Duet3D Logo Duet3D
    • Tags
    • Documentation
    • Order
    • Register
    • Login

    What could cause this heightmap pattern

    Scheduled Pinned Locked Moved
    Tuning and tweaking
    7
    53
    2.0k
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • jens55undefined
      jens55
      last edited by

      Ah, that makes sense when I think about it ...... any other thoughts on the pattern ?

      1 Reply Last reply Reply Quote 0
      • Vetiundefined
        Veti
        last edited by

        it could be bed sag. that the bed is deforming under its own weight.

        1 Reply Last reply Reply Quote 0
        • Alex.crundefined
          Alex.cr
          last edited by

          Do you have any sort of magnetic build plate? I’ve seen something like this when adhesive fails on the edges of a bed covering on of one of my printers.

          Voron2.4/Duet3 SBC+6HC+3HC+1LC+1HCL(x2) - Delta/Duet2 Wifi - CubePro/Duet2 Wifi+Duex5 - Laser/Duet3 Mini5+ - Cel Robox - U̶p̶3̶0̶0̶+/D̶u̶e̶t̶3̶ ̶6̶H̶C̶+̶LC1̶ - F̶T̶-̶5̶/̶D̶u̶e̶t̶2̶ ̶W̶i̶f̶i̶ - S̶o̶l̶i̶d̶o̶o̶d̶l̶e̶

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

            Thank you for your thought but no. It is an aluminum bed plate with a glass sheet on top and a 120V AC bed heater underneath.

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

              Could you post a video of the probing routine? At least a good part of it? I'd like to see what the motion of the printer is like.

              Z-Bot CoreXY Build | Thingiverse Profile

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

                Unfortunately my 5 or so year old cell phone is not up to the task of taking such a video 😞 Heck, even a plain photo turns out fuzzy.

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

                  Is the heightmap accurate? If you print a test file like this twice, once with mesh compensation and again with it deactivated, does it print better with it turned on?

                  bedlevel_nozzle_0.4_200x200-0.3-0.8.stl

                  Z-Bot CoreXY Build | Thingiverse Profile

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

                    The height map is accurate. I have run it a total of 6 times. Twice cold, twice at 90C bed temperature and twice at a reduced resolution of 49 probe points with a cold bed.
                    I then did a matrix subtraction of the two probings in each set to see the difference in readings. They turned out surprisingly consistent.
                    Seeing that the difference between high areas and low areas is around 0.4 mm. it becomes very difficult to print anything without mesh compensation.
                    I will give the stl you attached a try and report back.

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

                      @jens55 said in What could cause this heightmap pattern:

                      it becomes very difficult to print anything without mesh compensation.

                      It is a great feature.

                      Z-Bot CoreXY Build | Thingiverse Profile

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

                        The stl file is non printable. It imports into Cura but without a body. I can't slice it.

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

                          It's thin lines in a pattern. You may need to alter the extrusion width for your first layer, or enabled printing thin walls in cura?

                          Z-Bot CoreXY Build | Thingiverse Profile

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

                            @Phaedrux, I will see what I can do ... I have a 0.8 mm nozzle set up so that may be the problem.

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

                              In that case, try this one.

                              bedlevel_nozzle_0.8_200x200-0.4-1.6.stl

                              Z-Bot CoreXY Build | Thingiverse Profile

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

                                Dang it ... just finished making it printable ....

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

                                  OK, the pattern is 0.4 mm tall and I am printing a 0.4 mm layer.
                                  No compensation - about 1/3 of the print was ok, 1/3 was too high and 1/3 was too low.
                                  WIth compensation - 95 % ok, only a small corner lifted a bit, possibly the second nozzle hitting the print.
                                  Now the test was done in the middle of the bed that is relatively even.
                                  Second test with mesh map active but a 0.2 mm layer height - perfect
                                  Third test with same setup as second test but the model moved from the flat lands to the foothills and mountain range. Gut feeling is that the previous (flat land only) layer was a tad thicker but I have nothing but gut feeling to speak for that and the print was also 100% ok!

                                  I am tickled pink about this result !

                                  Of course this doesn't say anything about why the bed patterns are the way they are.

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

                                    It would be interesting to find the reason for your intial question...

                                    My ideas:

                                    • you use glass, this huge difference is strange. Does your sensor measure the glass or the aluminium underneath: which type is the sensor?
                                    • is the print bed fixed by screws (= do they have play for thermal expansion), is it supported below, is it bent by the screws?
                                    • is the visual check in accordance with the measurement: a hairlineal would be perfect, but a h7 precision steel rod could help also, to check whether the surface is really the same as measured
                                    • a mechanical reason is also possible: hotend at the right or left end could stuck the Z movement and produce wrong measurement at the edges (weight changes the angle of the axis. In the middle it's balanced)
                                    jens55undefined 1 Reply Last reply Reply Quote 0
                                    • jens55undefined
                                      jens55 @JoergS5
                                      last edited by

                                      @JoergS5 said in What could cause this heightmap pattern:

                                      • you use glass, this huge difference is strange. Does your sensor measure the glass or the aluminium underneath: which type is the sensor?

                                      BLTouch so it measures the glass surface.

                                      • is the print bed fixed by screws (= do they have play for thermal expansion), is it supported below, is it bent by the screws?

                                      Weeeelllll, that is a bit of an issue but doesn't explain the map. To answer the question, the normal Creality CR10 setup has 4 spring loaded screws. They are maybe 20 mm long so there is a built-in compliance. I have removed the spring, installed a locking nut underneath the bed and two nuts around the lower support - one below and one above. This does introduce some issues with stress but since the screws are fairly long, I am assuming/homing that there is enough give. If there wasn't enough give I would expect some deformation around those 4 screws but what I am seeing is completely different.

                                      • is the visual check in accordance with the measurement: a hairlineal would be perfect, but a h7 precision steel rod could help also, to check whether the surface is really the same as measured

                                      Not sure what you are saying here but multiple probings ot he entire bed were done and they were confirmed to be fairly close.

                                      • a mechanical reason is also possible: hotend at the right or left end could stuck the Z movement and produce wrong measurement at the edges (weight changes the angle of the axis. In the middle it's balanced)

                                      Not sure about this question either but off hand there is nothing that I see in the bed map that I could contribute to a slight angle change.

                                      JoergS5undefined 2 Replies Last reply Reply Quote 0
                                      • 4latheundefined
                                        4lathe
                                        last edited by

                                        What side of the bed does the wire bundle/filament come from into the carriage? High X maybe?

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

                                          @4lathe left side

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

                                            @jens55 Let me clarify what I meant with points 3 and 4:

                                            Visual check: I meant you can check visually with a precision tool whether it is really your print bed which has this form or the gantry or other error A hairlineal allows to see unevenness, but if you don't have one you could use something other very even. The goal is to decide where the problem can be.

                                            Mechanical reason: I mean that your printer has two actuators to move Z, so there is a possibility that the two hinder each other moving. One possibility is that they get stuck at the sides. You can test it by temporarily more mass load on the hotend, so effects like backlash or angled axis will show in the meshmap (becoming better or worse). The mass should not be so high that the steppers don't move any more but high enough (maybe 1 kg). More differences => stuck of the movement, less differences => backlash effect.

                                            1 Reply Last reply Reply Quote 0
                                            • First post
                                              Last post
                                            Unless otherwise noted, all forum content is licensed under CC-BY-SA