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    M3 Snnn - Programmed vs Actual Speed

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    Tuning and tweaking
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    • Nightowlundefined
      Nightowl @jay_s_uk
      last edited by

      @jay_s_uk
      It does seem quite stable. The only exception was with the last list of speeds, where one of the speeds 'hunted' a bit, like a vehicle engine with a touch of fuel starvation, if you know what I mean?

      Few things are more dangerous than taking the advice of someone who thinks he knows what he's doing.
      I'm still on my learning curve, so take everything I say with caution!

      RatRig 1075, Duet3 MB6HC, Sorotec SFM 1000 PV-ER milling motor, Hobbyist

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

        @Nightowl yea, that's what mine sounds like. Maybe I need to revisit my setup

        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

        Nightowlundefined 1 Reply Last reply Reply Quote 0
        • Nightowlundefined
          Nightowl @jay_s_uk
          last edited by

          @jay_s_uk
          Whilst checking the speeds, I also checked the noise. At...

          Ambient = 45dBa
          S4000 = 65dBa
          S10000 = 75dBa
          S18000 = 83dBa
          S25000 = 84dBa
          

          Few things are more dangerous than taking the advice of someone who thinks he knows what he's doing.
          I'm still on my learning curve, so take everything I say with caution!

          RatRig 1075, Duet3 MB6HC, Sorotec SFM 1000 PV-ER milling motor, Hobbyist

          1 Reply Last reply Reply Quote 1
          • Nightowlundefined
            Nightowl
            last edited by

            So, I've done a bit of tuning with mixed results.

            M3 Input - Untweaked	- Tweaked
            S4000	– 4050		– 4060
            S6000	– 6266	 	– 6550
            S8000	– 8150	 	– 8485
            S10000	– 9955	 	– 10400
            S12000	– 11665		– 12270
            S14000	– 13473		– 14030
            S16000 	– 15304		– 15870
            S18000 	– 17065		– 17680
            S20000 	– 18867		– 19390
            S22000 	– 20726		– 21190
            S24000	– 22425		– 22880
            S25000	– 22608		– 23050
            

            There doesn't seem to be a regular variation, so I was wondering if anyone else has managed to work this out and achieve accurate speeds.

            Thanks

            Few things are more dangerous than taking the advice of someone who thinks he knows what he's doing.
            I'm still on my learning curve, so take everything I say with caution!

            RatRig 1075, Duet3 MB6HC, Sorotec SFM 1000 PV-ER milling motor, Hobbyist

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

              @Nightowl
              Did you measure RPM under load or without?
              I think, the RPM control loop works best under load? (except with 3-phase PM brushless motor)
              All other motors, (brushed DC or asynchron) are less accurate

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

                @Nightowl said in M3 Snnn - Programmed vs Actual Speed:

                I'll do that tomorrow, as it's too dark to go out now

                How dare you to name yourself nightowl ? 😄 😄

                Nightowlundefined 1 Reply Last reply Reply Quote 0
                • Nightowlundefined
                  Nightowl @o_lampe
                  last edited by

                  @o_lampe said in M3 Snnn - Programmed vs Actual Speed:

                  @Nightowl said in M3 Snnn - Programmed vs Actual Speed:

                  I'll do that tomorrow, as it's too dark to go out now

                  How dare you to name yourself nightowl ? 😄 😄

                  🙄 🙄

                  Few things are more dangerous than taking the advice of someone who thinks he knows what he's doing.
                  I'm still on my learning curve, so take everything I say with caution!

                  RatRig 1075, Duet3 MB6HC, Sorotec SFM 1000 PV-ER milling motor, Hobbyist

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                  • Nightowlundefined
                    Nightowl @o_lampe
                    last edited by

                    @o_lampe said in M3 Snnn - Programmed vs Actual Speed:

                    @Nightowl
                    Did you measure RPM under load or without?
                    I think, the RPM control loop works best under load? (except with 3-phase PM brushless motor)
                    All other motors, (brushed DC or asynchron) are less accurate

                    No, I didn't test it under load to be honest. It may have been optimistic on my part, but the blurb indicated the speed is maintained under load, so I'm wondering if I should test the voltage output from the PWM converter (as supplied to the milling motor) to see if the issue is there.

                    I have more confidence in the German-built milling motor, than I do in the converter and/or the digital tacho I'm using to test the speed.

                    Few things are more dangerous than taking the advice of someone who thinks he knows what he's doing.
                    I'm still on my learning curve, so take everything I say with caution!

                    RatRig 1075, Duet3 MB6HC, Sorotec SFM 1000 PV-ER milling motor, Hobbyist

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

                      @Nightowl said in M3 Snnn - Programmed vs Actual Speed:

                      the digital tacho I'm using to test the speed.

                      I suspected that too, but those would usually skip pulses. But in you table it reads more pulses at low RPM. Probably false triggering...
                      I had good results with hall sensors. A simple bicycle speedometer (with programmable wheel circumfence) worked well on my wind turbine.

                      Nightowlundefined 1 Reply Last reply Reply Quote 1
                      • Nightowlundefined
                        Nightowl @o_lampe
                        last edited by

                        @o_lampe
                        Perhaps it's time to start another hobby....

                        The idea of using an Arduino with a hall sensor sounds like fun, and I've seen an Arduino kit on Amazon which seems to fit the bill (except for the hall sensor, which is cheap enough), but I wonder if this would be more accurate than a laser measuring the reflection from reflective tape stuck to the spindle's collet nut - which is the method I currently use?

                        Of course, I'd need to learn how to program an Arduino!

                        Few things are more dangerous than taking the advice of someone who thinks he knows what he's doing.
                        I'm still on my learning curve, so take everything I say with caution!

                        RatRig 1075, Duet3 MB6HC, Sorotec SFM 1000 PV-ER milling motor, Hobbyist

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