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    What could cause this heightmap pattern

    Scheduled Pinned Locked Moved
    Tuning and tweaking
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    • jens55undefined
      jens55 @dc42
      last edited by

      @dc42 , B1 is turned on

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      • jens55undefined
        jens55 @4lathe
        last edited by

        @4lathe , I am aware of the 3 point thing but the bed is supported at three points so I decided to keep that going to the glass plate.
        No on the binding wire loom.

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        • dc42undefined
          dc42 administrators
          last edited by

          Where you have the ridges and valleys in the Y direction towards the right hand end of that height map, I would be interested to see what it looks like if you probe that part of the bed with a smaller X spacing.

          Duet WiFi hardware designer and firmware engineer
          Please do not ask me for Duet support via PM or email, use the forum
          http://www.escher3d.com, https://miscsolutions.wordpress.com

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          • jens55undefined
            jens55
            last edited by

            I just started a 9 hr print but I will run a mesh probe tomorrow as per request.

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            • jens55undefined
              jens55
              last edited by

              Interesting pattern ....! Just not sure what it tells me.

              Screenshot from 2019-12-12 17-23-15.png

              dc42undefined 1 Reply Last reply Reply Quote 0
              • dc42undefined
                dc42 administrators @jens55
                last edited by

                Interesting indeed! Did you try rotating the bed 90 degrees?

                Duet WiFi hardware designer and firmware engineer
                Please do not ask me for Duet support via PM or email, use the forum
                http://www.escher3d.com, https://miscsolutions.wordpress.com

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                • jens55undefined
                  jens55
                  last edited by

                  It is a CR10S-5 .... whoa .... the original post vanished 🙂
                  Anyway, aluminum v rails, aluminum bed, glass plate on bed.
                  Ha .. a new question appears 🙂
                  Yes, tried rotating, no difference.

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                  • JoergS5undefined
                    JoergS5
                    last edited by

                    I still think your Z axis is stuck due to different movements of left and right. I would put 0.5 kg additional weight on the hotend temporarily and measure again. This will show you the problem, because it will make it worse or better.

                    jens55undefined 1 Reply Last reply Reply Quote 0
                    • jens55undefined
                      jens55
                      last edited by

                      I will see if there is a way of adding some weight to explore that possibility.

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                      • 4latheundefined
                        4lathe
                        last edited by

                        To joergs5’s point, can you probe the bed from a different direction in any way than you have been? As in always from the right or in the opposite direction in each row from what you have been been doing. That
                        might answer the question of whether loading from one side or the other is creating the ridges and troughs.

                        jens55undefined 1 Reply Last reply Reply Quote 0
                        • jens55undefined
                          jens55 @4lathe
                          last edited by

                          @4lathe , the printer uses the standard Duet probing method starting at the front left, going to the front right, doing one step over (depending on probing density), starting on the right and probing to the left.
                          In other words the probing happens from both sides and no difference is seen in the bed pattern.
                          The pattern is seen in the Y direction and short of coding a completely manual scan, I have no idea how to tell Duet to scan 'backwards'.

                          Phaedruxundefined 1 Reply Last reply Reply Quote 0
                          • Phaedruxundefined
                            Phaedrux Moderator @jens55
                            last edited by

                            @jens55 said in What could cause this heightmap pattern:

                            I have no idea how to tell Duet to scan 'backwards'.

                            I guess you could swap your coordinate system to make the rear right corner 0,0

                            Z-Bot CoreXY Build | Thingiverse Profile

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                            • 4latheundefined
                              4lathe
                              last edited by

                              Great idea Phaedrux. When the probes happen from the opposite direction, if there is indeed a loading or stacking issue, shouldn't the valleys and ridges on the map be reversed?

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                              • jens55undefined
                                jens55 @JoergS5
                                last edited by

                                @JoergS5 said in What could cause this heightmap pattern:

                                I still think your Z axis is stuck due to different movements of left and right. I would put 0.5 kg additional weight on the hotend temporarily and measure again. This will show you the problem, because it will make it worse or better.

                                Well it's not happening. I added a 600 gr chunk of lead and it promptly got loose . I only lost my BLTouch mount (thank God) in the process. I am not going to risk the glass plate.

                                JoergS5undefined 1 Reply Last reply Reply Quote 0
                                • JoergS5undefined
                                  JoergS5 @jens55
                                  last edited by JoergS5

                                  @jens55 Sorry to hear that! I hope, it's not too much damaged.

                                  The test was intended for:
                                  a) if it gets worse, this may be due to stuck axis because of the difference between the two vertical aluminium extensions are too narrow or too wide. Can you test this manually?
                                  b) if it gets better, the reason may be that you have backlash effects. This means, if Z changes, the movement changes the position at your left and right spindle with play. Alternatively, the connector between stepper and spindle is flexible too, it has backlash also. I don't know a different possibility than to make the hotend heavier to find it out without disassambling and replacing the connector.

                                  c) is possible also, as David suggested, that measuting by BLtouch has a problem

                                  In your last screenshot the left side was lower than the right. You can move the left stepper isolated so that the distance of left and right are smaller (lift left side for about 0.25 mm) like described in https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors

                                  jens55undefined 1 Reply Last reply Reply Quote 0
                                  • jens55undefined
                                    jens55 @JoergS5
                                    last edited by

                                    @JoergS5 said in What could cause this heightmap pattern:

                                    @jens55 Sorry to hear that! I hope, it's not too much damaged.

                                    The test was intended for:
                                    a) if it gets worse, this may be due to stuck axis because of the difference between the two vertical aluminium extensions are too narrow or too wide. Can you test this manually?

                                    I do not understand what you are trying to say.

                                    b) if it gets better, the reason may be that you have backlash effects. This means, if Z changes, the movement changes the position at your left and right spindle with play. Alternatively, the connector between stepper and spindle is flexible too, it has backlash also. I don't know a different possibility than to make the hotend heavier to find it out without disassambling and replacing the connector.

                                    I do not understand why backlash would only show up at a particular x coordinate.

                                    c) is possible also, as David suggested, that measuting by BLtouch has a problem

                                    Unlikely as the issue is very specific. A measuring defect would show random errors.

                                    In your last screenshot the left side was lower than the right. You can move the left stepper isolated so that the distance of left and right are smaller (lift left side for about 0.25 mm) like described in https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors

                                    Before any mesh map is run, I already do a Z axis equalization (actually 5 times). Z is within 0.005 for the ends of x travel for the given y location where the measurement is happening.

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                                    • JoergS5undefined
                                      JoergS5 @jens55
                                      last edited by

                                      @jens55 it's complicated to explain better... Sorry. The backlash could show up at particular coordinates, because some micrometer differences between the vertical axis resulting in different resistance and movement.

                                      The article https://all3dp.com/2/best-creality-cr-10-s5-upgrades-and-mods/ talks about some issues in chapter "Better bed mounting", maybe this helps.

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                                      • JoergS5undefined
                                        JoergS5 @jens55
                                        last edited by

                                        @jens55 On reddit are two articles about the Z axis connector between stepper and spindle:
                                        https://www.reddit.com/r/CR10/comments/9epw4u/didnt_want_to_do_this_butwtf_zaxis_cr10s/
                                        https://www.reddit.com/r/CR10/comments/9mpsl1/cr10_with_dualzaxis_option_unable_to_level_xaxis/
                                        which talk about how to fix this.

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                                        • JoergS5undefined
                                          JoergS5
                                          last edited by

                                          The two reddit articles are both interesting. The out of sync of the two Z steppers is a general problem of all those printers: when you turn off the printer, they are often not synched any more, because the position of the full steps can change (up to 4 steps difference!).
                                          The other possible reason mentioned are vertical aluminium axes which are not exactly parallel.
                                          The third are the connectors between stepper and spindle.

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                                          • JoergS5undefined
                                            JoergS5
                                            last edited by JoergS5

                                            One more hint is in https://www.cnx-software.com/2017/05/05/creality-cr-10-3d-printer-review-part-2-tips-tricks-octoprint-and-craftware/
                                            "Sure enough z axis rod was in a bind. I didn’t even realize this. But one symptom is that before this I was only able to push the z axis down. Now I am mostly able to move up and down with the stepper motors disabled." adding a washer between Z stepper and axis.
                                            (maybe different printer than yours)

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