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    Strange Ringing artifacts on coreXY

    Scheduled Pinned Locked Moved
    Duet Hardware and wiring
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    • deckingmanundefined
      deckingman @Neoxio
      last edited by

      @neoxio said in Strange Ringing artifacts on coreXY:

      Do you have quality 3M belts or china? How about your hotend mount is it stable or wobbly.

      Check his OP - seems he's tried them.

      Ian
      https://somei3deas.wordpress.com/
      https://www.youtube.com/@deckingman

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      • Phaedruxundefined
        Phaedrux Moderator
        last edited by Phaedrux

        I had very similar ridges on my corexy and the solution for me was to replace the toothed idlers with smooth bearings and do a belt flip so the smooth side rode on the bearings. It seemed that the diameter of the idler was too small or the profile of tooth and belt mismatched enough that it wasn't meshing smoothly.

        Also, I recall a thread from not long ago where using very low steps per mm was causing motor movement to be less smooth.

        Just some thoughts

        alt text

        Here's an example of what I had.

        Z-Bot CoreXY Build | Thingiverse Profile

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        • whosrdaddyundefined
          whosrdaddy
          last edited by

          Could be an extrusion problem.
          Add some pictures of the complete printer so we can have a better idea...

          mrehorstdmdundefined 1 Reply Last reply Reply Quote 0
          • mrehorstdmdundefined
            mrehorstdmd @whosrdaddy
            last edited by mrehorstdmd

            @whosrdaddy

            I second the vote for extrusion problem. Try changing the extruder motor current up or down 20% and see if the pattern changes.

            I've seen this in direct extruders with no gear reduction and relatively large filament drive gears.

            What kind of extruder is on the machine?

            https://drmrehorst.blogspot.com/

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            • makerdiseundefined
              makerdise
              last edited by makerdise

              @whosrdaddy @mrehorstdmd @kuhnikuehnast did test a bowden setup as an alternative, while currently running a zesty nimble (which sounds like a hot candidate having a non concentric part or imprecise worm drive etc.)... This was also one of my first ideas (inconsistent extrusion). However, the pattern remains nearly the same on both setups. The distance between the "waves" is very consistent so this could only be caused by a part moving around in circles with a non-concentric bore or wrong clamping (in theory).

              Damn.

              @mrehorstdmd - are you the guy with the belt driven z-axis printer, do I remember right? If so, respect.

              The biggest european Duet3D reseller
              https://www.makerdise.com

              mrehorstdmdundefined 1 Reply Last reply Reply Quote 0
              • kuhnikuehnastundefined
                kuhnikuehnast
                last edited by

                as @makerdise already told: at first, I was "hoping" to have an extrusion problem... But as I tried 2 different types of extruders and also with 2 different stepper motors, the problem persisted. And if you watch the video, you can also se the "sine wave like" spinning on the axis. These videos were made by just "printing" a g-code like:

                G21
                G91
                M564 S0 H0
                G0 X300 F6000
                G0 X-300 F6000
                G0 X300 F6000
                G0 X-300 F6000
                ...

                So all the possible interfering factors were eliminated.

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                • Neoxioundefined
                  Neoxio
                  last edited by

                  Does it get worst when u print @ 0.1mm layer hight? (does the "ringing" changes, increase?)

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                  • T3P3Tonyundefined
                    T3P3Tony administrators
                    last edited by T3P3Tony

                    @kuhnikuehnast, @makerdise It looks like you have carried out a detailed investigation so far. To try and isolate the problem to a subsytem (electronics/mechanical) can you try changing:

                    1. Movement axis interpolation this line in config.g "M350 X16 Y16 Z16 E16 I1 " change so that X and Y are not using interpolation:
                      M350 Z16 E16 I1
                      M350 X16 Y16 I0

                    2. As a seperate test, try different microstepping for movement axis:
                      "M350 X64 Y64 Z16 E16 I1 "
                      You may need to reduce the print speed. Also make sure you follow the documentation about how the microstepping and steps/mm interact. https://duet3d.dozuki.com/Wiki/Gcode#Section_M350_Set_microstepping_mode

                    www.duet3d.com

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                    • whosrdaddyundefined
                      whosrdaddy
                      last edited by

                      I had a look at the videos, it seems that X axis has issues (20 micron range is a lot).
                      Could be something simple as binding or a bad bearing.

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                      • kuhnikuehnastundefined
                        kuhnikuehnast
                        last edited by

                        Would be great if it was that simple... As I only wanted to use high quality parts I installed Misumi long bearings...😐 Bending isn't a probleme I think.

                        Steppings:
                        Already tried switching off interpolation and tried from full step to 1/32. But I will give a second try later (just out for dinner)

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                        • makerdiseundefined
                          makerdise
                          last edited by makerdise

                          @kuhnikuehnast - I am unsure if we did test the M350 X16 Y16 while setting the I flag to 0 explicit...

                          @T3P3Tony - for sure we did test a lot and discussed a bunch of common and uncommon things. It seems to be more complex in this case. I was focused on the mechanical subsystem since we did some tests today. As written in the OP, the belts, pulleys were changed, so they are out. We measured the rods, the movement was ~0.05mm. There's no measurable bending or movement of the frame. So we continued debugging within the XY frame, by measuring if the Y carriages does bend in x direction while moving x, and they didn't. The only measurable movement within a linear x move(as seen in the video) is into the y direction (+-0.2mm = 0.4mm). You can clearly see this sinus wave like pattern with a ball pen mounted on the x carriage painting on paper. In conclusion, we have to find all factors that can cause kind of a stuttering in the motors. As the motors were changed, it can be related to soft- or hardware issues.

                          I thought about an issue with M669 which was introduced in RRFW 1.1.9 - are there potential collisions with M667 or known issues related to CoreXY?

                          Maybe @dc42 can join the discussion to bring in some light into the darkness 😉

                          The biggest european Duet3D reseller
                          https://www.makerdise.com

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                          • mrehorstdmdundefined
                            mrehorstdmd @makerdise
                            last edited by

                            @makerdise

                            Yeah, I have the belt lifted Z axis. I recently put a Volcano and 0.8 mm nozzle back on it to print some structural parts and ran into some Z axis banding problems that I am starting to think are due to the gears in the worm drive that lifts the Z axis. I'll probably do a post on it to see what other think is going on.

                            Older prints made with a standard heater block and 0.4 mm nozzle in 0.2 mm layers don't seem to have the problem, or have it to a much lesser, more acceptable extent.

                            I have a CubexDuo with a relatively large diameter filament drive gear that produces little ridges in the walls of prints and seems to be related to the microstepping causing the motor to pulse enough to create the ridges. For some reason, changing the motor current changes the spacing/angle of the ridges.

                            https://drmrehorst.blogspot.com/

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                            • makerdiseundefined
                              makerdise
                              last edited by

                              @mrehorstdmd - this is a real nice project. I like the worm drive, in my research I only found a very few ideas to stop the unwanted z movement and this is the best implementation.

                              OMG, another complex issue 🙂 😉 For sure, feel free to post it by pm or here. Did you thought about a PID related issue? Is it possible that the block itself is bending cause of this and the vertical alignment? Did you ever tune the PID's after changing the block? Are you using the volcano sock?

                              Do you have any detailed information on the motor pulsing, this seems to be interesting...

                              The biggest european Duet3D reseller
                              https://www.makerdise.com

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                              • whosrdaddyundefined
                                whosrdaddy
                                last edited by

                                Question, what firmware are you currently using?

                                1 Reply Last reply Reply Quote 0
                                • mrehorstdmdundefined
                                  mrehorstdmd @makerdise
                                  last edited by

                                  @makerdise

                                  The machine still has the smoothieboard in it, so I'll post here after I get it switched to the Duet if the problem persists. I was preparing to install the Duet and got side-tracked by the print quality problems that suddenly appeared when I switched to 1) volcano and 0.8 mm nozzle, 2) 0.4 mm layers, and 3) white ABS.

                                  I'm hoping it isn't the worm drive...

                                  https://drmrehorst.blogspot.com/

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                                  • kuhnikuehnastundefined
                                    kuhnikuehnast
                                    last edited by

                                    Do not cap my thread 😜

                                    But back to topic:
                                    Here a picture of my printer:
                                    0_1526420009376_20180515_231101 (Large).jpg

                                    And here the 2 tests:
                                    on the left:
                                    M350 Z16 E16 I1
                                    M350 X16 Y16 I0

                                    on the right:
                                    M350 X64 Y64 Z16 E16 I1

                                    Both look pretty identical... 😞
                                    0_1526420058702_20180515_232835 (Large).jpg

                                    The 0.1 mm layer height is still printing.

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                                    • makerdiseundefined
                                      makerdise
                                      last edited by

                                      @kuhnikuehnast will arrange a test with unmounted motors and a flag on my recommendation...

                                      The biggest european Duet3D reseller
                                      https://www.makerdise.com

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                                      • hurzhurzundefined
                                        hurzhurz
                                        last edited by

                                        @kuhnikuehnast I had the same problem on my HEVO.
                                        You may have a look at this thread:
                                        https://forum.duet3d.com/topic/4246/vertical-banding

                                        There is mentioned that the problem probably lies in a to small current and especially to few steps per mm.

                                        I had 1.8° steppers with a maximum rated current of 1.2A from an aliexpress hevo kit.
                                        Because of the thread, I then switched to these 0.9° 1.7A steppers:
                                        https://www.think3dprint3d.com/motors?product_id=122

                                        That helped a lot and practically solved the problem for me!

                                        I drive them with 1.2A, 16x microstepping and 160steps/mm.

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                                        • dc42undefined
                                          dc42 administrators
                                          last edited by

                                          What is the pitch of the banding, and how many motor full steps and pulley teeth does it correspond to?

                                          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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                                          • kuhnikuehnastundefined
                                            kuhnikuehnast
                                            last edited by

                                            @dc42 The pitch seems to be 2 mm (full "sine wave") which corresponds to 1 tooth (GT2-Belts).
                                            as I am using 1.8° motors :

                                            • 80 steps per mm at 1/16 microstepping
                                            • so 5 steps per mm at fullstep
                                            • 2 mm banding--> 10 full steps.

                                            I yesterday did another test:
                                            disconnetcted the stepper motors and connected the spools with jumper wire. (to produce a good holding torque). then I carefully tried to move the x-axis back and forward only using one finger and measured the maximum distance with a gauge-> this is +/- 0,1 mm, so 0,2 mm in total. And exactly the movement shown in the videos I posted...

                                            dc42undefined 1 Reply Last reply Reply Quote 0
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