at the level needed for first layer printing after ABL?

    Sent from my Pixel XL using Tapatalk
     
  12. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
    Staff Member

    Joined:
    Feb 18, 2015
    Messages:
    5,806
    Likes Received:
    3,521
    Close to the bed, remember the trigger for the Z endstop is below the level of the bed because the switches used must be deactivated (unclicked) and that won't happen until the weight is removed from the X carriage (left and/or right). The first layer height should be what you specify and only adjust M565 if you require more or less adhesion.
     
    Wesley Knapp likes this.
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,141
    Likes Received:
    6,998
    Here is the picture FROM that link :) (you do have to click on the embedded link on getting your prints to stick)

    blog_first-layer-example-small.jpg

    If you print a single layer test print and adjust your Z offset you will affect how that print looks (how well your first layer is applied). You want it to look similar to that. It takes practice.

    In practice the Z offset is merely there to account for differences in how each printers switches and sensors react/work and allow you to get a precisely put-down first layer which really affects how the rest of the model will look.
     
    #13 mark tomlinson, Feb 14, 2019
    Last edited: Feb 14, 2019
    Wesley Knapp likes this.
  14. Wesley Knapp

    Wesley Knapp Member

    Joined:
    Jan 19, 2019
    Messages:
    78
    Likes Received:
    32
    Thank you for the clarification. Yes, my prints do look like this. However, since my second print on this printer, I have always paused the print as soon as the last ABL point has been made and then lowered the Z by manually rotating the threaded rod CCW by 3 step bumps on each side. It has worked every time. So I decided to do this with Z offset since that was my understanding of the reason for the Z offset setting. Unfortunately, since this attempt to get the setting correct I've had nothing but problems with the 1st layer. Even resetting to the original offset it doesn't seem to work any longer. - "If it ain't broke, don't fix it."

    Sent from my Pixel XL using Tapatalk
     
  15. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,141
    Likes Received:
    6,998
    What you are describing is a global Z offset (manually applied, but still) and if that works perfect everywhere you are fine. You could still use the autoleveling offset to correct this or let the slicer do it with a global. The difference is not obvious since the M565 affects the calculated level plane and the global one is, well, global and does not affect the level calcs. It is applied "globally" afterward.

    Either approach is fine if you are OK with the results. You may at some point want to revisit this and get it working if things change.
     
    Wesley Knapp likes this.
  16. Wesley Knapp

    Wesley Knapp Member

    Joined:
    Jan 19, 2019
    Messages:
    78
    Likes Received:
    32
    Holy smokes I think you just ID'd my misunderstanding resulting in my error. So M565 is applied always and any offset set in the MC options OTHER than the G-code settings are applied after ABL and before extrusion starts. I was entering the same number in both the G-code and the offset variable in the settings. I was inadvertantly doubling the offset? SMH

    Sent from my Pixel XL using Tapatalk
     
    mark tomlinson likes this.
  17. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,141
    Likes Received:
    6,998
    Yes, exactly correct. The M565 value is not an absolute number because it is calculated into the level bed calcs. , but whatever G29 calculates it will always include the M565 value. Then if you do a global offset it is added after all that is done.
     
  18. Wesley Knapp

    Wesley Knapp Member

    Joined:
    Jan 19, 2019
    Messages:
    78
    Likes Received:
    32
    Got it figured out, corrected in settings and G-code and it's working perfectly with no more manual adjustments.
    Surely do appreciate the explanations and guidance.

    Sent from my Pixel XL using Tapatalk
     
    Geof and mark tomlinson like this.

Share This Page