Issue with probe and homing Z



  • Hello all,

    So I have my corexy printer switched over to a duet wifi board. I'm using the IR sensor ( https://www.filastruder.com/collections/electronics/products/mini-differential-ir-height-sensor ) mounted to an e3d hotend and have calibrated the trigger height at 1.61 mm. The following section is to configure the probe:

    G31 P500 X0 Y20 Z1.61 ; Set Z probe trigger value, offset and trigger height
    
    

    Full configuration is at http://pastebin.com/jJfsCJ1s ( just config.g )

    When I start a print ( http://pastebin.com/r5TPhw8S ) X, Y and Z home and then the print starts. Sadly, the Z axis stays at 1.61 even though there is gcode in there to set the Z to .2mm for the first layer.

    Obviously I have something configured wrong I just don't see what. Any ideas?


  • administrators

    What do you have in your homeall.g and homez.g files, and what you you have in your slicer start gcode?

    If you home all and then send G1 Z0, the nozzle should lower until just touching the bed. Does it?



  • At a quick glance, it looks to me that it's gcode file you are trying to print and it's probably your start gcode. There is a Z 0.2 move (line 194) which is fine, but later on (line 200) there is a G28 ; home all. The G28 needs to be before the first Z move. HTH

    Edit - Sorry DC - looks like we were typing at the same time.



  • Ah interesting @deckingman - I'd bet that is it.

    I think in the homeall.g I updated it to home X, Y and Z separately. But that extra G28 and how the homeall works it would only home to my probe trigger offset which is 1.61. I'd bet thats the issue thanks guys!

    Will try it out tonight.



  • Yes, essentially after you home Z the machine will remain at the trigger height until it is told otherwise. When you run your gcode file, it sees the G1 Z0.2 command which will move it to Z=0.2 but then after that, it gets another home command which will leave it at the trigger height. It'll be easy to check - just use notepad++ or some such to delete the G28 or move it to before the G1 Z0.2 but of course, you'll need to sort out the start gcode that put it there in the first place. HTH
    Ian


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