Nozzle height



  • Re: Nozzle will not start low enough to print
    Phaedrux MODERATOR 31 Jul 2020, 21:54
    @damaged_goods said in Nozzle will not start low enough to print:

    M92 X172.00 ; set movement speed to match m915 H param
    M201 X100.00 ; reduce acceleration
    M566 X100.00 ; reduce maximum instantaneous speed changes (mm/min)
    G1 H1 X-1160 F6000 ; move quickly to X axis endstop and stop there (first pass)
    ; G1 H2 Z-5 F6000 ; lower Z again
    G90 ; absolute positioning
    M92 X80.00 ; set steps per mm back to default
    M566 X900.00 ; set maximum instantaneous speed changes back to normal (mm/min)
    M201 X500.00 ; set ac

    It's quite bizarre to alter your steps per mm in a homing file. What is the reasoning?



  • @damaged_goods Could someone explain what and why it is "bizarre" to alter steps per mm in homing file. I have no reasoning and am never offended to learn something new 🙂



  • the steps per mm depend on your pulleys teeth and the belt pitch
    or the leadscrew pitch.
    not taking into account microstepping which rrf does automatic step conversion.

    so during operation you cant normally change either, its not obvious why you would want to change them.



  • @damaged_goods said in Nozzle height:

    @damaged_goods Could someone explain what and why it is "bizarre" to alter steps per mm in homing file. I have no reasoning and am never offended to learn something new 🙂

    The "steps per mm" settings are determined by the design of your printer.

    They should never need to be changed if the hardware does not change.

    The purpose of the settings is to achieve the correct amount of movement on each axis for movement commands.

    For example, assuming you have issued a G91 to enable relative movement mode, a G1 X10 should move exactly 10mm on the X axis.

    Likewise for Y and Z.

    If the settings are wrong the actual positions will not match the commanded positions and bad things will very likely happen.

    Frederick


  • Moderator

    @damaged_goods said in Nozzle height:

    @damaged_goods Could someone explain what and why it is "bizarre" to alter steps per mm in homing file. I have no reasoning and am never offended to learn something new 🙂

    The steps per mm should be set in the config.g and not in a homing file. Once it's set, it makes no sense to change it unless you have some very specific reason. Otherwise it just doesn't belong there.



  • Thank you everyone


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