RRF 3.0 stallguard



  • Hi, I just updated from 2.0 to 3.0 on a corexy, I used the online configurator, but the stallguard does not work, the cart does not stop, while in 2.0 it worked perfectly.

    In config,g i've put :

    ; Endstops
    M574 X1 S3 ; configure sensorless endstop for low end on X
    M574 Y1 S3 ; configure sensorless endstop for low end on Y
    M574 Z1 S2 ; configure Z-probe endstop for low end on Z

    and in homex.g (for example) i've put:

    M915 P0:1 S0 R0 F0 H400; both motors because corexy; Sensitivity 10, don't take action, don't filter, 400steps/sec
    G91 ; relative positioning
    G1 H1 X-325 F1800 ; move quickly to X axis endstop and stop there (first pass)
    G1 X5 F6000 ; go back a few mm
    G90 ; absolute positioning

    Someone can help me please ?

    Thanks a lot


  • Moderator

    @Adryzz H400 on your M915 command sounds high. The 'H' parameter is the Minimum motor full steps per second for stall detection to be considered reliable, and set to 400 full steps per second. You haven't posted your full config.g, but if you're running, say, GT2 belt on 20-tooth pulleys with 1.8º motors, for 80 steps per mm, at 16x microstepping this is 5 full steps per mm. At 400 full steps per second, the feed rate you need to home at is, at least, 400/5=80mm/s, or 4800mm/min (F4800). Your homing speed is set to F1800, so even if you have 0.9º motors and double the number of full steps per mm, it's still too slow to trigger stall detection.

    From https://duet3d.dozuki.com/Wiki/Stall_detection_and_sensorless_homing#Section_Limitations_of_stall_detection

    To avoid this, the firmware allows you to set minimum speeds (in motor full steps per second) below which stall indications will be ignored.

    You'll need to either/both decrease H (200 is default) and increase the feedrate of the homing move until the number of full steps is above H.

    You should probably also reduce the motor current during stall detection with M915.

    Ian


  • administrators

    This is what I use on my E3D Tool Changer, which is also CoreXY, running RRF 3.01beta1:

    ; Endstops
    M574 X1 Y1 S3 		; Set X / Y endstop stall detection
    M574 Z0 		; No Z endstop
    ...
    ;Stall Detection
    M915 H200 X Y S3 R0 F0 	; set X and Y to sensitivity 3, do nothing when stall, unfiltered
    
    

    The XY steps/mm is 100 and the speed (F parameter) of XY homing moves is 3000.

    HTH David


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