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Zits on curved surfaces, crazy toolpath


Brilliant_Name
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Posted · Zits on curved surfaces, crazy toolpath

Hi!

Using Cura 3.6 with an Ender 3, calibrated extruder, flow and retraction. My filament diameter is consistent.

I have issues with zits on the walls. The effect is at it's worst with thin walls.

The results are very repeatable, the zits are always in the same places. 

From what I was able to deduct,  it is related to Cura toolpath generation, jumping all over the place.

 

First example is a simple cookie cutter, double thickness walls. The part on top is just a cutout of the same model, printed with the same setting. Much better, but without the interior, there was a lot less jumping around. Not even close to good.

 

Decided to try Slic3r, and lo and behold, day and night difference.

I've made a test model, just an double walled oval and some pins. 

Bottom is Cura.

 

I tried coasting, different z seam settings, nothing worked.

 

So, before I give up on Cura, any ideas?

 

20181120_203827.jpg

20181120_204001.jpg

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Posted · Zits on curved surfaces, crazy toolpath

Over-retraction is a common source of zits because it sucks air into the nozzle. You're using 5.5 mm which does seem rather a lot for a short bowden. I run a bowden printer and only use 4.5mm and get very good retractions. Also, I would have thought that coasting is going to make it worse.

The inner wall speed in your profile is very high. For good quality, I tend to use the same speed (and line width) for inner and outer walls so that the extruder pressure doesn't need to change. This can help reduce the bump at the z-seam.

 

It's generally worth enabling the wall print order optimization.

 

Hope this helps.

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    Posted · Zits on curved surfaces, crazy toolpath
    Just now, smartavionics said:

    Over-retraction is a common source of zits because it sucks air into the nozzle. You're using 5.5 mm which does seem rather a lot for a short bowden. I run a bowden printer and only use 4.5mm and get very good retractions. Also, I would have thought that coasting is going to make it worse.

    The inner wall speed in your profile is very high. For good quality, I tend to use the same speed (and line width) for inner and outer walls so that the extruder pressure doesn't need to change. This can help reduce the bump at the z-seam.

     

    It's generally worth enabling the wall print order optimization.

     

    Hope this helps.

     

    With regards to retraction, I can get by with 3.5 mm but I have upped it after adding Retraction extra prime to fix the underextrusion on layer start/after long travels.

    In my testing coasting didn't affect prints so I left it on.

     

    I'll see if the inner wall speed changes things.

     

    The photos attached show the same model printed with the same settings. The upper one I just cut in Meshmixer. The difference is staggering. I'm guessing the lack of inner model made for much less travel and a better toolpath.

    20181120_204001.jpg

    20181120_203827.jpg

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    Posted · Zits on curved surfaces, crazy toolpath

    Tried Simplify3D, and the differences are evident. I've been using Cura for a month, tweaking and tuning, I got this result after a couple of hours with S3D.

    I still have to properly tune it, but at least it's not generating garbage like Cura.

    I do like the Cura interface more and would like to use it, but with results like these it's just pointless.

     

    If someone has ideas, please chime in.

    Cura is the bottom one.

     

     

     

    20181121_183833.thumb.jpg.92b5f95377891510b735885a6a0d1d3d.jpg20181121_183944.thumb.jpg.37d0f97f1d7743029065370632fe328c.jpg20181121_165751.thumb.jpg.dd9388cfd1049719724ea8c8de537f66.jpg20181121_165717.thumb.jpg.6e202d5b50b26f8d5c5a74321e8d558d.jpg

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    Posted · Zits on curved surfaces, crazy toolpath

    A bunch of Cura prints.

    The zits are always in the same place, even though I changed a lot of settings. So it's not a random mechanical slop or filament issue.

    Other slicers don't exhibit any of the artifacts.

     

    Settings changed, from top to bottom:

    18. combing off

    16. reset to draft, extra prime amount to 0.4

    13. z seam alignment to sharpest

    12. z seam alignment to shortest

     

    Any input would be very welcome.

    20181121_190137.thumb.jpg.34984eb115a684aa11589c80c10d5c71.jpgI

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    Posted · Zits on curved surfaces, crazy toolpath

    Set the z-seam to user defined and specify a non-zero value for at least one of x or y to force the seam to be in one place. If the zits pattern changes then you know that the problem is likely to be related to layer change/retraction.

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    Posted · Zits on curved surfaces, crazy toolpath
    2 hours ago, smartavionics said:

    Set the z-seam to user defined and specify a non-zero value for at least one of x or y to force the seam to be in one place. If the zits pattern changes then you know that the problem is likely to be related to layer change/retraction.

     

    Thanks for the tip. I either forgot to test or missed the option. 

    The results are good, zits on the sides of the oval are mostly gone, but others are still present and even in the same places.

     

    I've also attached the Cura travels, for both Z seam settings and I'm even more confused. They are not that different and nothing weird on the sides of the oval that would explain the difference in prints.

     

     

    Top: Simplify3D

    Middle: Cura Z seam alignment set to user defined

    Bottom: Cura Z seam alihnment set to shortest

    20181121_231952.thumb.jpg.4505e63ce3dc590db8428ae53861ac44.jpg

    20181121_232140.thumb.jpg.1df7e95fd6912c9ce83b8b105da069f2.jpg

    20181121_232026.jpg

    cura-z-seam-alignment-travels.jpg

    cura-z-seam-alignment-travels-shortest.jpg

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    Posted · Zits on curved surfaces, crazy toolpath

    Smartavionics?

     

    Any ideas what could be the cause?

    It would seem to me that I should be able to get rid of the zits as they are very repeatable (even tried another filament, just to confirm).

    I'm open to any suggestions for testing or debugging.

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    Posted · Zits on curved surfaces, crazy toolpath

    Sorry, I don't have any ideas but let's think about this. If you are not over-retracting and sucking in air then it must be something that is causing the extrusion rate to change. Looking at the gcode there's nothing obvious that's doing that.

     

    If you take away the pins and just have the round object do you still get any zits?

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    Posted · Zits on curved surfaces, crazy toolpath
    2 minutes ago, smartavionics said:

    Sorry, I don't have any ideas but let's think about this. If you are not over-retracting and sucking in air then it must be something that is causing the extrusion rate to change. Looking at the gcode there's nothing obvious that's doing that.

     

    If you take away the pins and just have the round object do you still get any zits?

     

    I lowered my retraction to 3.5mm from the 5mm, no change. 3.5mm is the minimum for my bowden setup.

     

    I'll try the oval again after my current print is done.

    I'm printing another cookie cutter and with user defined z seam it's coming out much better, but still, the zits show.

     

     

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    Posted · Zits on curved surfaces, crazy toolpath
    50 minutes ago, smartavionics said:

    If you take away the pins and just have the round object do you still get any zits?

     

    Just printed the oval without the pins and I still get zits, though less of them.

    Printed two of them, back to back to confirm that they would be in the same place, and sure enough, same places.

     

     

    20181122_192955.thumb.jpg.f5fccab7094970abc28ebfc8ebe25217.jpg20181122_193042.thumb.jpg.119f3a2fd6b3db3dffc29776b93a8c0f.jpg

     

     

    Having objects inside makes it much worse. Here's the cookie cutter, with z-seam alignment set to user.

    I've also attached the 3mf file.

    20181122_192352.thumb.jpg.f9facb51a9137d94b1c73273d34cb508.jpg20181122_192332.thumb.jpg.f0397efde669a9e2e9b0e3c55e466aac.jpg20181122_192342.thumb.jpg.8190d502d3b1d7734f608b20c051b9c9.jpg

    20181122_192422.thumb.jpg.69db66611acdb18b972db3db75df42e1.jpg

    20181122_192422.jpg

    20181122_192352.jpg

    20181122_192342.jpg

    20181122_192332.jpg

    CE3_cc-poop-emoji.3mf

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    Posted · Zits on curved surfaces, crazy toolpath

    In the mean time I changed my firmware to Klipper, but the issue persist and more artifacts.

    I also noticed that the Cura print will slow down in on outer walls producing the vertical lines.

     

    The Cura gcode is also 50% larger.

     

    S3D on the right, Cura on the left. S3d print was also 40% faster.

    20181125_164300.thumb.jpg.3f32192e17d69b3fbc82ff8eae2c6aa6.jpg20181125_164409.thumb.jpg.6894685b41361b9bdcec9d7b57624a37.jpg

     

     

    Cura on the bottom, S3D top.

    20181125_164127.thumb.jpg.74b5ce07d7170a75d04a5eb76cc0f1ae.jpg

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    Posted · Zits on curved surfaces, crazy toolpath

    Intenta desactivar control de aceleración y control de jerk, ami me funciono. Tenia problemas con el codigo M204 y M205 que aparece en el codigo que genera CURA

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    Posted (edited) · Zits on curved surfaces, crazy toolpath
    On 11/25/2018 at 7:51 AM, Brilliant_Name said:

    S3D on the right, Cura on the left. S3d print was also 40% faster.

    Was this labeled correctly? The one on the left looks a lot better than the one on the right.

     

    (Just realized this was a necro'd thread... sorry to add to it).

    Edited by johnse
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    Posted · Zits on curved surfaces, crazy toolpath

    After more than 20 of the retraction test prints, I disabled the setting "Compensate Wall Overlaps", then set z-seam to shortest, and it completely fixed the zit problem. 

     

    -camper

    IMG_3823.JPG

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    Posted · Zits on curved surfaces, crazy toolpath

    I just want to say that you are a life saver. I have been playing with all the same settings early in this thread to no avail. Your last comment regarding compensate wall overlaps and then set z-seam to shortest did the trick for me as well!

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    Posted (edited) · Zits on curved surfaces, crazy toolpath

    Hey @campervd thank you for your tip and @Brilliant_Name for your vigorous efforts. I had the same problem (very consistent zits), were printing the 3DBenchy over and over again (at lest a part of it) you saved me a ton of filaments 👍 thank you!

    Edited by eoyilmaz
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    Posted · Zits on curved surfaces, crazy toolpath

    It seems that setting the Z Seam to Shortest helped in removing the spiky Zits. But to reach the smoothest outer wall on curvy surfaces, the real gain was on setting the Outer Wall Speed to 1/4 of the Print Speed. And If you want to keep the total print duration the same you can also increase the Print Speed to compensate for the slower Outer Wall Speed. So changed my normal settings to:

     

    Print Speed: 75 mm/s (from 50 mm/s)

    Infill Speed: 75 mm/s (from 50 mm/s)

    Wall Speed: 12.5 mm/s (from 25 mm/s)

    Outer Wall Speed: 12.5 mm/s (from 25 mm/s)

    Inner Wall Speed: 25 mm/s

    Travel Speed: 187.5 mm/s (from 150 mm/s)

     

    The total print time was around the same.

     

    Also, I tried using Slic3r. Man, it printed faster and absolutely better. The outer walls were excellent. Will keep using it for a while.

    Cura.jpg

    Slic3r.jpg

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    Posted (edited) · Zits on curved surfaces, crazy toolpath

    According to the comments on this YouTube video:

     

     

    It seems that if "Compensate Wall Overlaps" option is enabled Cura will totally ignore the "Maximum Resolution" setting and it will generate a ton of 0.01 mm moves. You see, when the "Maximum Resolution" setting is ignored the control card catch up the printing speed and the printer needs to stop or slow down a little bit.

     

    Also, I followed the suggestions on this video:

     

    It helped a lot. But in my previous post I showed the result out of his suggestions (changing baud speed, increasing buffer in Marlin and slowing outer wall speed). You see, that Cura is still behind Slic3r in quality.

     

    What interesting is that, I remember the first time I printed the 3DBenchy, it was excellent. Then I remembered that I printed it from the SDCard not from OctoPrint.

     

    So, it really seems that the source of my problems with my 3DBenchy prints are all about the high detail that the control card can not keep up with. And thinking that the same file resulted a smaller G-Code with Slic3r also makes me think that Slic3r is cleverly removing details. Here they are talking some kind of clever simplification that will keep the curvines of the edges while simplifying the data: https://github.com/slic3r/Slic3r/issues/3888#issuecomment-298214369

     

    Now I updated the Firmware reintroduced the SDCard functionality, will update the firmware and print the same file from SDCard. I'll report back my findings.

    Edited by eoyilmaz
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    Posted · Zits on curved surfaces, crazy toolpath

    Ookay my problems are solved:

     

    So the main problem was, as I stated in my previous post, the "Compensate Wall Overlaps". Because with this option my "Max Resolution" setting was ineffective. What made it even confusing was that in the mean time I thought my "Max Resolution" setting was too big and reduced it from 0.5mm to 0.01 mm thinking that I was eating a lot of detail with a huge dimension like 0.5mm. So after disabling the "Compensate Wall Overlaps" setting as suggested by @campervd, I didn't see to much improvement because my "Max Resolution" setting was still around 0.01 mm.

     

    So the photo labelled as  Before has the Compensate Wall Overlaps setting on with normal printing speeds. The one labelled After my settings were:

     

    Z Seam Alignment: Shortest

    Compensate Wall Overlaps: Off

    Maximum Resolution: 0.5 mm

    Maximum Travel Resolution: 0.05 mm

    Maximum Deviation: 0.05 mm

    Print Speed: 75 mm/s

    Infill Speed: 75 mm/s

    Outer Wall Speed: 12.5 mm/s

    Inner Wall Speed: 25 mm/s

    Top/Bottom Speed: 37.5 mm/s

    Travel Speed: 187.5 mm/s

    Initial Layer Speed: 20 mm/s

     

    And all my problems seems to be solved. Thanks for everybody in this topic. I tried to share everything I learned meanwhile. So cheers!

    before.jpg

    after.jpg

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    Posted (edited) · Zits on curved surfaces, crazy toolpath

    Hey guys,

     

    Along with the Cura settings I mentioned above, I've also added a 3D printed motor mount for the Z Stepper and adjusted the motor placement and tightened some bolts etc. aaand I've probably printed the best 3DBenchy I've ever printed. The Z stripes are reduced a lot (still see some though). So I'm happy. "Darısı başınıza..."

     

    Cheers,

    _A7R2045_lores.jpg

    _A7R2046_lores.jpg

    Edited by eoyilmaz
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    Posted · Zits on curved surfaces, crazy toolpath

    Not everything is software related, but with the combination of both you reached a nice result. 👍

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    Posted · Zits on curved surfaces, crazy toolpath

    It seems there is a bug with Cura 4.7.1: https://github.com/Ultimaker/Cura/issues/8321

     

    People say that with 4.6.2 there were no such problem.

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