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Solved Possible minor Z-axis issue?

Discussion in 'Troubleshooting' started by MindTorque, Jun 2, 2016.

  1. MindTorque

    MindTorque New Member

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    Greetings and felicitations!

    My new Robo3D arrived yesterday, so far it seems quite impressive although there may be a bit of a Z-axis issue. My first print was the 20mm calibration cube, followed by the Deprime test. There seem to be little peaks on the top corners of cubical objects.; on the 20mm cube the X and Y directions measured 20.00mm across the center of the faces, although the Z-axis measured 20.38mm (also across face center, doesn't count the corner peaks which would bring it to 21.09mm). On the Deprime object these corner protrusions amount to about 0.14mm above the flat.

    TestShot.PNG

    I used the blue sample PLA filament provided with the printer. Given the excellent setup instructions for Cura provided by Mike Kelly on the forum I used that from the very start, using the settings as specified therein apart from M565 being Z-0.9 and having both the cooling fan and the bed heater turned off. The extrusion temperature was 195C and the print speed 50mm/sec.

    Baseline setup:

    After checking for obvious shipping damage out of the box I checked the tightness of the belts and pulleys and verified that the bed cable was out of the way, then leveled the X-axis. Auto bed leveling seemed to indicate a slightly warped bed but I figured it'd likely compensate for that, unsure how typical the results I got are. An M503 let me check the default settings, after which I did the PID autotune via M303 S200 C10 followed by setting the results with M301 P35.17 I3.44 D89.89 and saving them via M500. Then I turned on the hotend and played with the temperature settings a bit until I was satisfied that it was extruding smoothly. After that I did the extruder calibration per Tom's video, finding that the step had to be increased from the stock 723.38 to 784.24 and set it via M92 E784.24 and then saved via M500. I powered everything off for a couple of minutes and upon restart did another M503 to verify that the new settings had persisted to the EEPROM. I then ran the test prints mentioned at the beginning. As I write this it's about 1/3 of the way through printing the nice robo riser feet as found on Thingiverse, which are looking quite good so far.

    Given all of the above, what should I tweak to reach optimum performance of the Robo?

    Thanks :)
     
  2. GAmbrosio

    GAmbrosio Active Member

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    Sample PLA, general consensus is that this material sucks or at least not the best or better to expect great results may be reaching- try a better filament first like Hatchbox PLA PRO, protopasta, etc. then see if it is a problem with the printer.

    Nothing sucks more than to make all the adjustments and it is the filament after all that. :) eliminate the obvious.


    Sent from my iPhone using Tapatalk
     
    #2 GAmbrosio, Jun 2, 2016
    Last edited: Jun 2, 2016
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  3. MindTorque

    MindTorque New Member

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    Thanks for your speedy reply. Since then I've tried a few other things, including the PLA oiler and the top mounted filament spool holder (Thingiverse object 267039) which came out quite nicely with the sample filament - I figured I could get some practice in with this stuff before using any of the full spool of black PLA that I have.

    Although the Z-axis still seems a tad off, so far it doesn't seem to make much difference outside the calibration prints with anything I've tried as yet. In due course I want to use material such as the Taulman nylons after I've gotten used to using the PLA - I'd just like to be sure I've gotten everything correct before buying a bunch of the good stuff; I figure on upgrading to the E3DV6 hotend anyway before trying more challenging material. :)
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Nice Materials and some of my favorite, but you will be learning it after messing with PLA (it is not the same print-wise) :)
    The two materials don't print the same so expect to be adjusting things.
     
  5. MindTorque

    MindTorque New Member

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    Yeah, I presumed as much from having dug through the forums for a week before the printer arrived... I just want to get to the point where I can reliably tell it it's an operator issue, printer issue, or material issue before I complicate things overmuch heh :)
     
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  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Let me know how that works out for you, I still struggle with detecting that specific one.
     
  7. MindTorque

    MindTorque New Member

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    A bit more experimentation with the blue filament using steps derived from squares and circles doesn't seem to show anything shocking insofar as Z-axis height variation, I presume this is within normal tolerances for this sort of printer, although I did notice something else when viewed from a different angle.

    Zheights.PNG

    I'm a little puzzled with the following as indicated in the picture, it doesn't quite seem to fit the description of any of the problems I've read of. I checked the printer again for the usual mechanical issues and there's no sign of electrical problems. Print speed was 40mm/sec and the print temperature was 195C. Am I missing something obvious?

    Zheights2.png
     
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Tolerances are printer dependent to a large extent because of the way the mechanical bits work. There are ideal tolerances and yes... those are probably within that.

    When it comes to artifacts in the print...
    There are 5 basic choices (in no particular order):
    1) It is actually an artifact in the model. Make sure that you run the model through all of the repair facilities (Netfab or Microsoft Azure or the ones included with Simplify3D if yo use that). This is more likely than you might think. Every 3D modeling program has quirks and you must do things in certain ways occasionally to be able to generate a model that is functionally printable. The repair tools will sanity check everything for you.
    2) It is a mechanical issue. If the defect is repeatable across different models with the same general effects in the same general spot then it is likely mechanical in nature. You have to check the following: Belt tension. Belt drive sprockets (they have set screws to mount to the stepper shafts--LocTite is your friend). Stepper motors. Stepper drivers (if they are not working correctly then the stepper will lose steps). The last two are the least likely and will occur everywhere in the print.
    3) It is a communications problem. USB cab drop data if noisy so always use a good quality cable. Worst case add a USB hub between the computer and printer. For best results use an SD card and eliminate the USB cable entirely.
    4) It is a material issue. It is quite possible to get defects in a print simply due to bad filament. The filament is either bad quality/defective or the parameters you are printing it at are not optimal for that filament. EVERY SPOOL can be different and I always run a few small/quick test models with differing parameters to find the best settings for any new spool.
    5) It is a software issue. Your slicer has generated a problem. Try other slicers. (If you are using the free ones... they do have limitations.)
     
    #8 mark tomlinson, Jun 7, 2016
    Last edited: Jun 7, 2016
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  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I will say that given your specific defect in that print...
    3 and 4 are not likely candidates :)
    I just wanted to make the answer as complete as possible.
     
  10. MindTorque

    MindTorque New Member

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    Thanks, I appreciate complete answers. :)

    The artifact appears to have been due to one of the two setscrews on the Y-axis pulley being microscopically
    loose. Our buddy blue Loctite has since been well-applied to all such; it just strikes me as odd that the artifact
    didn't also appear on the opposite face too. Unsurprisingly there were a few minor issues when I switched to
    the other filament, chiefly the extruder temperature needed to change a few degrees to work well.

    Things appear to be working happily enough for me to mark this issue solved, it'd have been quicker if Reality
    hadn't provided a few other unrelated things to attend to in the interim. Thanks again. :)
     
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