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Solved Y-axis Auto Level Problem

Discussion in 'Troubleshooting' started by usafitz, Apr 29, 2017.

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  1. usafitz

    usafitz Member

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    Hey all, thanks in advance for your thoughts.

    One of my printers is an R1 with rod upgrades. The bed holder was worn out, so I replaced the plastic pieces with new prints from my R1+. After I replaced the bed, the auto-leveling doesn't center. When I hit print, it'll home everything, but when it goes to center before it starts the auto-level, it goes a couple inches past the R printed on the bed. When it hits points 7, 8, and 9 of the auto-level, it'll hit the motor stops and crunch a bit. Then the print will start.

    I'm not worried about the prints at all. After it starts printing, it turns out fine, but I'd like to figure out how to make it center during auto-level in the middle of the R printed on the bed. Is there any way I can do this?

    thanks again for your help.

    [​IMG]

     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The printer only knows a few things.
    One is the size of the bed. This is a hard fact :)
    The other is the HOME location for each axis.
    This is via the HOME switch for that axis.

    So the FAR end of each axis (the end away from HOME) is all math.

    "The bed is AA x BB and I am at home so X HOME + AA is my limit. Y HOME + BB is my limit " etc..

    If it is grinding then either:
    1) the size of the printer is incorrectly defined in the firmware (let's mark that one "unlikely")
    2) something is preventing it from traveling the entire distance.

    In your case I am betting the latter. Something has restricted the Y from reaching the full distance of travel...not by much though.
     
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  3. usafitz

    usafitz Member

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    Thank you for the help. It's an interesting train of thought. The firmware has not changed, so in theory, it should think the bed was the same size as before I changed it.

    For the travel distance, since it starts the auto-level higher up (above the R), it's hitting the physical limitation of travel; there's nothing preventing travel except the end of travel.

    I am going to go check out the firmware and see if I can find something. I'll let you know what I find.
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If the home (start position) of Y changed that could do it. The home switches are physical inputs to the Arduino.
    The extents of the travel are defined as math :)
    So if X is defined as a size of 228 mm then the extent is HOME + 228, Y extent is HOME + 254 mm, etc. (just to assume some numbers)

    My suspicion is that you have either moved the HOME or limited the axis travel slightly (wire bundle in the way, etc) Something physical.
    The cheap solution is to redefine the MAX extent :)

    EDIT: one other thing that would be bad is if the steps/mm changed for an axis then not only would the bed move less/further than intended, but your printing will be wrong since it can't correctly position that axis. That is all mechanically determined (type of stepper, size of cogs/gears, etc.) Sure there is a number in the firmware but not one you likely adjusted and it is based on the physical characteristics of the drive for each axis
     
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  5. usafitz

    usafitz Member

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    Mark, my ignorance would have taken me down an unsolvable path... Neither of the categories you suggested in your first reply were the problem; your last reply nailed it!

    Check it out, when I printed new bed holders, I also changed the position of the switch (original was the hole behind the switch)... just so happens it's the exact distance as my problem.

    Thank you for your quick replies... now back to printing. :)

    [​IMG]
     
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  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Glad you got it sorted :)
    There was not enough detail to sort out exactly what changed so I wanted to just shot-gun everything that might affect that.
     
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