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    Laser filament monitor

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    Filament Monitor
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    • dc42undefined
      dc42 administrators
      last edited by

      @bot:

      Oh, interesting. Is there a possibility that focus or intensity needs to be adjusted? Perhaps even for each different filament colour?

      There is no focus or power adjustment, although the reflected intensity can be read. We might be able to use that to increase the tolerance automatically when the reflected intensity is low.

      @bot:

      Perhaps the laser monitor could read a pattern on the circumference of a hobbed wheel that is idling against the filament – or perhaps even just the grain of the metal of the hobbed wheel would track better than the surface of filament.

      If we did that, we would lose the benefit of mechanical simplicity of this design over the previous rotating magnet design.

      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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      • botundefined
        bot
        last edited by

        @dc42:

        @bot:

        Perhaps the laser monitor could read a pattern on the circumference of a hobbed wheel that is idling against the filament – or perhaps even just the grain of the metal of the hobbed wheel would track better than the surface of filament.

        If we did that, we would lose the benefit of mechanical simplicity of this design over the previous rotating magnet design.

        Yes, that's true.

        How was the accuracy of the magnet based sensor? I would be willing to forgo a bit of simplicity if the accuracy was dramatically improved.

        *not actually a robot

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        • DjDemonDundefined
          DjDemonD
          last edited by

          I thought the basic idea was sound, the hobbled wheel gripped the filament and turned reliably, it was the variable nature of the 3d printed casings holding it all together, which allowed the magnet attached to the hobbed shaft, to move away from the sensor chip that let it down, and I've a pretty accurate printer to make them with. An injection moulded or machined casing would have made a big difference and dropping monitoring of retractions, but it was still a clunky solution compared to a tiny pcb which could easily be built into an extruder if it works better.

          Simon. Precision Piezo Z-Probe Technology
          www.precisionpiezo.co.uk
          PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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          • dc42undefined
            dc42 administrators
            last edited by

            I found the accuracy of the magnet based sensor was around 20% after calibration. It is limited by the need to use a low data rate to the Duet (1000bps) because of the filtering capacitors in the Duet endstop circuits.

            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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            • JohnOCFIIundefined
              JohnOCFII
              last edited by

              @dc42:

              @bot:

              Is there an LED illuminating the filament for the sensor?

              Not an LED, a tiny diode laser.

              I took @bot's question to be a suggestion that perhaps the addition of a tiny LED to the PCB might supply additional light that would (perhaps) assist with the sensing.

              (Out of my league here - but if by chance that is a useful suggestion - just wanted to call it out).

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              • botundefined
                bot
                last edited by

                @JohnOCFII:

                @dc42:

                @bot:

                Is there an LED illuminating the filament for the sensor?

                Not an LED, a tiny diode laser.

                I took @bot's question to be a suggestion that perhaps the addition of a tiny LED to the PCB might supply additional light that would (perhaps) assist with the sensing.

                (Out of my league here - but if my chance that is a useful suggestion - just wanted to call it out).

                Oh, I wasn't really suggesting anything, just asking out of curiousity – I forgot that it was called a "laser" filament monitor.

                *not actually a robot

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                • dc42undefined
                  dc42 administrators
                  last edited by

                  Not a production line yet, but a start.

                  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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                  • S1lencerundefined
                    S1lencer
                    last edited by

                    Looks nice,
                    what are the production costs for such a small batch?

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                    • dc42undefined
                      dc42 administrators
                      last edited by

                      @S1lencer:

                      Looks nice,
                      what are the production costs for such a small batch?

                      I assembled them by hand. So if I charged my normal consultancy rate for assembling them, the production costs would be very high!

                      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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                      • deckingmanundefined
                        deckingman
                        last edited by

                        I see 5 in the Pic. Just the number that I'd need for my 5 colour printer. 🙂

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

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                        • Iiraiundefined
                          Iirai
                          last edited by

                          Can't wait till these are done! Tired of large prints failing due to filament errors…

                          Computer Engineering Student
                          Duet Wifi Delta 560mm W x 1000mm H; ; Print area 400mm circle by 300-360mm height

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                          • Dougal1957undefined
                            Dougal1957
                            last edited by

                            Yeas also waiting on them to hit production so that I can install one this would be much easier to fit with the Nimble than the rotary one?

                            Doug

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                            • RGN01undefined
                              RGN01
                              last edited by

                              Me too - after I found that my old own-design ones are not compatible with the Duet. These look a great alternative!

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                              • dansker61undefined
                                dansker61
                                last edited by

                                Hi, I'm new here 😉

                                I have a Duet Ethernet and accessories ready to be installed, but am still working on a new printer in which to use it, so no actual experience yet with this no doubt amazing controller.

                                I will definitely want to install a filament monitor, and the laser option seems like a very elegant approach. I already have a simple switch installed at the far end of the tube, to set off an alarm in case the filament runs out, and another closer to the extruder that stops the print if no new filament has been loaded. However, stop of movement due to a blocked nozzle is a bigger concern.

                                My reason for this post is a question related to complexity of the filament monitor; What is the added value of monitoring retraction and re-priming?

                                Both are fast-moving actions and unlikely to cause a blockage. If there is a stop of movement, I believe it would have happened already during normal feeding of the filament. I find it highly unlikely that retract/re-prime will trigger an alarm before normal movement and, even if it does, normal movement alarm will immediately follow. Am I overlooking something?

                                Another question; I would like to keep my simple switch as it is easier for me to resupply filament before it hits the extruder. Can a simple switch work in parallel with the filament monitor on a single end-stop port?

                                Thank you for all of your hard work. It is not the cheapest solution, but one that is extremely well supported and that makes all the difference.

                                Michael

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                                • dc42undefined
                                  dc42 administrators
                                  last edited by

                                  Hi @dansker61, welcome to the forum.

                                  I agree with you, as long as the retraction speed and acceleration have been set to values that the extruder can manage, I don't think it should be necessary to monitor retractions and re-prime moves.

                                  Both filament monitor designs have an option to connect a switch to monitor presence of filament. The switch should be closed when filament is present.

                                  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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                                  • dansker61undefined
                                    dansker61
                                    last edited by

                                    I'm wondering if detection can be improved by adding a reflector on one or both sides of the filament channel?

                                    You surely do not want the laser to reflect on itself, but the beam is hitting a curvature (round filament) and that means reflection to the sides. Maybe it would help to pick up those reflections and send them back. Thin stripes of aluminum foil might do.

                                    Quick pencil drawing…
                                    Reflectors

                                    Not sure why the image doesn't load, but the link works also

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                                    • deckingmanundefined
                                      deckingman
                                      last edited by

                                      I'm sure that the prototypes will be subjected to rigorous testing, so if detection needs to be improved the necessary steps will be taken.

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

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                                      • idaho creatorundefined
                                        idaho creator
                                        last edited by

                                        I like the simplistic idea of the laser. I have one of the magnetic sensors and had to take it off because it drove me nuts when the magnet would slide away from the sensor. Although when it work properly it worked well. Its going on my delta as soon as I finish it.

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                                        • BikingVikingundefined
                                          BikingViking
                                          last edited by

                                          Hi folks, very interested in this when/if it reaches production. I was just wondering though about the possibility of using some sort of ultrasonic sensor which could detect density and hence be more accurate?

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                                          • dc42undefined
                                            dc42 administrators
                                            last edited by

                                            I don't think you could detect filament motion using ultrasound because the filament surface s too smooth. Also you would need to use high frequency ultrasound to get the wavelength shorter than the filament diameter.

                                            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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