Titan Aero Repeating "Pulse" Pattern on Prints

Discussion in 'Titan' started by Mark Wagner, Oct 15, 2018.

  1. Mark Wagner

    Mark Wagner Member

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    Hello All,

    Long time reader, first time posting, so thanks for all of the information that has been gathered here already!

    I have been having a troubling issue with my Ultibots D300VS+ that I think I have finally narrowed down to the Titan Aero extruder having a repeating pulse causing a visible defect in the print surface. If you are interested in the long version of how I came to believe the extruder is the source of the problem, see the link below to the thread on the Duet forum where they helped me narrow it down:

    https://forum.duet3d.com/topic/7135/help-with-strange-diagonal-banding-on-ultibots-d300vs/15

    That thread can be summarized by the picture attached showing the distance between the print defects changing with layer height, leaving everything else the same. My theory is that there must be some repeating mechanical issue in the extruder causing a slight pulse at a constant volume of extrusion and creating the artifacts you see below.

    20181014_140348.jpg
    I have already checked the bearings (although I ordered some new ones to be safe), hob alignment, and gear mesh (including lubricating the gears with some heavy grease) and everything is in order. I have also tried different stepper motors, micro-step settings, temperatures, nozzles, and filaments but the defect remains constant.

    Oh, and before you ask, the extrusion width is within 0.01mm of what is requested by the slicer (Simplify3D) no matter what I ask for, so I am pretty sure it is not an extrusion rate calibration issue.

    If anyone has any ideas about what I should try next, I would greatly appreciate the guidance!

    Happy printing.
     
    #1 Mark Wagner, Oct 15, 2018
    Last edited: Oct 15, 2018
  2. Old_Tafr

    Old_Tafr Well-Known Member

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    Interesting.

    What would be fascinating would be to try the Titan Aero on a totally different printer.

    Another Titan on the same printer would be interesting too.

    The obvious difficulty is that there are so many (too many) different parameters than can be changed on the slicer and a multitude of different possibilities on the printer.

    Even though the printer frame may appear solid I suspect that on it or the Titan or a result of the slicer settings that something somewhere oscillates i.e. vibrates, it could as suggested be pulsing of the filament (heating-- cooling-- printing --- retracting ) some part could be the subject of simple harmonic motion. I suspect that such oscillation isn't visible to the naked eye, and if there is any sound in the range 20 Hz to 20 KHz is too low or drowned out by other noises.

    A flat surface printed in just one plane (axis) would be good too e.g. one layer on the bed, a vertical wall in the X and same in the Y plane. Turning each say 20 or 30 degrees would show if the vibration was in a specific plane, although I suspect it is too complex for that. All this with zero changes to everything else, i.e. same filament, temp, calibrations such as PID, slicer settings and so on.

    I suspect one of the mechanical engineers at E3D could get to the problem very quickly if you can get their attention.

    ----------------------

    Further thoughts.

    Various parts of the printer will have their own frequency at which they oscillate given sufficient stimulation. This in itself will cause some interesting problems with prints or because of a damping effect it will not have any effect. Now picture two parts of the printer having their own simple harmonic oscillation frequency. These two different frequencies will then interact (interfere) this will have a particularly interesting effect e.g. if the two frequencies are slightly different then the effect will be a low frequency varying in amplitude possibly affecting the print.
     
    #2 Old_Tafr, Oct 16, 2018
    Last edited: Oct 16, 2018
    mhe likes this.
  3. Antoine

    Antoine Well-Known Member
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    I don't think I can see the oscillation in the picture (merely moire from the camera) but that might just be my screen. We have never observed the described behaviour from any Titan so would be interested to know what would have caused this issue.
    As Old_Tafr mentioned, there are a lot of parameters that could result in such a pattern showing. Here are my thoughts on the matter:
    • Vibrating heatsink/part cooling fan
    • Worn bushings/bearings/rails on your motion system
    • Resonant frequency of some kind in your carriage/rails/frame
    • Microsteppping/motor steps showing (highly unlikely)
    • Filament idler being too tight and the hobb teeth "showing" in the extrudate due to filament being scored by the hobb
    • Asperity on the pinion or gear (depending on the frequency)
    What might help us troubleshooting this would be knowing the period of the oscillation per filament-in length (NOT extrudate length) and if this period length changes with speed/layer height/material etc...

    Feel free to contact support@e3d-online.com if this proves to be hindering the performance of your printer significantly.
     
  4. Mark Wagner

    Mark Wagner Member

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    Hello all,

    Sorry for the long silence here, but I thought I would share my findings and final satisfaction with this printer in case anyone runs into the same problem.

    I wound up building a new effector to use a standard E3D V6 hot end and built a 9:1 belt reduction drive bowden extruder since I was so certain the extruder was the source of the issue, but low and behold, the exact same surface ripple persisted...

    At this point, I was at the end of my rope and almost gave up but just started really trying to shake stuff around. It wasn't until then that I noticed that the carriages on the printer were flexible enough that I could pretty easily get one of the three wheels to come off of the aluminum extrusion if I pushed in the correct directions. So, I ordered some 12mm knockoff MGN12H rails and carriages and the delta carriages from RobotDigg. With a little bit of cursing and filing, everything fits up pretty great and the first test print shows that the artifact is GONE!!

    So, I put the E3D Titan Aero back on and the result repeated, NO MORE SURFACE RIPPLES! After all of that, it was just an issue with the carriages being a little too flexible and creating what must have been some kind of stick/slip where the wheels are supposed to roll up the towers...

    In the links below, you'll see a picture of the installed rails and the before and after test print comparison. The black print is with the new rails and the blue print is with the old carriages. The horizontal sections you see are my experimenting with different speeds and extrusion rates.

    https://photos.app.goo.gl/zmvhEbGiti6mxVMeA

    https://photos.app.goo.gl/vBSiHC6PRmZ5MGan7

    With that change, this is now hands down the best "consumer" grade printer I have ever been around and would gladly recommend it to anyone that can get their hands on one.

    Any way, happy New Year and happy printing!
     
    Antoine likes this.

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