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Why does my print have tiny zebra stripes?

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But only on two sides and only at a certain level?!?

IMG_1984.jpg

The stripes appear on the other side as well. Have not tried rotating yet but will. There is a flat surface out of sight to the left below the side of the boat and it does NOT bear stripes!

Thanks for any pointers!

Will

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It looks like the infill is protruding through the surface!

First I would suggest checking if your X and Y motor belts are taut. If they aren't, there are screws on the sides of your Ultimaker that allow you to move the motors down a bit.

If they are taut, you could try giving it a wider shell thickness, of twice your nozzle size or more. You can also try to reduce the infill speed (in Cura under advanced).

If these didn't fix it, you can reduce the outer shell speed and inner shell speed a bit. It also looks like the printing temperature should be a bit higher but that probably has little to do with your zebra stripes.

Edited by Guest

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Belts seem tight. My shell thickness was 1, which I changed to 1.2 as my nozzle is .4 and Cura did not like the non multiple. Don't think this was the issue as Simplify3D had exactly two shells and same problem.

I will try speeds but first wanted to try the outer - inner. I am running the latest Cura but did not see it as an option so am trying Simplify3D which does support that feature and also the zebra artifact.

What artifact indicates temperature to low? I try to extrude at the lowest possible temperature on my other printer but the U2 seems to run hotter? Is 210 in the ball park for PLA?

Thanks, another swing or two...

Will

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Which stripes? You mean:

1) the diagonal stripes on the upper part of the boat?

2) the vertical stripes on the railng?

3) The strange pattern on the curved hull? (looks like underextrusion maybe)

4) horizontal stripes on hull?

1mm shell is bad - it means it will make 2 .5mm passes and that means pushing .5mm of filament through a .4mm nozzle or 25% extra. This is more than 25% harder to do! This is like twice as hard to do because it is squeezing the filament into a small area between the nozzle shoulder and the part. It takes much more pressure so you need to print at half speed you would typically print at.

Your bottom layer of your boat looks not so good - you should skip the leveling procedure and instead just rotate the 3 leveling screws 1/4 turn counter clockwise looking from below to get the glass closer to the nozzle. This is because you want the bottom layer squished in a little better. Not doing this may be fine for this small part but you run the risk of parts coming off the glass if you don't do this.

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Which stripes?  You mean:

1) the diagonal stripes on the upper part of the boat?

2) the vertical stripes on the railng?

3) The strange pattern on the curved hull? (looks like underextrusion maybe)

4) horizontal stripes on hull?

 

Hmmm...now that you mention it...I would be glad to take advice on any of the above! I can print the same model on my Wanhao Duplicator 4S without any of them! The one that was irking me the most was the first one you mention.

Gotcha on the shell and the first layer.

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I am back after quite a bit more experimentation. I had a filament feed issue that needed correcting. Fairly occasional clicks from the extruder driver are now gone. Not sure if this was a factor but figured it needed correcting.

Having done that I stepped back to some basic Cura settings:

 

  • Normal Setting
  • 15 Second Minimum Layer Time
  • Hotend to 110 After Layer 1

 

All other settings were per the Normal profile.

P1020220.JPG

Very visible zebra stripe still there. Some lines on the outer rail as well. The tops of curves in the ports are a little messy but better than with the 5 second minimum layer time. I would be reasonably happy if it were not for the zebra stripe. Here is the g-Code for the above.

Following the above I did a Normal print will all the same settings but went to four shells and got the following:

P1020234.JPG

Could be really happy with this print but for the lines!!!

I guess the good news is that I can print the little shippy on my Wanhao Duplicator 4S without it looking like a zebra:

P1020229.JPG

Finally...I have also now tried under extruding with no change and am currently printing a slow motion version which should be done shortly. I have also posted a comment on Thingiverse asking for help as this is a very active thing there and I have to assume someone with a U2 has printed it without stripes!

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Thanks for posting about your issues regarding #3DBenchy and the stripes. If you mean the diagonal stripes visible on the vertical walls of the cabin, we believe that they are at result of the infill pattern "touching and bulging" on the perimeter lines.

If you open the expert settings in the Cura slice engine, you will be able to see a value called "Infill overlap (%)". The default value is 15%. Try making this smaller and see if the result changes.

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I printed at 10% overlap and the lines are still evident.   I am not even sure it is worth going lower as the look exactly the same!

This feels like an issue with the Cura slicer except that I get the same thing when I use Simplify3D...which makes it an idiosyncrasy of my particular Ultimaker 2 (as I find it hard to believe no one prints without Zebra effects)?

Edited by Guest

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This was my theory as well - that's why I wanted to see the gcode. But the gcode proves that it is *not* the infill. this is just one frame showing the infill but if you go up layer by layer you will see the infill pattern - if it showed through - would have been less diagonal on this part of benchy - basically it should be vertical. Also in my experience the infill pattern only shows through on transparent PLA or if you have only one outer shell. Two outer shells are plenty:

tug.thumb.PNG.8fa59c0c75b38f9242e856aad25bdba9.PNG

tug.thumb.PNG.8fa59c0c75b38f9242e856aad25bdba9.PNG

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This was my theory as well ...

 

Well then. I have not had the Ultimaker 2 long and may, or may not, see this phenomenon again...but...I would really like to not see it on this test case. Obviously there are at least a couple other folks with the same issue.

Does anyone with a U2 print this cleanly? I would love to hear from someone with a profile that works...or one that does for them and not for me...

Puzzling.

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This problem is bugging me. I pushed my head around for 1 minutes trying to come up with something that would cause this issue - the only things I could come up with are a deep (DEEP!) spiral scratch on one of the thicker rods in the gantry. Or if the rod ended with a bump face instead of a flat end and the case of the printer also had a bump in there and as it rotated the rod would slide sideways. This all seems very unlikely (some hardware issue causing this) but when you printer is powered off some time, try sliding your head left and right and see if you can feel some bumping movement side to side at the same spacing as the lines on benchy.

on to software:

Well I don't think it's the slicer because I looked at much more of the gcode and most of the lines to the left of that arching window are just straight shots. Every 3rd line or so has a point half way but the point doesn't seem to line up with the "zebra pattern".

That leaves the firmware. Marlin. If it happens to you it should happen to everyone. I will try printing benchy with a recent version of Marlin (but that printer is busy for the next 13 hours). I'll even use your exact gcode file!

But please do my "push the head left and right test"!

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I thought of something else that might cause this - if the feeder was doing something weird where it overextruded for a millisecond or so on a regular interval.  This could be the stepper motor moving suddenly and then not moving for a bit - then repeat this for the whole print.  This sounds likely at first - it's just that the bowden tube should be absorbing and averaging out the movements and also the fact that I've never seen this pattern before on any of my prints - but maybe that's because this is an interesting shape - the trapezoidal face.

Edited by Guest

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But please do my "push the head left and right test"!

 

I will do so once one more boat finishes....! I do not expect a difference but this one is at 50% infill.

There is one other user on this thread that has the same problem and the post from the people that designed the little shippy that there might be others as well. So, this is either firmware and it fails for all, or it is a limited edition hardware defect that only impacts a small lot of production printers?

One of the strange things is that it only happens on the cabin...not on the engine box right behind the cabin. Made the infill idea sound logical as there is none there. Which makes the firmware idea more possible.

Puzzling.

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One of the strange things is that it only happens on the cabin...n

The cabin has very flat walls and also they are not parallel to any axis.  Flat walls will highlight tiny tiny errors.  Because this error has such a distinct pattern it is quite visible.  It's possible that any flat wall with this orientation will have the problem.  The rear and front walls I suspect are parallel with the X=0 plane.  Another way to say that: parallel with the left and right walls of the printer.  Another way to say that: The X axis doesn't move at all while printing the front and rear walls of benchy.  One would expect patterns on those walls to be vertical and not diagonal.  So the patterns woudn't be so impressive/unusual there.

If you rotate benchy by 45 degrees the pattern will almost surely change completely.

Edited by Guest

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By the way for doing testing - I recommend the feature "cut off object bottom" under "advanced" "quality". This can save you lots of time when trying different cura options. And no need to print the whole tug. Once the pattern is visible (or missing) you can stop printing.

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By the way for doing testing - I recommend the feature "cut off object bottom" under "advanced" "quality".  This can save you lots of time when trying different cura options.  And no need to print the whole tug.  Once the pattern is visible (or missing) you can stop printing.

 

Excellent idea....! I should have thought of that as I have used that feature in Slic3r. Doop.

Speaking of tests...I did rotate the ship by 90 degrees and the pattern did not move or change...

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Looking back at what I had printed there was one print that did not have the stripes, but had horrible overhangs. I think I printed that one on a 45 degree angle.

WP_20150615_003.thumb.jpg.c9de548fcc1e69741a1b70a3d174d975.jpg

I printed a lot of these and kept no notes (shame on me I know).

WP_20150615_006.thumb.jpg.ca9b7ef9d7775aaa93e096427e8e704f.jpg

I was really hoping to get rid of the artifacts on the hull of the boat so it came out nice and smooth.

WP_20150615_003.thumb.jpg.c9de548fcc1e69741a1b70a3d174d975.jpg

WP_20150615_006.thumb.jpg.ca9b7ef9d7775aaa93e096427e8e704f.jpg

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I was really hoping to get rid of the artifacts on the hull of the boat so it came out nice and smooth.

 

Me as well! That is absolutely amazing as to how exactly our prints match! They look like they might have been done on the High Quality setting? That is where mine showed the lines the worst.

My latest test with raising the percentage of infill is shown below:

IMG_2036.jpg

The left image is 50% infill and the lines are largely gone...but the print doesnt look as good, just not as sharp or something. These are all high speed prints...20mm layer height. The one in the middle is 10% overlap of infill and shell. The one on the right is largely default but for temperature (210 after first layer) and 15 second layer time.

There is clearly something puzzling going on!

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STOP ASSUMING IT'S INFILL.  It's not infill.  If it were infill it would have not been diagonal.  Also people have tried different amounts of infill and it made no difference.

Now looking at the gray/blue/black boats I'm not surprised that different colors act differently.  

Some colors/brands just print much nicer.

Edited by Guest
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