Less then 1 step pr. mm?



  • On the Duet3 I am trying to configure a 300x300mm printer to think it's 10x10 meter. This means a steps/mm at around 0.4. I can't seem to get the firmware to accept less then 1 step/mm.

    Is there a trick to make this work?



  • @Kulitorum I'd imagine that it's because the steps per mm are actually micro-steps and you can't have a fraction of a micro-step. Assuming you are using 16X micro-stepping then increasing it to 64X or above will get you to whole numbers but still fractionally. If the steps per mm are indeed 0.4, then you'd need some multiple of 2.5 X higher to get whole numbers which could be a problem given that you only have 16, 32, 64, 128 or 256 to choose from. In which case you might need some sort of mechanical gearing.


  • administrators

    The M92 command has a minimum steps/mm of 1.0 in order to prevent zero or negative values being used, which could make it crash. But I think you could get around it to some extent as follows. If you set the microstepping to x256, then set steps/mm to 1.0, then change microstepping to x16 then the steps/mm will get recalculated to 1.0 * (16/256), bypassing the check.



  • @Kulitorum said in Less then 1 step pr. mm?:

    Is there a trick to make this work?

    you could try setting it up in inches and changing back to mm, or if your workflow allows you to use meters as units when you export you could always just set up the machine to use 400steps pr meter.


  • administrators

    @bearer said in Less then 1 step pr. mm?:

    you could try setting it up in inches and changing back to mm

    M92 and most other settings are always in mm in recent firmware versions.



  • @dc42 said in Less then 1 step pr. mm?:

    M92 and most other settings are always in mm in recent firmware versions.

    i wondered if i had read something to that effect, but thanks for confirming



  • Yep, got it to work with 256 microsteps and 2 steps/mm. Thank you.



  • @Kulitorum said in Less then 1 step pr. mm?:

    On the Duet3 I am trying to configure a 300x300mm printer to think it's 10x10 meter.

    this got me interested. would you share with us what you are building?
    a 10x10 meter printer sounds interesting.


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