One layer is black in PrusaSlicer
 

One layer is black in PrusaSlicer  

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Sgt Freshmeat
(@sgt-freshmeat)
Active Member

Hi folks,

I'm fairly new to this world, so please be patient 🙂

I sliced several stl's together to plan the print the most efficiant way and started printing yesterday. During the print a crash was detected (y-axis), but I couldn't find a real reason. There was a short filament end bend sidewards, but as he was resuming, he was going over this without any problems. (I paused the rpint, cut it off and resumed). The print turned out ok, there were around 5 cm perimter missing.

I continued the print today with the mirrored part of that leg I printed yesterday. Same crash, same height, same outcome.

Both parts missing the perimeter on more or less the same point, print orientation was not the same

So I checked the layers in PrusaSclicer and I found a black layer (layer 80).

Layer 79: Layer 79

Layer 80: Layer 80

Layer 81: Layer 81

 

So what the hell happened? Is that something regarding to the stl-files? And how can I prevent this. In general I'm not checking all layers (and it was not necessary), if there's a black sheep. All other prints were fine so far. 

The stl-files I created by myself using a step-file (not mine) in shapr3D, may did I something wrong?

 

Thanks in advance 🙂

Posted : 08/05/2021 7:39 pm
Swiss_Cheese
(@swiss_cheese)
Prominent Member

Please save your project as a .3mf file Zip it up and use the Add Media button in the upper corner of the reply window to post it here. the .3mf project file will have a copy of the model in it and all the settings as they pertain to the model, this will allow us to see what it is your trying to do and make suggestions, or changes to the project relative your goal, it's the fastest way for us to help.

 

Good Luck

 

Swiss_Cheese

The Filament Whisperer...
Posted : 09/05/2021 2:33 am
Sgt Freshmeat
(@sgt-freshmeat)
Active Member

So, as the images didn't work, I'll try to implement those again: In between I recognized, that I can see the black layer only, if I have the travel enabled. otherwise it's not displayed. The next printed part was without any problems (there're also nothign displayed in Slicer).

printed parts:

 

 

layer 79:

 

layer 80:

 

layer 81:

 

@swiss_cheese
Here is the zipped 3mf-file: Ipad_stand_modified_layer 80 black

 

Thanks 🙂

Posted : 09/05/2021 9:18 am
Robin
(@robin)
Estimable Member

This is wired. I don't know what exactly happens, but the problem is caused by the supports. Some strange support is generated on top of the big part. The over all number of layers does seem off as well when supports are generated: The big part is 15mm in height, using a layer height of 0.2 mm you should end up with 75 layers, which is what happens, when you disable supports and slice your project. I'd recommend to remove the parts which need supports and slice and print them separately. If the problem persists with the supported parts: Try to use support enforcer instead of auto generated supports...

Also: I don't think the parts need support at all. I'd print them without.

This post was modified 1 month ago by Robin
If at first you don't succeed, skydiving is not for you....
Posted : 09/05/2021 10:19 am
Robin
(@robin)
Estimable Member

If you look at the parts in detail, you'll see, that they are especially designed to avoid the need of supports. For example, there are rectangular bridges in the holes of the big part where the diameter is reduced:

If at first you don't succeed, skydiving is not for you....
Posted : 09/05/2021 10:29 am
Sgt Freshmeat
(@sgt-freshmeat)
Active Member

@robin

thanks 🙂 If I remove the supports then the black layer indeed didn't appear. Even tho he was not generating supports on top of the parts (at least not in real). All the supports seem to be on the right place. But I see the layer amount change. So this is then a bug in the software.

I'm printing with PETG and bridging isn't the best with that, so I thought I should maybe enable the supports. As I'm new to that, I dont know how to evaluate if supports are needed or not. I trusted the program 😉 So rectilinear bridges are not required to be supported? What kind of bridges then need support?
On the next printed part are some roundings, he printed them with supports and in the end It was unecessary and truned out kinda ugly, I guess. But as this is a functional print, I just sanded the edges and I can live with that. I also will not print the crashed-parts again, they turned out okay. I would like to be sure that problems doesn't persist in the next prints or if I should check the travel path on every print.

This post was modified 1 month ago by Sgt Freshmeat
Posted : 09/05/2021 10:41 am
Neophyl
(@neophyl)
Famed Member

Robin, when I open your project and slice it doesnt have any strange issues with any of the layers.  It looks perfectly normal to me.

However I've seen this sometimes before where opening a saved project actually fixes a model issue as the save to 3mf process can sometimes repair things due to the format of the 3mf file.

Could you zip up the original large part, I'd be interested to see it without it being modified by PS.

Anyway from your pictures of the preview and the actual print I have a theory.  Notice the inconsistency in your print corresponding to your problem layer, where it looks like its missing bits in the perimeter. I think there's a problem with the model and Slicer is missing a complete layer for it.  That's why its adding in supports, for the layers/parts above.  With your default support settings of 0.1 the supports will weld themselves to the upper and lower part but I think that part will split along that layer if its stressed.  

I'd bet if you turned supports off completely and sliced you would get the warning about a missing layer.  Given that the error doesnt seem to be there in your saved one you could also just try loading that one in, or using the built in fix through netfabb option if you are on windows 10

Posted : 09/05/2021 11:10 am
Sgt Freshmeat
(@sgt-freshmeat)
Active Member

@neophyl

No, if I turn off the supports there‘s no missing layer. I tried from several files now and it’s everyone the same, if I put more stl‘s together (cannot upload now, will do that later). 

you need to turn on the travel option to get the error! Without it will not show the problem, but it will encounter the crash while printing. 

Posted : 09/05/2021 11:36 am
Neophyl
(@neophyl)
Famed Member

Sorry Sgt, you are correct, I missed the part about travel paths needing to be turned on in the preview.  

Its normal for support layers to not be tied to print layers in slicer.  This means if you enable support you will often see the number of layers changing.  This is because of the support layers.  Your object layers may go up 0.2 each time but the support could go up a lot less, or more.  Depends on the model.

With this model, for some reason at that layer its adding a tiny bit of support interface in mid air.  This means its not printing any object extrusions on that layer, zipping over to the support and then zipping back to print the next object layer.

you can see it in this screen cap.  There is nothing on the model to cause it but Slicer does weird things like this with supports.   As this project doesnt require ANY supports for any parts you have on the build plate just turn supports off entirely.

Oh and those areas on your print where it looks like theres gaps, then those probably are gaps, caused by the ironing (they are on the same layer it looks like).  Ironing can cause temporary extruder clogs which leads to missing parts on areas after the ironing happens. 

Posted : 09/05/2021 1:26 pm
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(@)
Illustrious Member

Layer 80 has a tool position marker turned on; no clue how to do that, but here's what it looks like (white arrow pointer): I don't see any missing layers.

[x] Tool Marker ...

This post was modified 1 month ago by --
Posted : 09/05/2021 3:06 pm
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(@)
Illustrious Member

An anomalous support fringe is being thrown in on layer 80 ...

Posted : 09/05/2021 3:30 pm
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(@)
Illustrious Member

I just moved the arm a bit and rotated it 10 degrees and found that many layers now turn black with support anomalies. Turning support off eliminates all the weirdness.

This post was modified 1 month ago by --
Posted : 09/05/2021 3:37 pm
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(@)
Illustrious Member

@neophyl

You have to love parallel processing 🙂 

What time zone are you in? I'm MST/DST.  Your post showed up just after I posted mine, but was placed before mine in the thread. And I had only downloaded the 3mf file a few minutes earlier. 

This post was modified 1 month ago by --
Posted : 09/05/2021 3:44 pm
Robin
(@robin)
Estimable Member

Something seems to be wrong with the forum's timestamps. I got an email that Sgt Freshmeat replied in this thread at 11:41 (shortly after my second post) but there is no post in the thread. When I listed the subforum ( via https://forum.prusaprinters.org/forum/prusaslicer/  ) it showed last post by anonymous 53 years ago for this thread... So much for wired stuff happening... :))

If at first you don't succeed, skydiving is not for you....
Posted : 09/05/2021 3:54 pm
Neophyl
(@neophyl)
Famed Member

@tim-2

Im in GMT/BST .  The forum has always done weird things from day one.  The anonymous one though is usually when it sits there with a utc timestamp of zero in the database (53 years ago approx), until something updates and it gets processed properly I think.

Posted : 09/05/2021 4:01 pm
Sgt Freshmeat
(@sgt-freshmeat)
Active Member

@robin

Really weird. I postet on 11:36 am. It is listed and stated in my version. 

so to get a conclusion: PrusaSlicer is calculating weird supports and therefore the printer is crashing. How can I prevent this in future? Should I check every print now? I guess I cannot print without supports in the future 😀

btw: at which angle are you enabling supports? As I am new to this I have no idea to analyze the stl‘s for supports. 
But today I printed a part, which should have supports, without and it went very nice. So when do I use supports? 

Posted : 09/05/2021 4:32 pm
Swiss_Cheese
(@swiss_cheese)
Prominent Member

@sgt-freshmeat

 

I didn't get any obvious anomalies when I sliced this, however I recently printed a drone frame that I downloaded from thingiverse while trying to help someone else and it exhibited this type of behavior, that model had many problems, open edges etc, and slicer would slice it differently every time I clicked the slice button. it would also change the resolution of the model until I fixed it.

 

Another thing, while I love the show travel feature, its a great reference when your trying to steer the print head where you want it to go.  it is very buggy I have had several occasions when it's use has caused the lower half of models I knew were good to disappear, it would however still display the path, this has been going on since 2.3 was released. I've also had several occasions when it would make every other layer disappear.

 

my recommendation: check your model .stl thoroughly errors.

 

Good Luck, I hope this helps.

 

Swiss_Cheese

The Filament Whisperer...
Posted : 09/05/2021 6:01 pm
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(@)
Illustrious Member

@sgt-freshmeat

As for how to know when supports are needed: it is very easy.

In Print settings, enable Detect Bridging Perimeters. Slice the part. Scroll around looking upwards for any dark blue spots on your part. You can also scroll down through the layers looking for the bridge color.

Here's an example of a part sliced at 0.05 mm and 0.30 mm using the default 55 degree angle (a conservative setting)...

 

This post was modified 1 month ago by --
Posted : 09/05/2021 6:16 pm
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(@)
Illustrious Member

@swiss_cheese

I looked at his model posted here that is having the support problem and got it to show many "empty" layers. Except they weren't empty. Just had spurious support flakes that were being printed. So the layer looked blank, but wasn't: there really was one tiny bit of support pattern somewhere in the field. 

But before I started looking for slicer faults, I did do a reasonable check of the parts for any catchable errors in NetFabb and in 3D-Builder (which seems to catch and fix a lot more than NetFabb can. His part here doesn't have anything wrong with it. I even loaded the stl into CAD and examined end points for far flung single point vertices: none.

Posted : 09/05/2021 6:24 pm
Neophyl
(@neophyl)
Famed Member

Same here, I took it into Blender and except for some thin faces on the bottom nowhere near that extraneous support its one of the cleanest models I've seen.  I will be glad when 2.4 is out as they have been looking at support in that.  Not that I'm expecting it to have got rid of all the weird little quirks.

As for support, I very rarely use anything auto for support any more.  I use pretty much the same technique as Tim, I slice, look for the obvious overhang spots with the colour coding and then I use the paint on enforcers generally to define support for those areas.  I also make the area painted small and then slice and only then make it a bit bigger if I think I needs a bit more support.  

I know with my setup I can generally print up to a 65 degree overhang at 0.2mm layer height without a problem.  One other thing I often do is once support has been painted on to then turn overhang detection off so that PS wont use the thicker extrusion for those perimeters that it does when treating them as overhang.  That's one thing thats supposed to be in 2.4 too, the option to disable the wider extrusion width for overhangs, but we will have to wait and see.

Posted : 09/05/2021 6:33 pm
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