Trouble with C Axis

Discussion in 'Tool heads & ToolChanger' started by Norman Thompson, Nov 9, 2019.

  1. Norman Thompson

    Joined:
    Sep 18, 2019
    Messages:
    7
    Likes Received:
    0
    When using M92 how is the C axis setting related to the X,Y& Z settings?
    I am trying to fine tune X,Y and Z so that the printed dimension is extremely close if not the same as the drawn dimension.
    So I changed the M92 line in config from
    M92 X100 Y100 Z1600 C100 E417:417:417:417
    to
    M92 X99 Y99 Z1584 C100 E417:417:417:417
    The issue is that when I reload this updated firmware the tool changer head no longer engages with the desired tool. It looks like the head is stopping about 1mm short of the tool so that C's rotating spigot can no longer engage with the tool.

    How do I adjust C to fix this issue? What is the formula?

    If I revert back to the default M92 line then everything works again.
     
  2. Greg Holloway

    Greg Holloway Administrator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    911
    Likes Received:
    591
    Hi Norman,

    Each axis is independant of the other, chaning one does not affect the other.

    If you adjust the steps per mm it will mean the toolhead now goes to a different position than it did before. The printer doesn;t actually know what a mm is, or how far it moves when it is commanded.

    What you need to do is adjust the scripts so that the toolhead now goes to a different position, one which is now defined by your new steps per mm.

    To help explain, a mile is 5280 foot. so the feet per mile is 5280. if you change the steps to 5000, and then say you want to walk 1 mile, you have now not gone as far as you did before.

    it is a similar thing with steps per mm and the position of the tools, whereas it was 100 for a mm and you have said go 1mm,because you have changed the number of step for a mm, the old values for the positin of the tools, are no longer correct.
     
  3. Norman Thompson

    Joined:
    Sep 18, 2019
    Messages:
    7
    Likes Received:
    0
    Is there a formula for C or is it all trial & error?
    From what I have now I need C to advance about 1mm more.
    I do not want to change X, Y or Z as that will change the absolute printed dimensions.
    To make C move about another 1mm do I change C to 101 or 99?
    Please advise.
    Thanks.
     
  4. Norman Thompson

    Joined:
    Sep 18, 2019
    Messages:
    7
    Likes Received:
    0
    Greg,

    I can see the error in my thinking. It is not C that needs to cahnge at all.
    By changing the X, Y and Z steps/mm I have effectively moved the origin so that the X-Y location of the toolchanger head is incorrect when it
    comes to engaging with the tool head. How to I adjust the origin point when changing the steps/mm so that the toolchanger head can still engage
    with the tool?

    Thanks,

    Norman
     
  5. Norman Thompson

    Joined:
    Sep 18, 2019
    Messages:
    7
    Likes Received:
    0
    If I go through the commissioning steps in the manual then for T0 where it says to move the tool changer head to position Y243
    then the toolchanger head needs to go about another 2mm (ish) to Y245 for the head to engage correctly with the tool. If I try
    to reach Y245 nothing happens. I think the firmware prevents me doing that. How do I proceed from here?
     
  6. Greg Holloway

    Greg Holloway Administrator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    911
    Likes Received:
    591
    there is a max travel gcode setting in the config.g file

    is this your first 3d printer?
     

Share This Page