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    Problems with input shaping

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    Tuning and tweaking
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    • tasundefined
      tas @Lee
      last edited by

      @Lee I finally got my Ender 5 Plus back up and running today with new E3D 0.9 degree stepper motors (trying to get rid of my VFAs!). I will have to do a full recalibration so I will do some Input Shaping tests and see if I can come up with something of help to you.

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      • tasundefined
        tas
        last edited by

        @Lee I did some tests.

        I now have the E3D 0.9 degree motors for X and Y. This has changed a lot for me so I have to do a full recalibration of the printer. For these tests I used my original values though and enabled only input shaping using my new center frequency of 39 Hz. So Acceleration of 1400 and Jerk max of 900. M593 P"EI3" F39.0 S0.0.

        I used PrusaSlicer 2.6.0 with the following custom g-code in Printer Settings>After Layer Change G-Code:

        ;Try Input Shapers
        {if layer_z >= 0.2}M593 P"none"{endif}
        {if layer_z >= 5.0}M593 P"mzv" F39 S0.0{endif}
        {if layer_z >= 10.0}M593 P"zvd" F39 S0.0{endif}
        {if layer_z >= 15.0}M593 P"zvdd" F39 S0.0{endif}
        {if layer_z >= 20.0}M593 P"zvddd" F39 S0.0{endif}
        {if layer_z >= 25.0}M593 P"ei2" F39 S0.0{endif}
        {if layer_z >= 30.0}M593 P"ei3" F39 S0.0{endif}

        Using the Klipper Ringing_Tower.stl as you did the above code chooses another Input Shaper at each new scallop.

        So first sample, Acceleration 1400, Jerk 900, speed 50mm/s, no PA. I apologize in advance for my photography. Not great.

        Jerk 900, acc 1400 spd 50mms-2.JPG

        There is a slight difference at each corner for the different input shapers. This does not show up in my photos. For some shapers the start side of the corner looks better, for others the end side. For 'none' there is prolonged ringing and varying (but much less ringing) for the input shapers.

        For the second sample I changed Jerk to 100 from 900. On the last three scallops at the top I doubled the speed to 100mm/s. A shallow wave appeared at that speed. Jerk gives worse ringing at 100 with no input shaper because the 1400 acceleration worked best with 900 jerk (and my old motors). However the lower jerk looks much better with input shaping. There is definitely less ringing.

        Jerk 100, acc 1400 spd 50mms and 100mms.JPG .

        You should definitely see a difference with input shaping enabled.

        Leeundefined 1 Reply Last reply Reply Quote 0
        • gloomyandyundefined
          gloomyandy @Lee
          last edited by

          @Lee As others have said the resonance frequency you are targeting (19.5Hz in the above is very low) and my understanding is that input shaping does not work well below approx 25Hz. This is a comment from the Klipper documentation:

          Another consideration is that if a resonance frequency is too low (below 20-25 Hz), it might be a good idea to increase the printer stiffness or reduce the moving mass. Otherwise, acceleration and printing speed may be limited due too much smoothing now instead of ringing.
          
          Leeundefined 1 Reply Last reply Reply Quote 0
          • Leeundefined
            Lee @gloomyandy
            last edited by

            @gloomyandy but what frequency should i use than? No matter what I do the results are almost identical every time

            jay_s_ukundefined gloomyandyundefined 2 Replies Last reply Reply Quote 0
            • Leeundefined
              Lee @tas
              last edited by

              @tas I also have the e3d 0.9 degree motor i will try printing with the g code modifiers you used

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              • jay_s_ukundefined
                jay_s_uk @Lee
                last edited by

                @Lee can you show how you are mounting the accelerometer?

                Owns various duet boards and is the main wiki maintainer for the Teamgloomy LPC/STM32 port of RRF. Assume I'm running whatever the latest beta/stable build is

                Leeundefined 1 Reply Last reply Reply Quote 0
                • Leeundefined
                  Lee @jay_s_uk
                  last edited by

                  @jay_s_uk There us a picture above it is mounted at the back of the tool head

                  jay_s_ukundefined 1 Reply Last reply Reply Quote 0
                  • jay_s_ukundefined
                    jay_s_uk @Lee
                    last edited by

                    @Lee you may need to improve the mounting to make it more fixed

                    Owns various duet boards and is the main wiki maintainer for the Teamgloomy LPC/STM32 port of RRF. Assume I'm running whatever the latest beta/stable build is

                    Leeundefined 1 Reply Last reply Reply Quote 0
                    • Leeundefined
                      Lee @jay_s_uk
                      last edited by

                      @jay_s_uk I will try tighteing the screw that holding the accelerometer.

                      jay_s_ukundefined 1 Reply Last reply Reply Quote 0
                      • jay_s_ukundefined
                        jay_s_uk @Lee
                        last edited by

                        @Lee you probably need more than just 1 screw

                        Owns various duet boards and is the main wiki maintainer for the Teamgloomy LPC/STM32 port of RRF. Assume I'm running whatever the latest beta/stable build is

                        Leeundefined 1 Reply Last reply Reply Quote 0
                        • Leeundefined
                          Lee @jay_s_uk
                          last edited by

                          @jay_s_uk ok than i will design a new holder

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                          • gloomyandyundefined
                            gloomyandy @Lee
                            last edited by

                            @Lee Looking at the test print you did I'm not actually seeing much ringing on it at all (you may be able to see more than we can in a photo). If you can see ringing on the print I'd ignore the accelerometer and just use the manual way of estimating the frequency by measuring the peaks of the ringing, see: https://www.klipper3d.org/Resonance_Compensation.html

                            Leeundefined 2 Replies Last reply Reply Quote 0
                            • Leeundefined
                              Lee @gloomyandy
                              last edited by

                              @gloomyandy I think manually turning it may be my best option becasue i dont think it a mounting issue

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                              • Leeundefined
                                Lee @gloomyandy
                                last edited by Lee

                                @gloomyandy I am now confused as heck. I have tried the manual tuning around 15 times and none of my test were consistent, and the last one was the one that confused me the most. I had both input shaping and pressure advanced off. And it had next to no ringing. But the test before that with the exact same settings and gcode had a hell of a lot of ringing. WTF is going on?

                                And the frequencies I calculated are all around 34 Hz and from what I heard here that seems to low

                                I am running a direct drive extruder, which makes the tool head heavier but dose more weight lead to lower frequency?

                                tasundefined 1 Reply Last reply Reply Quote 0
                                • tasundefined
                                  tas @Lee
                                  last edited by

                                  @Lee Being confused is a part of 3D printing in my experience.

                                  34 Hz is not too low.

                                  The extruder on my Ender 5+ (heavily modified, I call it Printenstein) is heavy. It is an original Hermes (Hemera) direct drive extruder with Volcano block and two 2015 fans. I made a custom backing plate to mount it to the Creality carriage.

                                  It gets roughly the same frequencies as my Ender 5 Pro (heavily modified also) which has a relatively light weight E3D V6 with LGX lite direct drive extruder.

                                  If you are not getting consistent results maybe go over everything and check for loose bolts. Sorry I can't be of more help.

                                  Leeundefined 1 Reply Last reply Reply Quote 0
                                  • Leeundefined
                                    Lee @tas
                                    last edited by

                                    @tas I will check all the bolts again and tighten my belts up even more again and try to run something other than the ringing test, but thanks for your help anyway.

                                    tasundefined 1 Reply Last reply Reply Quote 0
                                    • tasundefined
                                      tas @Lee
                                      last edited by

                                      @Lee No Problem. I find it helpful to disconnect the motors and move all axes to look for stiff spots/bad bearings. That can be very difficult to detect with motors still connected.

                                      Good luck.

                                      Leeundefined 1 Reply Last reply Reply Quote 0
                                      • Leeundefined
                                        Lee @tas
                                        last edited by

                                        @tas Thanks for the tip, I will definitely try that. I just finished running a test which looks promising. What I ended up doing was taking an average of the frequencies I calculated and used that as my shaper frequency and I think it looks good.

                                        This was Printed at 100 mm/s.
                                        IMG_2445.jpeg

                                        tasundefined 1 Reply Last reply Reply Quote 0
                                        • tasundefined
                                          tas @Lee
                                          last edited by

                                          @Lee Much better.

                                          If you pick EI3 as the shaper just to try it I believe it covers the widest frequency band. So hopefully even if you don't get the frequency exactly right it will still be ok.

                                          Once you get it working make sure to print some actual parts to see if there are issues with corners etc.

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