Question about firmware values using mm/min



  • Hi,

    I have a question whose answer may have it's roots in history.

    The DWC displays things like movement speeds in mm/sec.

    Articles that discuss "tweaking" a printers performance tend to talk about speeds in mm/sec.

    Yet the firmware in certain places uses mm/min.

    Why the different units? It there any technical reason? If mm/sec COULD have been used might a future version allow for that?

    Thanks much.

    Frederick


  • administrators

    GCode was originally invented for CNC machines. They work at much lower speeds than 3D printers, so inches/min or mm/min was a sensible unit.

    RepRapFirmware is consistent in that all speeds used in GCodes are in mm/min, except for one that was added for compatibility with Marlin. Marlin is less consistent: some speeds are in mm/min, others are in mm/sec.



  • @dc42 said in Question about firmware values using mm/min:

    GCode was originally invented for CNC machines. They work at much lower speeds than 3D printers, so inches/min or mm/min was a sensible unit.

    RepRapFirmware is consistent in that all speeds used in GCodes are in mm/min, except for one that was added for compatibility with Marlin. Marlin is less consistent: some speeds are in mm/min, others are in mm/sec.

    Thanks for the information. I figured history was involved.

    If you are ever sitting around one day with nothing to do how about adding a new command to switch the units in the config files from mm/min to mm/sec to be consistent with information displayed on the DWC and such.

    🙂

    Frederick



  • I think it makes more sense to display mm/s in the DWC because slicers generally use mm/s for their speed settings.



  • @phaedrux said in Question about firmware values using mm/min:

    I think it makes more sense to display mm/s in the DWC because slicers generally use mm/s for their speed settings.

    I agree and thus it makes more sense, to me, to use the same, familiar units in configuration files.

    I understand the history but if the only reason for using mm/min is the history I think a change could be considered, even if as an option, as I suggested.

    Frederick


 

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