Noise level at very high speeds with interpolated microstepping



  • I built a sand table that uses a corexy mechanism. The table is large and I run it at 500 mm/sec using a pair of NEMA-23 motors (that I had handy) driven by the smoothieboard that came out of my printer when I installed the Duet.

    At that speed, and with NEMA-23 motors, it's a bit noisy. I want to try to reduce the noise level by switching to NEMA-23 motors, using anti vibration mounts for them, and maybe change the controller to a Duet so I can run interpolated microstepping.

    The mechanism currently uses 40 tooth drive pulleys and the motors are spinning at 6.25 revs/sec to hit 500 mm/sec. Any idea if the interpolated ustepping will quiet the motors at that speed?



  • Interpolation should quiet down the motors until RRF starts double-stepping due to step frequency exceeding whatever the doubling threshold is these days. A 1.8 degree stepper at 1/16th stepping and 6.25 rev/sec is 20 kHz. Don't know what the current step doubling threshold is though. @dc42 ?


  • administrators

    RRF no longer switches to double- or higher stepping, because that proved to be incompatible with step-servo drivers such as ClearPath, which need a smooth pulse train. Instead it switches to calculating the time required for 2 or 4 or 8 steps instead of just one step, and it interpolates within that time interval to generate the individual pulses.

    Using 1.8deg Nema 23 motors, I would expect enabling interpolation or increasing microstepping to x32 to reduce noise.



  • Actually, I made an error in the first post. The table has NEMA-23 motors and I intend to switch to NEMA-17 motors for reduced vibration and noise. Interpolated microstepping from a Duet board should be the icing on the cake.

    Thanks.


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