large variation in z-probe trigger height



  • SeeMeCNC v3.2 Delta printer with nozzle probe.
    RRF2.05_1 WITH DWC 3.1.1

    I've had a recent rebuild to validate the physical accuracy. Everything is better except now I have a drifting and variable trigger height.

     6/25/2020, 3:31:28 PM 	Stopped at height -0.305 mm
    Stopped at height -0.355 mm
    Stopped at height -0.280 mm
    Stopped at height -0.305 mm
    6/25/2020, 3:31:26 PM 	Stopped at height -0.305 mm
    Stopped at height -0.355 mm
    6/25/2020, 3:31:24 PM 	Stopped at height -0.270 mm
    6/25/2020, 3:31:23 PM 	M98 P"0:/macros/Z Probe Trigger Check"
    Stopped at height -0.320 mm
    6/25/2020, 3:28:45 PM 	Stopped at height -0.315 mm
    Stopped at height -0.335 mm
    6/25/2020, 3:28:43 PM 	Stopped at height -0.345 mm
    Stopped at height -0.290 mm
    6/25/2020, 3:28:42 PM 	Stopped at height -0.310 mm
    Stopped at height -0.315 mm
    6/25/2020, 3:28:40 PM 	M98 P"0:/macros/Z Probe Trigger Check"
    Stopped at height -0.350 mm
    6/25/2020, 3:23:16 PM 	Stopped at height -0.450 mm
    Stopped at height -0.475 mm
    6/25/2020, 3:23:14 PM 	Stopped at height -0.455 mm
    Stopped at height -0.455 mm
    6/25/2020, 3:23:12 PM 	Stopped at height -0.435 mm
    6/25/2020, 3:23:11 PM 	M98 P"0:/macros/Z Probe Trigger Check"
    Stopped at height -0.455 mm
    Stopped at height -0.470 mm
    6/25/2020, 3:22:00 PM 	m500
    6/25/2020, 3:21:18 PM 	M140 P0 S90
    Calibrated 6 factors using 18 points, deviation before 0.078 after 0.072
    6/25/2020, 3:21:18 PM 	G32
    Calibrated 6 factors using 18 points, deviation before 0.078 after 0.072
    6/25/2020, 3:20:22 PM 	g32
    Calibrated 6 factors using 18 points, deviation before 0.103 after 0.079
    6/25/2020, 2:43:57 PM 	g28
    6/25/2020, 2:42:29 PM 	Connection established
    

    I fixed it by changing the line in config.g

    G31 P100 X0 Y0 Z-0.35 to G31 P150 X0 Y0 Z-0.325

    6/25/2020, 10:22:46 PM 	Stopped at height -0.326 mm
    Stopped at height -0.326 mm
    Stopped at height -0.326 mm
    Stopped at height -0.331 mm
    6/25/2020, 10:22:45 PM 	Stopped at height -0.326 mm
    Stopped at height -0.326 mm
    6/25/2020, 10:22:43 PM 	Stopped at height -0.331 mm
    Stopped at height -0.326 mm
    Stopped at height -0.331 mm
    6/25/2020, 10:22:42 PM 	M98 P"0:/macros/Z Probe Trigger Check"
    Stopped at height -0.331 mm
    6/25/2020, 10:20:33 PM 	Stopped at height -0.326 mm
    6/25/2020, 10:20:32 PM 	Stopped at height -0.316 mm
    Stopped at height -0.321 mm
    Stopped at height -0.316 mm
    6/25/2020, 10:20:30 PM 	Stopped at height -0.316 mm
    Stopped at height -0.316 mm
    6/25/2020, 10:20:28 PM 	M98 P"0:/macros/Z Probe Trigger Check"
    Stopped at height -0.311 mm
    

    And now the trigger results of the G30 S-1 are within 0.02 and this seems good but is there a problem I am covering up doing this that I should fix instead?


  • Moderator

    What is the actual probe?
    What is your M558?

    It seems more consistent after your change of sensitivity, so that seems like a good thing. Can you reliably move G1 z0 and touch the bed?



  • @Phaedrux
    Probe is a SeeMeCNC customized version of the Smart Effector. (SE300 is their name for it).

    The M558 is:

    M558 P8 I0 A10 S0.02 R0.4 H5 F2500 
    

    I have .9 degree steppers.

    I'll play with G1 Z0 and check the bed distance when I go up to the printer tonight. I'm mostly still trying to pin down first layer issues. My last thread in the forum led me to do a complete rebuild and replace the trucks, steppers, and iddler bearings of my Rostock Max v3.2 and that helped with the backlash that was giving me issues and now I'm trying to tweak things better.

    I have had successful prints since making the change but I'm playing with magic when it comes to tweaking the probe settings (M558 and G31).


  • Moderator

    Well there's more to the first layer than just the height. And even if you can't get the height perfect you can compensate with flow rate and extrusion width and heat.



  • @Phaedrux

    Yes, I just want to make sure I'm not covering up some other problem by tweaking the probe sensitivity so much from the default. If a value of 100 works for nearly all circumstances it makes me wonder what could be causing my need to tweak to eliminate variability and what mechanically could be causing the need to increase the value.

    Since I don't exactly understand what I'm changing here I'm asking.

    I've done the extruders and the line width and dimensional accuracy calibrations and they have tweaked in to my satisfaction. This is the last bit to adjust.


  • Moderator


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