SOLVED Z axis layer drop

Discussion in 'Calibration, Help, and Troubleshooting' started by Max Pinkney, Oct 13, 2016.

  1. Max Pinkney

    Max Pinkney Member

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    I've just started printing the benchy document to calibrate the new printer, however every time I try printing, after the first few layers, the nozzle no longer runs above the print and instead carves through it. I've tried adjusting the initial layer height without success, and it looks like the failure is to do with the steps between each layer drop? Has anyone got any advise?

    Max
     
  2. Jasons_BigBox

    Jasons_BigBox Well-Known Member

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    If you're printing the one on the SD card, pretty much everyone that tried it had problems. Try downloading the 3D model and slicing it yourself.

    If the nozzle is running into the model, check your z-axis is moving the correct amount. Move it down by a known amount using the LCD and measure.

    It could also be over extruding going on, worth checking your filament calibration.
     
  3. PsyVision

    PsyVision Moderator
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    Does the bed move the correct way when you manually control it? I'm wondering if you have wired it correctly.
     
  4. Max Pinkney

    Max Pinkney Member

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    If I move the controller anticlockwise the bed drops, and clockwise it raises. The bed is dropping for each layer during the print, I can get a good 15 minutes in, but it doesn't look like the drop is enough because it's only after a few layers that the nozzle is carving through the previous layers.

    I've just tried exporting a GCode file taken from the STL and now the nozzle is just hitting the bed on the first layer. I've done the filament calibration too, everything checks out. I've just measured the bed drop over a 10mm, using the base as a datum, it went from +26 to +46.
     
  5. PsyVision

    PsyVision Moderator
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    ah! i think it may have been the way I was thinking you meant by dropping. What pitch lead screws do you have and what are your z-steps?
     
  6. Max Pinkney

    Max Pinkney Member

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    Lead screws are 8mm diameter and Zstep/mm are 400.
     
  7. Max Pinkney

    Max Pinkney Member

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    Is that the correct setup for the Z-axis?
     
  8. PsyVision

    PsyVision Moderator
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    Yes, that's correct.

    What did you put your stepper driver voltages at?
     
  9. Max Pinkney

    Max Pinkney Member

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    Is that the Vmax? If so they're set to;

    Vmax X=150
    Vmax Y=150
    Vmax Z=6
    Vmax E=50
     
  10. PsyVision

    PsyVision Moderator
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    No, I mean the voltages you can set by adjusting the pot on the stepper drivers.
     
  11. Max Pinkney

    Max Pinkney Member

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    X = 0.569
    Y = 0.583
    Z = 0.585
    EXT 2 = 0.567
    EXT = 0.575
     
  12. Max Pinkney

    Max Pinkney Member

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    I've just tried printing again and it looks like the bed isn't dropping for each layer. I let it do 4 or 5 and the bed height remained the same throughout.
     
  13. Max Pinkney

    Max Pinkney Member

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    I still have absolutely no idea why the bed is not dropping. It's working when controlled from the LCD and it will move up and down to auto home, but put something on to print and it fails to drop for each successive layer. Please, can someone give me some advice.

    EDIT: There's still a problem because the print head should not be running through the material after a few layers, but the bed is in fact moving. Perhaps it could be confirmed that this is correct; the LCD readout is currently at around 10 on the z axis but the physically measured amount from the original starting height to the current bed height is a drop of around 5mm.
     
    #13 Max Pinkney, Oct 15, 2016
    Last edited: Oct 15, 2016
  14. Dr Jeep

    Dr Jeep Well-Known Member

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    Try a bit higher on the Z voltage take it to 0.6 dead. The driver has to run two motors wired in parallel so a bit more oompf may help.

    If you want to test the best way is home the printer then get a really good datum measurement at a known Z offset. Wind the bed up and down a few times from the control panel and then put the printer back at the same Z offset and check your datum...if it's out then you are skipping steps for sure.
     
  15. Jasons_BigBox

    Jasons_BigBox Well-Known Member

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  16. PsyVision

    PsyVision Moderator
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    Do you have 0.9 or 1.8 degree step motors on your Z? It sounds like it's moving half as much as it should...
     
  17. Max Pinkney

    Max Pinkney Member

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    So i've tried today changing the voltage and comparing an actual measured drop with the LCD measured drop. Setting the potentiometer to 0.464v the LCD measured 9.98mm and the actual bed drop was 5mm. Moving it up to 0.664 the LCD measured drop is 9.98mm and the actual measured drop is 5mm.

    I've just opened up the bottom as well and checked the steppers. Both are 0.9 degree steppers.
     
  18. PsyVision

    PsyVision Moderator
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    The z should be 1.8 according to the manual.
     
  19. Max Pinkney

    Max Pinkney Member

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    That's probably it then. None of the other steppers I was provided are 1.8 degree; all 6 are 0.9. That seems to be the bottom of it, thanks for all your help everyone, will get on to the E3D and see about getting them swapped.
     
  20. PsyVision

    PsyVision Moderator
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    Or up your Z steps...
     
    Max Pinkney likes this.

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