M221 question

  • Can M221 accept decimal values for detailed tuning? I recognize it can't be set through DWC.. Yes, I'll be testing this myself here very soon, but thought someone might know off the top of their head..

    If not, why not? Thanks

  • Let me clarify.. we are tweaking dimensional accuracy. 95% results in roughly .10mm under and 96% results in roughly .10mm over. So 95.5% should be spot on.. I'll be testing soon and can report back.

  • If you cannot use decimal values could you tweak the extruder steps/mm setting?


  • @oozeBot I'm struggling to understand you usage case. I don't think that tweaking the extrusion factor override percentage is the tool to use for dimensional accuracy compensation. But leaving that aside, do you have a particularly coarse extruder? Assuming it's a worse case, un-geared extruder with (say) only 100 step per mm. That means 1 step is 100th of a mm or 0.01mm. So 1 percent increments of that gives you a resolution of 0.0001mm. Why do you think you need finer adjustment than that?

    And if you you use an extruder with say 3:1 gearing, then the steps per mm with likely be 400 or even 800 if you use 0.9 degree motors so then you be talking a resolution of 0.0000125 mm per 1% increment.

  • Setting M221 to 95.5% seems to work and DWC reports it back to me.. so that's good to know.

    @deckingman - we are using Bondtech BMG extruders with Slice Magnum mosquitos and a .6mm nozzle, and a .9 degree LDO stepper. We only print in ABS. Setting the extrusion factor to 100% results in a part ~.33mm wider in both X and Y. Setting extrusion factor to 90% results in a part ~.40mm narrower in both X and Y. I am running a sample now at 95.5% in hopes it is within +/- ~.10mm in both directions.

    Final edit - setting M221 95.5 worked quite well and resulted in a model within +/- .05mm in both X and Y!

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