y axis issue

Discussion in 'Calibration, Help, and Troubleshooting' started by Martin Low, Sep 21, 2016.

  1. Martin Low

    Martin Low Member

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    Hi,

    I have an issue with the y axis. Here is what happened on my last print.

    I auto homed and levelled the bed.
    I started a print (the nozzle went to the dump bin at Y=235 as it should then started the print as normal)
    I had to cancel the print due to the filament not feeding and when I did this the nozzle returned to the dump bin y=235 (although this time it stopped 5mm short in the y axis but showed it as the same position as before)
    I fix the filament and start the print again (this time the print starts but at 5mm offset in the y direction from the first time)
    When the print ends it again returns to the dump bin but with the 5mm offset again but still shows y=235

    If I auto home again and manually move to Y=235 then it is correctly over the bin again.

    Anybody have any idea where this offset is coming from?

    I am using,
    BigBox Pro Hybrid (Not dual)
    RC6 Firmware
    Simplify3D
     
  2. Kanedias

    Kanedias Well-Known Member

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    Skipping/missing steps could either be a voltage problem or slipping pulley.
     
  3. Martin Low

    Martin Low Member

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    Thanks I thought about that but it is consistently 5mm off once you start a print each subsequent one prints in exactly the same place
     
  4. Martin Low

    Martin Low Member

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    OK so checked all belts and pulleys and although I did have an issue with one of the belts that has been fixed and it is still not performing correctly.

    Did a bit more investigating.

    At the start of the first print the nozzle goes to the dump bin as it should and starts the print as normal, as soon as the print ends it tries to return to the dump bin but stops short 10mm, if I try and manually move the print head to y=0 it hits the limit switch with 10mm left to travel. During the print I have not intervened at all. Then for subsequent prints without auto homing or switching the printer off it will return to the same point each time which has the offset of 10mm, the only way I can get rid of the offset is to auto home.
     
  5. mike01hu

    mike01hu Well-Known Member

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    Are you using S3D? If so, then it may be the end script that should look something like what follows but note that this is for the Hybrid Dual Mirrored with Alex's additions, so yours may be slightly different. The red text is the important bit and should be there somewhere, so you can play with this:

    ;BigBox Hybrid-Dual Mirrored End Script Begin
    ;relies on M83 (use relative extrusion distances)
    ; lift the head
    G91 ; relative positioning
    G1 Z5 F360 ; move Z axis by 5mm
    G90 ; absolute positioning

    ;move to dock
    T0 ; select extruder 0
    G1 X100 Y200 F3000 ; move to position in front of dock
    G1 X100 Y235 F3000 ; move into dock

    ;purge extruder 0
    T0 ; select extruder 0
    G1 F400
    G1 E25 F400 ; extrude 25mm
    G1 E-14 F4000 ; retract 14mm very fast
    G91 ; relative positioning
    G1 Z-5 F360 ; move Z axis by -5mm to be safe for 4mm homing Z raise
    G90 ; absolute positioning
    M104 S0 T0; turn off extruder 0
    M104 S0 T1; turn off extruder 1
    M84 ; disable steppers
    M106 S0 ; disable cooling fans
    T0 ; select extruder 0
    M190 R30 ; wait for bed to reach 30C
    M140 S0 ; turn off bed
    M117 Print complete
    ;BigBox Hybrid-Dual Mirrored End Script End
     
  6. Martin Low

    Martin Low Member

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    Thanks.
    Here is my end script-

    M117 Print Complete
    G1 X95 Y200 F3000 ; dock position
    G1 X95 Y235 F3000
    M104 S0 ; turn off extruder
    M140 S0 ; turn off bed
    M84 ; disable motors
    M106 S0 ; turn off cooling fan

    Like I say though, the printer moves to y=235 at the beginning of the print and returns to y=235 at the end of the print (according to the LCD display) but it is in a different position physically.
     
  7. mike01hu

    mike01hu Well-Known Member

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    Are you saying that it starts the print 5mm from where it should as this could indicate a start script error? If not, put in the "G90 ; absolute positioning" code at the top of the end script to ensure it refers to the true 0,0 position. Other than that, I cannot see what the problem is. You may want to try restoring the fff file in case there is a glitch in slicing that causes it.
     
    #7 mike01hu, Oct 7, 2016
    Last edited: Oct 7, 2016
  8. Martin Low

    Martin Low Member

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    Thanks again.

    Just in case here is my start script -

    G1 Z10 ; lower bed by 10 mm
    G1 X95 Y200 F3000 ; dock position
    G1 X95 Y235 F3000
    G92 E0 ; reset extrusion distance
    G1 E10 F200 ; extruder priming
    G92 E0 ; reset extrusion distance
    G1 X105 Y235 F3000 ; undock and ready to print
    G1 X105 Y200 F3000
    M117 Print Starting

    I have also tried to print using a couple of different S3D fff profiles from different sources and they both do it.

    It is like the print co-ordinates shift 10mm in the y direction but at what point it does this I don't know. I will try and put up a couple of photos of before and after a print to try and show you what I mean.

    Mike
     
  9. Martin Low

    Martin Low Member

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    Ok here is the position before the print.

    DSC_0404.JPG DSC_0405.JPG

    And here is the position after the print.

    DSC_0406.JPG DSC_0407.JPG

    When the print finishes it does appear to move to the correct place but then jumps forward the 10mm but doesn't register it on the lcd, I think this may be when it happens.
     
  10. Martin Low

    Martin Low Member

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    Ok I think I know what is causing but not sure how to fix it.

    When the printer travels to Y=235 at the end of the print it disables the steppers, but for some reason there seems to be a springiness at the back of the printer, this is causing the carriage to spring forward when the steppers are disables hence why it is not showing up on the lcd.

    Could it be misalignment that is causing this spring effect? It is when I manually push the carriage towards the back just before the wiring comes into contact with the y axis rear bar there is a resistance which causes it to spring forward. I cant see any interference anywhere?
     
  11. mike01hu

    mike01hu Well-Known Member

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    I have the same issue but it does not affect operation as the printer homes before the next job anyway. I think it is a slight misalignment of the Y bars but I have released all screws and re-tightened them but it still happens, so I ignore it!
     
  12. pSimon

    pSimon Member

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    A bit of a guess, but it's not the umbilical for the heads not wanting to bend so tightly? I imagine that could provide a small force away from the back, under the right circumstances.
     
  13. mike01hu

    mike01hu Well-Known Member

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    In my case it's not the umbilical sleeves.
     
  14. Martin Low

    Martin Low Member

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    Likewise there is definitely nothing obvious (including the umbilical) that is causing this. Might just learn to live with it unless someone else can suggest a fix?
     

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