From marlin firmware to reprap firmware for Prusa i3 MK3S

  • I am also a beginner trying to understand the firmware values and getting to know my printer before I actually get the duet so please bear with me, do let me know when I have gotten the values or calculations wrong

    Relevant files for prusa marlin:



    In the General page of reprap configurator:

    Homing speed(first pass) and Homing speed(second pass)

    I couldn't find an equivalent in the marlin headers, closest are #define HOMING_FEEDRATE {3000, 3000, 800, 0} // set the homing speeds (mm/min) but those are homing feedrates for individual axes and homing speed first and second pass doesn't indicate any axes

    Travel speed

    In Configuration.h I can find #define XY_TRAVEL_SPEED 8000 in mm/min so I would have to convert it to mm/s by dividing by 60 = 133.33

    Z dive height

    There doesn't seem to be an equivalent in the marlin headers, what am I looking for? Is it MESH_HOME_Z_SEARCH?

    In the motors page:

    I have to set the microsteps to 256 since duet wifi uses tmc2660 which has 256 microsteps, couple that with a nema 17 of 200 steps I get 51200 steps per revolution. At 20 teeth pulleys and using GT2 2mm pitch for x and y it is 40 mm per revolution which gives 1280 steps/mm. As the lead screw on the z axis has 8mm pitch 51200/8 = 6475 steps/mm

    How do I calculate steps/mm for extruder? Related values from marlin:

    #define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,280} // in marlin using einsy rambo at 16 microsteps

    How do I calulate the max speed change, max speed, acceleration and motor current? Here are related values that I can find from marlin:

    #define DEFAULT_MAX_ACCELERATION {1000, 1000, 200, 5000} // (mm/sec^2) max acceleration (M201)

    #define DEFAULT_MAX_ACCELERATION_SILENT {960, 960, 200, 5000} // (mm/sec^2) max acceleration (M201), silent mode

    #define DEFAULT_ACCELERATION 1250 // X, Y, Z and E max acceleration in mm/s^2 for printing moves (M204S)

    #define TMC2130_CURRENTS_H {16, 20, 35, 30} // default holding currents for all axes

    #define TMC2130_CURRENTS_R {16, 20, 35, 30} // default running currents for all axes

    #define TMC2130_CURRENTS_R_HOME {8, 10, 20, 18} // homing running currents for all axes

    In the Endstops page of reprap configurator:

    I have to set all endstops to sensorless and location to be low end because

    #define X_HOME_DIR -1#define Y_HOME_DIR -1#define Z_HOME_DIR -1

    As for Z probe, I am clueless, the i3 mk3s uses the PINDA probe which is an inductive sensor, I assume it is either simple modulated IR probe or unmodulated/smart IR probe, how can I find the trigger height and trigger value? I also have the offsets of x and y but where do I input the z offset and find the probing speed?


  • @0x00 said in From marlin firmware to reprap firmware for Prusa i3 MK3S:

    I have to set the microsteps to 256

    better use 16 microsteps and enable the interpolation to 256.

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