Faster / Better home-z possible?



  • In looking at a way the hasten z-probing - while increasing accuracy, I executed the following but it caused my Z0 to be offset / wonky. The first two lines are my normal routine, but I added the second to perform a slow pass - but it wasn't accurate.

    M558 P9 C"^zprobe.in" H5 F800 T8000                        ; BLTouch, connected to Z probe IN pin - fast
    G30                                                        ; home Z by probing the bed
    M558 P9 C"^zprobe.in" H5 F60 T6000                         ; BLTouch, connected to Z probe IN pin - slow
    G30
    

    Could / Should I use the following?

    M558 F800                                                  ; BLTouch, connected to Z probe IN pin - fast
    G30                                                        ; home Z by probing the bed
    M558 F60                                                   ; BLTouch, connected to Z probe IN pin - slow
    G30
    

    Or is there a better way to shift probing depth speed?

    Thanks,
    Kolbi



  • This is how I do my Z homing.
    Note the A10 bit - this probes until two successive probe runs agree within a certain range. It does up to 10 probes. It will stop if two runs agree and it will fault out if there is no agreement within 10 runs.
    This is for a BLTouch.
    For mapping the bed, I also lower jerk and acceleration.

    M558 F2000 A1 ; set for rapid decent for one probe
    G30 ; do quick probe
    ;this is to rapidly lower the nozzle in case it is quite high
    M558 F60 A10 ; return to normal (slow) probing speed
    G30 ; home Z by probing the bed



  • Thanks @jens55 Just got done with a print, tested some options, and found this to work nicely. Nice use on the 'A' option - thanks for that.

    G1 X105 Y105 F6000                                         ; go to probe point
    
    M558 F1000                                                 ; fast z-probe, first pass  
    G30                                                        ; home Z by probing the bed
    G1 H0 Z5 F400                                              ; lift Z to the 5mm position
    
    M558 F50 A9                                                ; slow z-probe, second pass  
    G30                                                        ; home Z by probing the bed
    G1 H0 Z5 F400                                              ; lift Z to the 5mm position
    
    M558 F200 A1                                               ; normal z-probe, set to normal speed  
    

  • administrators

    @Kolbi said in Faster / Better home-z possible?:

    Could / Should I use the following?

    M558 F800                                                  ; BLTouch, connected to Z probe IN pin - fast
    G30                                                        ; home Z by probing the bed
    M558 F60                                                   ; BLTouch, connected to Z probe IN pin - slow
    G30
    

    Yes, there is no need to redefine the Z probe type when just changing the other parameters. Also, lifting Z between the two G30 probes (as you are now doing) is probably needed.



  • Thanks @dc42 , @jens55 !



  • Hi,

    I would not be comfortable use A1 as the default setting.

    It's fine for doing your "high speed" probe but for everything else I would at least use A2. I use A5.

    Frederick



  • @fcwilt Thanks Frederick!



  • Hi again.

    Just FYI did you know you can force the averaging of a fixed number of readings?

    For example A5 S-1 will cause 5 readings to be taken and the average computed.

    Frederick



  • @fcwilt Just so I'm square on this; when A5 is used without the S-1 switch it will conduct up to five probes or until two back-to-back probes match, and the S-1 switch will cause it to probe 5 times and then yield the average of those 5?



  • AH... got it:

    The A and S parameters control multiple probing. Probing is repeated until two consecutive probe attempts produce results that differ by no more than the S parameter; then the average of those two results is used. However, if the number of attempts specified by the A parameter is reached without getting two consecutive results within tolerance of each other, no further probe attempts are made and the average result of all the attempts is used.



  • @Kolbi said in Faster / Better home-z possible?:

    @fcwilt Just so I'm square on this; when A5 is used without the S-1 switch it will conduct up to five probes or until two back-to-back probes match, and the S-1 switch will cause it to probe 5 times and then yield the average of those 5?

    Correct.

    Consider, getting two consecutive readings doesn't mean that the readings are accurate, just that they are the same, within the tolerance specified by a positive S value.

    The downside to averaging is it takes longer.

    Frederick



  • @fcwilt said in Faster / Better home-z possible?:

    Hi again.

    Just FYI did you know you can force the averaging of a fixed number of readings?

    For example A5 S-1 will cause 5 readings to be taken and the average computed.

    Frederick

    Thanks Frederick - did not know that!


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