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    Why not brushless motors in direct drive extruders?

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    • Catalin_ROundefined
      Catalin_RO @zapta
      last edited by

      @zapta Extruding is all about torque at relative low RPM. This is what I see for those really interesting solutions:

      • Maximum torque 1.99Nm or 3.86Nm, but that comes with a peak current of no less than 65A!!!
      • A big note - "*Note that torque and current ratings are with Extremely good forced air cooling"
      • RPM at no load - 5760RPM or 8640RPM.

      The torque I get, at much lower speeds of course, from a rather standard NEMA 23 at 2.4A and no need for extra cooling.

      And the pricing... the driver is a merely 179EUR. You get 3 or even 4 decent Leadshine drivers for that amount!

      Again, that is exactly what I have stated... it is a solution, bot not for extruding the filament! I would see it more likely for the gantry movement where, in a 3D printer, the required torque is very low but the speed is high. But, still, it might not justify the extra costs...

      zaptaundefined 2 Replies Last reply Reply Quote 0
      • Catalin_ROundefined
        Catalin_RO @rjenkinsgb
        last edited by

        @rjenkinsgb said in Why not brushless motors in direct drive extruders?:

        They both use permanent magnet rotors and wound stators.
        (Steppers do not have plain iron cores - if you turn one, you can feel the rotor magnet jumping from alignment with one stator pole to the next).

        Unless they are variable reluctance ones!

        rjenkinsgbundefined 1 Reply Last reply Reply Quote 0
        • rjenkinsgbundefined
          rjenkinsgb @Catalin_RO
          last edited by

          @catalin_ro said in Why not brushless motors in direct drive extruders?:

          Unless they are variable reluctance ones!

          Yes, but only permanent magnet types are used in such as 3D printers, as far as I'm aware?

          Robert J.

          Printers: Overlord pro, Kossel XL+ with Duet 6HC and "Frankentron", TronXY X5SA Pro converted to E3D toolchange with Duet 6HC and 1LC toolboards.

          1 Reply Last reply Reply Quote 0
          • zaptaundefined
            zapta @Catalin_RO
            last edited by

            @catalin_ro said in Why not brushless motors in direct drive extruders?:

            Extruding is all about torque at relative low RPM

            I am not an expert but isn't this what gears do, trading between torque and speed?

            Catalin_ROundefined 1 Reply Last reply Reply Quote 0
            • zaptaundefined
              zapta @Catalin_RO
              last edited by

              @catalin_ro said in Why not brushless motors in direct drive extruders?:

              And the pricing... the driver is a merely 179EUR

              This is probably a matter of demand. With sufficient demand, this can be a much lower cost IC. The question is, is it useful for large scale applications?

              Catalin_ROundefined 1 Reply Last reply Reply Quote 0
              • Catalin_ROundefined
                Catalin_RO @zapta
                last edited by

                @zapta said in Why not brushless motors in direct drive extruders?:

                I am not an expert but isn't this what gears do, trading between torque and speed?

                Of course, but those gears and their supporting plates start adding to the weight. And the whole discussion started from the 30g BLDC motor.

                1 Reply Last reply Reply Quote 0
                • Catalin_ROundefined
                  Catalin_RO @zapta
                  last edited by

                  @zapta said in Why not brushless motors in direct drive extruders?:

                  This is probably a matter of demand. With sufficient demand, this can be a much lower cost IC. The question is, is it useful for large scale applications?

                  Demand builds up when there is a real need for such a solution. I see a need for it in completely different applications, but not in a 3D printer, not even in a prosumer one. In a professional one, maybe!

                  Has anyone complained about the steppers limiting the performance or the quality of the 3D printers on this forum? I have not personally checked, but from already 4 years of browsing I don't recall anything significant. Of course, I'm not discussing about faulty steppers or super cheap steppers assembled in a barn in China (by the pigs grown up for feeding the family over the next year) or poorly chosen (wrong size for the job) ones. There are very good quality steppers at very decent prices, most of them manufactured in China. And they are not even difficult to find.

                  So with a relatively low demand, combined with the high current involved in those drivers (120A peak current! those transistors are anything but cheap!) I don't see the solution getting significantly cheaper. Overall you must also factor in the high current power supply. 24V at 60A is almost 1.5kW peak power for one of these motors. While the average required power is significantly lower, the PSU should be ready to handle those peak currents. Look at this just for reference - https://www.onlinecomponents.com/en/mean-well-usa/rsp200024-43879729.html.

                  As for recognized professional solutions, check this servo with integrated driver - https://www.sorotec.de/shop/JMC-Servo-Motor-with-integrated-driver-100-Watt---36-Volt---3000-1-min.html. Significant torque with very high speed as 36V and 6A peak current.

                  zaptaundefined 1 Reply Last reply Reply Quote 0
                  • zaptaundefined
                    zapta @Catalin_RO
                    last edited by zapta

                    @catalin_ro, I don't know much about the technical aspects or the market potential, to have an opinion.

                    BTW, Skyentific on youtube often deal with low speed, high torque motors for his robotic actuators. It's an interesting channel. These are high pole count motor, sometimes with additional gearing.

                    https://www.youtube.com/results?search_query=Skyentific+actuator

                    Catalin_ROundefined rjenkinsgbundefined 2 Replies Last reply Reply Quote 0
                    • Catalin_ROundefined
                      Catalin_RO @zapta
                      last edited by

                      @zapta Quite interesting. Those might be suitable for axis 4 and 5 in a prosumer CNC...

                      zaptaundefined 1 Reply Last reply Reply Quote 0
                      • zaptaundefined
                        zapta @Catalin_RO
                        last edited by

                        This video has a teardown of such an actuator. Plenty of poles and a planetary gear for torque, and a smart builtin controller.

                        https://www.youtube.com/watch?v=Mhxz2Bj2RXA&t=615s

                        It's not light and not cheap but interesting. šŸ˜‰

                        1 Reply Last reply Reply Quote 0
                        • rjenkinsgbundefined
                          rjenkinsgb @zapta
                          last edited by

                          @zapta said in Why not brushless motors in direct drive extruders?:

                          Skyentific on youtube often deal with low speed, high torque motors for his robotic actuators.

                          Those are clones or descendants of the MIT "Cheetah" robot actuators.

                          They were originally a modified open-loop motor for a large drone, with a hall position sensor and epicyclic gearbox included, to allow them to function as fully commutated BLDCs.

                          And, they specifically have the ability to be back-driven to accept the weight and shock loading in a robot limb application to emulate biological muscle & limb elasticity, without a high-ratio gearbox that would be damaged by such loading.

                          The originals are clearly visible in this clip:
                          https://www.youtube.com/watch?v=xkfXW6XMXao

                          James Bruton came up with a lower cost DIY version, using generic drone motors with belt reduction rather than the custom epicyclic gearing:
                          https://youtu.be/Id11PWxnd4M?list=PLuzW8n0FM__UQutfHUF7jf4jbZwmWM1L6&t=196

                          Robert J.

                          Printers: Overlord pro, Kossel XL+ with Duet 6HC and "Frankentron", TronXY X5SA Pro converted to E3D toolchange with Duet 6HC and 1LC toolboards.

                          1 Reply Last reply Reply Quote 0
                          • Perttiundefined
                            Pertti
                            last edited by

                            Thanks for everybody showing interest around this topic. Looks like reducing weight increases costs as usual.

                            Pertti
                            ā€œA winner is just a loser who tried one more time.ā€
                            George M. Moore, Jr.

                            1 Reply Last reply Reply Quote 0
                            • Perttiundefined
                              Pertti
                              last edited by

                              Ha-haa, here it is,found in Hollow shaft extruder thread:
                              https://www.youtube.com/watch?v=f0SuaIMxAs0

                              Pertti
                              ā€œA winner is just a loser who tried one more time.ā€
                              George M. Moore, Jr.

                              o_lampeundefined 1 Reply Last reply Reply Quote 1
                              • o_lampeundefined
                                o_lampe @Pertti
                                last edited by

                                @Pertti Now you can enjoy your "told you so..." moment. Only 18 month later 😬
                                ODrive was a starting point, but simpleFOC took the edge off cost-wise. (and it's open source)
                                Too bad, there are only a few driverboards available. Most of them are DIY projects, which we have to order from jlcpcb.

                                Perttiundefined 1 Reply Last reply Reply Quote 0
                                • Perttiundefined
                                  Pertti @o_lampe
                                  last edited by

                                  @o_lampe I like this group because of this habit of sharing and commenting innovations.

                                  Pertti
                                  ā€œA winner is just a loser who tried one more time.ā€
                                  George M. Moore, Jr.

                                  CNCModellerundefined 1 Reply Last reply Reply Quote 0
                                  • CNCModellerundefined
                                    CNCModeller @Pertti
                                    last edited by

                                    @Pertti @o_lampe I've bought the shields from here in the past and they seem to be good quality. It only takes a couple of weeks to arrive in the UK

                                    SimpleFOC Shield v2.0.4 FOC BLDC servo stepper motor controller brushless motor driver board develop card

                                    https://a.aliexpress.com/_mPDYIZC

                                    Polar Duet3 Mini + 1HCL
                                    https://youtube.com/playlist?list=PLWjZVEdMv1BY82izahK45qKh-hp3NFkix
                                    Wanhao D4S: Duet2
                                    https://forum.duet3d.com/post/296755
                                    K40 Laser, Duet2
                                    https://forum.duet3d.com/post/312082
                                    Wanhao D5S
                                    https://www.youtube.com/CNCModellerUK

                                    o_lampeundefined 1 Reply Last reply Reply Quote 1
                                    • o_lampeundefined
                                      o_lampe @CNCModeller
                                      last edited by

                                      @CNCModeller These are the official boards, but there are a few designs from forum members. Some are all_in_one boards with STM32 MCU, motor driver and magnetic or optical sensor. None of them are for sale, only by JLCPCB-order.

                                      CNCModellerundefined 1 Reply Last reply Reply Quote 0
                                      • CNCModellerundefined
                                        CNCModeller @o_lampe
                                        last edited by

                                        @o_lampe yeah I have a few different ones, including ones I've got from JLC but for anyone wanting to just have a go they're perfectly usable.

                                        Polar Duet3 Mini + 1HCL
                                        https://youtube.com/playlist?list=PLWjZVEdMv1BY82izahK45qKh-hp3NFkix
                                        Wanhao D4S: Duet2
                                        https://forum.duet3d.com/post/296755
                                        K40 Laser, Duet2
                                        https://forum.duet3d.com/post/312082
                                        Wanhao D5S
                                        https://www.youtube.com/CNCModellerUK

                                        o_lampeundefined 1 Reply Last reply Reply Quote 0
                                        • o_lampeundefined
                                          o_lampe @CNCModeller
                                          last edited by

                                          @CNCModeller I'm currently playing around with used hoverboard motors and controllers.
                                          There is a github group that has hacked the controller board and offers firmware with FOC, too.
                                          Can't compare them yet with simpleFOC, but in one point they are ahead of them which is interesting for my wind-turbine project. (regen-braking)

                                          1 Reply Last reply Reply Quote 0
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