Save new Z offset - how on the fly?

  • Can I set new Z offset without going into the config and rebooting. I am not talking about babystepping but real Z offset if changing nozzle/hotend ..

  • Yes, as with any of the gcode commands, you can send the G31 Z command at any time, and doesn't need a restart. I'm not sure if it needs to be homed to take effect though.

  • @phaedrux

    But how do I save it? Will M500 also give me the same z offset when power on off

  • Yes, I think M500 P31 should save the offset value in recent firmwares.

    M500 P31
    G31 trigger height, trigger value and X and Y offsets for each possible Z probe type (in later firmware versions the G31 parameters are not stored unless the P31 parameter is present)

    Can be used in conjunction with G30 S-3 to measure the value and set it. M500 P31 to save it.

    G30 S-3 ; Probe the bed and set the Z probe trigger height to the height it stopped at (supported in RRF 2.03 and later)

  • @phaedrux

    I am not sure I understand. Does this mean I have to write this P31 somewhere? I dont see any G31 line in config overide

  • First you have to set your new Z offset, either by sending G31 Z2.2 in the console, then send M500 P31 to save it to config-override.g.

    Or, if you're using 2.03 you could use G30 S-3 to measure the offset, and use M500 P31 to save it.

    At least that's how I believe it should work.

    What firmware version are you using?

  • @phaedrux

    I am not sure what fw I run but it was the latest official release in january - cant access right now I have network issues. I am so sick of the DWC now I will order a panel due

    I dont know this G30 S-30 command but can read up on it

  • @pro3d said in Save new Z offset - how on the fly?:

    I dont know this G30 S-3

    You may not have access to it yet as 2.03 is still in beta.

  • @phaedrux

    You are such an oracle - You can never leave cause you know to much 🙂

    M500 P31 saves the G31 line in config overide - confirmed. Thanks

    *Retraction update
    BTW I managed to tune retraction, flow and PA for petg on the long bowden Titan CoreXY DIY machine 🙂 Ended up with 3mm retraction and PA @ 0.15 - 60 retract / 30 prime speed - Flow 0.9...

  • @pro3d said in Save new Z offset - how on the fly?:

    BTW I managed to tune retraction, flow and PA for petg on the long bowden Titan CoreXY DIY machine Ended up with 3mm retraction and PA @ 0.15 - 60 retract / 30 prime speed - Flow 0.9...

    Glad you got it tuned up. I'd be interested to see how those settings differed from the previous marlin settings to try and understand how and why settings translate between the two. It seems to be a recurrent issue where people find settings transcribed from marlin into RRF don't seem to behave in the same way.

  • @phaedrux

    I really dont understand why RRF act differently on retraction but it does. I was not able to tune it without PA at all but now it is fine for at least two materials. Still struggling with Carbon fill PETG

    Marlin retraction was very simple and had no holes after priming even with long retract at 6-7 mm but RRF did. I tried using the extra prime amount no luck so finally tried tuning in PA and ended up with some good results for a difficult petg

    Marlin does use absolute extrusion but dont know if that has to do with anything - Now all accel/jerk are exaclty the same as was in Marlin but retraction is lowered from 7 to 3 and PA on with 0.15

    What I find curious is that flow is running at 0.9 as was almost 1 with my Marlin setup - also very strange so I must look into my e-steps ones more

    1_1552596488662_20190314_213549.jpg 0_1552596488660_20190314_213806.jpg

  • I use about 0.1mm to 0.15mm of extra prime on unretraction with PETG and a little bit more with carbon fill. I've found it to be bad at leaving large scars on unretract without it. It seems like it's hesitant to reprime the nozzle. It's almost like the fill material causes a bit of blockage.

    My current preferred settings on my Titan Aero V6 are

    M572 D0 S0.035 	; pressure advance
    M207 S0.85 R0.1 F3200 T2800 Z0.0				; retraction
    M566 X1200 Y1200 ; Jerk
    M204 P900 T4000

    Print at 70mm/s travel at 230mm/s
    0.6 nozzle, printing at 0.3 height and 0.6 width.
    Trying to maximize flow rate for the V6 (~13mm^3/s)
    0.94 flow rate in Slic3r PE.
    Seam aligned to rear.

    alt text
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    That's Amazon Basics black PETG at 255c.

  • @phaedrux
    The most strange thing about carbon filled was printed with microswiss hardened nozzle 0.6 mm but I could not get the walls right with tuning flow. It was printing over 0.8 mm lines at 100% flow and could never get right width on the walls. Nozzle was brand new

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