strange 'ghost' Y axis limit



  • I use my duet 2 wifi with a coreXY printer. Recently I've just changed from a side-by-side dual extruder setup back to a single extruder, so I updated probe offset, re-defined axis min and max limit, mesh compensation pattern, z height etc. Then something strange happened. When I tried to print a model that spans much of the Y axis range, the HE would stop moving in the Y axis hitting somewhere Y=240 but X and Z movements are normal. This means everything beyond Y=240 gets squeezed into a single line at Y=240.....I checked the gcode, no problem there as the G1 Y values go smoothly through Y=240. I then checked config.g. There's no 240 anywhere. Checked the definition of M208 and M574...nothing off there too. So, where's this 240 'invisible wall' coming from?? The only hypothesis I had was that M208 was mis-aligned with actual bed Y position. When homed, i measured the HE position and used the X, Y offset to the nearest bed corner to M208 the origin, per the tutorial on this website. I then put in 305 305 as the max value because my bed measures 310/310, to give a little margin. This apparently was not the problem.

    Since I've made many changes over the past few months experimenting with mechanical tool changers, etc, the problem might be buried somewhere else in the sys folder....could somebody offer other hypotheses to try? really frustrated. thanks

    a section of my config.g:

    ; Axis Limits
    M208 X-24 Y-7 Z0 S1 ; Set axis minima
    M208 X305 Y305 Z340 S0

    ; Endstops
    M574 Y1 S0 ; Set active low and disabled endstops
    M574 X1 S1 ; Set active low and disabled endstops

    ; Z-Probe
    M574 Z1 S2 ; Set endstops controlled by probe
    M558 P5 H5 I1 F120 T6000 ; Set Z probe type to switch and the dive height + speeds
    G31 P500 X20 Y-15 Z0.707 ; Set Z probe trigger value, offset and trigger height
    M557 X10:280 Y10:280 S50 ; Define mesh grid



  • please post all your config files.

    also check the start of your sliced g code.



  • Is the bed size defined incorrectly in your slicer?

    Do you have another rogue M208 somewhere? Do you have any G92 in your homing files resetting positions?


  • administrators

    You can send M208 without parameters to see what values the firmware is using.



  • thanks to all! after another exhausting search, I confirmed that it was in my bed.g......a M208 Y240 I planted a long time ago to accommodate one of the experimental tool changer setup....I didn't have this problem initially because I asked the slicer to G29 before each print, but lately I've begun to manually probe the bed by pressing that 'auto bed compensation' button, which is a G32!

    send M208 without parameter is a godsend...thanks dc42!


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