Prints stretched in the Z axis

Discussion in 'Calibration, Help, and Troubleshooting' started by fpex, Nov 24, 2016.

  1. fpex

    fpex Well-Known Member

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    I have been suffering from this issue very often.
    I tried changing steps and failsafe. I printed after cubes in order to calibrate the printer. But eventually the printer decides that it needs dos stretch.

    I do not know what to do any longer?

    Any suggestion? Change electronics? Change config? Sell the printer? Dismount the printer keep some parts throw others?

    I just lost a huge print because it had decided that circles had to turn in ellipse .. and I mean ellipse (1,8cm x 2.5 cm) of huge error (30%)

    UPDATE: I have been moving the z axis up and down and measured and I observe an error below 2% when moving. The GCODE in S3D are fine, what is going on?
     
    #1 fpex, Nov 24, 2016
    Last edited: Nov 24, 2016
  2. Jasons_BigBox

    Jasons_BigBox Well-Known Member

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    Is the z movement more or less than you want?
     
  3. Jasons_BigBox

    Jasons_BigBox Well-Known Member

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  4. fpex

    fpex Well-Known Member

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    Interesting thread. I will need to check if I have overheating issues as well causing this. Because my problem is exactly the same!

    UPDATE: Actually my problem is not skipping steps, I notice that after few layers the z axis jumps and accelerate moving up! This week end I will check voltages and see if that helps something. Otherwise, I might also try changing electronics and see.
     
    #4 fpex, Nov 24, 2016
    Last edited: Nov 25, 2016
  5. Stefan

    Stefan Well-Known Member

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    maybe faulty stepper driver? e.g xchange z and y, adjust Voltage and check if the error in now on y
     
  6. Jasons_BigBox

    Jasons_BigBox Well-Known Member

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    Moving faster!

    That's a new one for me. I found a high stepper voltage was causing stuttering if the steppers (both in sync). They did jump back and forwards but didn't rotate more than about 45degrees. I reduced mine significantly and haven't had that problem since.
     
  7. fpex

    fpex Well-Known Member

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    I will need to test, but it would also be a problem on the other two axis of moving less. I need to rerun all calibration but bigger ones to see.

    I swapped the driver from E0 and Z, since I never use the bowden extruder actually. Readjusted all voltages an enow I will run large calibration prints and check dimensions on X and circular movements and will see.

    I did find the Z driver was at somewhat too high voltage (before switching drivers).

    BTW anybody here can give tips to use the 88xx drivers ? Since I am ding all this it might be worth putting them in also
     
    #7 fpex, Nov 26, 2016
    Last edited: Nov 26, 2016
  8. fpex

    fpex Well-Known Member

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    I changed driver, restore failsafe, readjusted all voltage and printer a big test element with large sides and holes. I got again the print with less than 2% max error. Bah!
    I have this weird feeling that it is the electronics and randomly decides to go nuts.
     
  9. Stefan

    Stefan Well-Known Member

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    hmm, looks like its not the driver then.... and I have no other idea, sorry.

    I have a 8825 on y for some time now, as far as I remember Iinstalled it because of noice... and it may be more quite now.
    https://goo.gl/photos/F88oFTyrqKj9TJDGA

    But I did not adjusted the voltage so I had missing step on y, now with adjusted voltage, ( by sound) I did not have any skips.
     
  10. Kanedias

    Kanedias Well-Known Member

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    Only guessing but if it's only on long running prints maybe it's an overheating problem, what about putting heat sinks on the stepper drivers.
     
  11. fpex

    fpex Well-Known Member

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    They already have heatsinks on.
     
  12. fpex

    fpex Well-Known Member

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    The problem is back. Swappign the drivers solved it for a few weeks and now I am runnnig short prints.
    This is frustrating, it makes the BB a piece of junk!
     
  13. elmoret

    elmoret Administrator

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    Perhaps a bad/intermitted connection on the micro stepping jumper or circuit?

    Do you have another controller you could try?
     
  14. fpex

    fpex Well-Known Member

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    Nope. As usuals after one or two failsafe, it prints well again. I tried changing drivers and things like this. I believe that it is the electronics that at time must fails some number crunching. I guess moving to the duet will solve this (I hope).
     
  15. daveyweaver

    daveyweaver Member

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    I am having the same problem it seems, just started doing it. Each print seems to come out a different height. It prints some of the layers the correct height then a section of larger height layers, its very random. Doing my head in. Swapped driver and still did it. Going to try and wipe rumba and reflash.
     
  16. fpex

    fpex Well-Known Member

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    What helped for me was a failsafe
     
  17. daveyweaver

    daveyweaver Member

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    I did that and didn't help. Going to spend some time on it today and see if can work it out.
    Is yours all OK now?
     
  18. Spoon Unit

    Spoon Unit Well-Known Member

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    I think my issue was very similar to this. In the end, what seemed to solve the problem was to remove and replace every connection into the RUMBA. As overheating felt like it could have been an issue, I also at some point moved the hatch fan connection (which points at the RUMBA) from the 5v connection to the 12V connection just above it, resulting in it churning quite a bit more air out. The fan is a 24v fan, so I think this is pretty safe.
     
  19. daveyweaver

    daveyweaver Member

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    Thank you, will give that a go
     
  20. Spoon Unit

    Spoon Unit Well-Known Member

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    I had also chosen to solder the wires for the z-motors together before screwing them in. I snipped that solder out and reverted to a simple twist as @mike01hu felt that possibly the solder could have fractured and created a less than perfect connection. I was actually quite surprised when everything started working again. For me the problem was like Z just started to overshoot each time it moved. I removed a lot of Z-movement by taking out all z-hopping, but that was only ever going to be a short term solution.
     

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