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

    Height Map and Leveling Issues + Head Movement

    Scheduled Pinned Locked Moved
    Tuning and tweaking
    7
    40
    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.
    • infiniteloopundefined
      infiniteloop @tdm418
      last edited by

      @tdm418 So, looks like you got two separate problems. As I have no coreXY, you better wait for one of the experts to join this thread. Luckily, most of the most helpful members of this forum seem to have a coreXY sitting on their shelves.

      Talking about Z, your hight map looks rather weird, given that you obviously know what you are doing: after you have levelled the bed carefully, the map should not deviate that much from the bed’s plane.

      Just a guess: Do you move your platform with two or more lead screws? Do you perhaps synchronise these with the help of a belt? If and only if this is true, I can imagine the belts to be the common source of both problems…

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

        can you turn off the bed compensation and see if the movement still surges?

        what can happen is that while moving, it needs to adjust the z position. so it needs to slow down and wait for it to happen.

        1 Reply Last reply Reply Quote 0
        • dc42undefined
          dc42 administrators @tdm418
          last edited by

          The clue to the height map is that RRF probes alternate rows in alternate X directions. So ridges parallel to the X axis indicate that the nozzle height and/or the probe height depend on whether you approach the point from the +X or -X direction.

          The surges you mention are a direct result of the height map. RRF is slowing down motion at the peaks ans troughs of the ridges in order to meet the Z jerk limit when crossing them.

          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

          1 Reply Last reply Reply Quote 0
          • tdm418undefined
            tdm418
            last edited by

            Thanks for all the input.
            @infiniteloop - I have two screws that are not physically connected or synced.
            @Veti - Yes, turning off compensation allows for smooth movement
            @dc42 - So why would this problem suddenly pop up, and what is there to be done about it?

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

              @tdm418 said in Height Map and Leveling Issues + Head Movement:

              So why would this problem suddenly pop up, and what is there to be done about it?

              worn down bearings for example.

              your print head assembly is not rigid enough and allows for roational movement

              1 Reply Last reply Reply Quote 0
              • tdm418undefined
                tdm418
                last edited by

                The printer is only a couple of months old. Everything is still tight and responsive, and I regularly check all my bearings, belt tension, and print head assembly. Also, the problem is surfacing during mesh compensation, which doesn't stress any of the mechanisms or head very much at all.

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

                  Can you post your config.g, bed.g and homing files?

                  How is the BLTouch mounted?

                  Z-Bot CoreXY Build | Thingiverse Profile

                  1 Reply Last reply Reply Quote 0
                  • tdm418undefined
                    tdm418
                    last edited by

                    Here it is:
                    The BLTouch is mounted on a modular printhead design specific to it.
                    It is shimmed with a couple of nuts, but it is rock solid.

                    config.g
                    bed.g
                    homeall.g
                    homey.g
                    homez.g
                    homex.g
                    20191119_173036.jpg

                    1 Reply Last reply Reply Quote 0
                    • fcwiltundefined
                      fcwilt
                      last edited by

                      Hi,

                      Try writing a macro that does a series of G30 S-1 commands

                      That command probes the bed are the current X,Y position and reports the triggered height of the Z probe.

                      It will let you know if the probe is consistent.

                      You can try different X,Y locations and compare the results.

                      Frederick

                      Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

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

                        In homeall.g and bed.g

                        M401 ; deploy probe
                        G30 ; home z0
                        M402 ; retract probe

                        You should remove the M401 and M402. Unnecessary since the firmware will deploy and retract as needed.

                        From config.g

                        M558 P9 H5 F500 T6000

                        Your dive speed is 500mm/min but your maximum Z axis speed is set to 360mm/min. Either way this is higher than the recommended speed of 120mm/min. I don't think this explains your heightmap, but it should help the BLTouch be more consistent.

                        G31 X35 Y0 Z1.202 P5

                        The P value is for trigger sensitivity. For the BLTouch it's recommended to be P25.

                        Z-Bot CoreXY Build | Thingiverse Profile

                        1 Reply Last reply Reply Quote 0
                        • tdm418undefined
                          tdm418
                          last edited by

                          @fcwilt, there was little consistency moving the probe and testing different areas. There appeared to be good uniformity, as one corner of the bed gave low values, and the other corner gave high values, and all points in between seemed to be pretty linear in their reported values. But overall, from the minimum value to the maximum was over 1mm. This is probably symptomatic of the problem, but I still don't have any idea what the problem is.

                          @Phaedrux, I edited the files as you recommended. Reran mesh compensation and the height map has the same patterns in it. It appears lower relative to the mesh, but not much else has changed.

                          1 Reply Last reply Reply Quote 0
                          • fcwiltundefined
                            fcwilt
                            last edited by

                            Hi,

                            Sorry I wasn't clear.

                            I wasn't expecting different areas of the bed to give the same reading, I was just interested if the probe gave consistent readings when repeated at a given position, regardless of position.

                            Different positions are going to likely yield different readings but any given position should yield consistent readings.

                            Frederick

                            Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

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

                              You can try adding some rest time between probe points to let the bltouch settle.

                              M558 R0.5

                              But that pattern would appear to be mechanical in nature. Backlash.

                              Z-Bot CoreXY Build | Thingiverse Profile

                              1 Reply Last reply Reply Quote 0
                              • infiniteloopundefined
                                infiniteloop
                                last edited by

                                @tdm418 If you height map still shows this „sawtooth“ pattern over X, it might be worth to rethink the clue @dc42 gave you: maybe your X-axis, the print carriage, the head or some part of it has come loose and can tilt a bit? At least, I can’t imagine anything but a mechanical reason…

                                1 Reply Last reply Reply Quote 0
                                • tdm418undefined
                                  tdm418
                                  last edited by

                                  @fcwilt, I do get pretty consistent results in the same location. I was under the impression that the value returned was the z offset to the from the nozzle, or more from Z=0, to the height that the probe triggers at. If that is the case, why shouldn't the value be the same regardless of the probe's location, as that is pretty much a fixed distance?

                                  jens55undefined 1 Reply Last reply Reply Quote 0
                                  • tdm418undefined
                                    tdm418
                                    last edited by

                                    @infiniteloop, I have poked, probed, and prodded every component on this printer and can find nothing loose, slipping, or moving. It seems like the logical and probable cause of my pattern, but I can't find anything at all...

                                    1 Reply Last reply Reply Quote 0
                                    • jens55undefined
                                      jens55 @tdm418
                                      last edited by

                                      @tdm418 said in Height Map and Leveling Issues + Head Movement:
                                      why shouldn't the value be the same regardless of the probe's location, as that is pretty much a fixed distance?

                                      Because the glass isn't flat, the mechanics aren't perfect and there really isn't anything in this world that is a 'fixed distance'. Heck, even continents move!

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

                                        An interesting thought since I also have this kind of a sawtooth pattern ....
                                        If I manually move to a given point on the bed while approaching it from the left, take 10 measurements while staying at that point, then move further right and return, this time approaching the same point from the right and take 10 measurements .... should I see a discrepancy of the second set of numbers compared to the first set?
                                        I think I will run that test and see what happens, should be interesting to see the outcome!
                                        Is there a way to probe the bed that doesn't involve the linear travel and uses a more random pattern ?

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

                                          @fcwilt said in Height Map and Leveling Issues + Head Movement:

                                          Try writing a macro that does a series of G30 S-1 commands

                                          here is a link to the complete m48 macro
                                          https://forum.duet3d.com/topic/6962/m48-measure-z-probe-repeatability-and-print-to-serial-output

                                          please run at different positions

                                          1 Reply Last reply Reply Quote 1
                                          • tdm418undefined
                                            tdm418
                                            last edited by

                                            I am traveling for the next couple of days. I'll try it and let you know when I return.
                                            Thank you

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