Question about Stall Detection



  • Hi there,

    I'm starting to use the Stall detection as I'm having some layer shifting (I've changed back from CF to steel in my rods, and I think I still need to increase the power for the drivers a bit more), and I've tuned the stall detection (I'm not having false positives so far).

    Here my question, for the moment, I've configured the stall detection to just log it, and I've run a few prints where I had layer shifting, and I was able to see the layer shifts in the PanelDue, but now I want to change the configuration to be aware of it and re-home, but I'm not quite sure how R3 works.

    As I see in the documentation, if I select R3 instead of R1 (which is what I've now), it will "pause and execute a restart"โ€ฆ. but what is a restart? home of the axis that failed? (as I'm using a CoreXY, I need to re-home both, X and Y, not just the stalled one), or a script/macro where I can put whatever?

    Thanks!


  • administrators

    Good question, because I forgot to document it! You need to create file sys/rehome.g and put the following commands in it:

    • Retract a little filament
    • Raise the head a little
    • Re-home whatever axes you want to (probably just X and Y on a Cartesian or CoreXY printer)
    • Restore the original head position and undo the retraction, just as in the resume.g file.

    Please test this before relying on it!



  • @dc42:

    Good question, because I forgot to document it! You need to create file sys/rehome.g and put the following commands in it:

    • Retract a little filament
    • Raise the head a little
    • Re-home whatever axes you want to (probably just X and Y on a Cartesian or CoreXY printer)
    • Restore the original head position and undo the retraction, just as in the resume.g file.

    Please test this before relying on it!

    Thanks!

    For testing it, can you suggest a better way than to stop the head by hand and see if it works as expected? ๐Ÿ˜„

    Regards


  • administrators

    @okercho:

    @dc42:

    Good question, because I forgot to document it! You need to create file sys/rehome.g and put the following commands in it:

    • Retract a little filament
    • Raise the head a little
    • Re-home whatever axes you want to (probably just X and Y on a Cartesian or CoreXY printer)
    • Restore the original head position and undo the retraction, just as in the resume.g file.

    Please test this before relying on it!

    Thanks!

    For testing it, can you suggest a better way than to stop the head by hand and see if it works as expected? ๐Ÿ˜„

    Regards

    You could send a M915 command to set the stall detection threshold artificially low temporarily.



  • Ok, I've been testing it, and I've found that the homing works perfectly, but the stall detection during the print since I changed the driver power to 1'5 doesn't work so wellโ€ฆ Maybe is due to the motor temperature? I can feel it warm, but not hot.

    I've tried during a print to force an stall, and if I setup it to "M915 P0:1 S3 F0 R3", it doesn't detect the stall even if I do a lot of force to stop it (and I actually stop it), however, if I setup it to S2, it gives me a lot of false positives... how can that be?

    I forgot to test to change F value, maybe that will reduce the false positives? will it affect the homing?

    Cheers


  • administrators

    1. You can use F0 for homing and F1 for stall detection, if that helps.

    2. Have you tried using S2 but either decreasing allowed acceleration (and maybe jerk) or increasing the H parameter in M915?



  • @dc42:

    1. You can use F0 for homing and F1 for stall detection, if that helps.

    2. Have you tried using S2 but either decreasing allowed acceleration (and maybe jerk) or increasing the H parameter in M915?

    Will try both and report back, thanks ๐Ÿ™‚


 

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