Settings Based Periodic Under-Extrusion

[BillieRuben 0]

I'm struggling with some settings-based periodic under extrusion. I think it started when I upgraded to 3.6. 

Here is an album of annotated images, describing the issue; 

https://imgur.com/a/XKnfrMR

 

Some notes on the issue: 

• Doesn't happen on brims or skirts, or bridges. Seems to happen on walls, and fill. Which leads me to believe that it's not mechanical, it's settings-based. 

• Happens regardless of machine. These were on both my CR10s5 and Wanhao Duplicator i3 Mini.

• Happens on different filaments (including ones I've used to great success previously)

• Happens regardless of retractions in the area.

• Happens relatively consistently between layers.

 

Anyone got any ideas as to what I might be doing wrong?

 

 

 

[gr5 2,167]

It looks like the problem is only on the bottom layer.  The bottom layer is extremely sensitive to "leveling" or how close the nozzle is to the bed when printing the bottom layer.

 

It looks to me like your extruder is slipping occasionally and that is probably because you are just a little too close to the bed.  Or maybe your extruder is a bit weak.  Or the teeth in the extruder are a bit weak and the filament slips backwards occasionally.  

 

As a test, hold the filament while it is printing the bottom layer and feel for it moving backwards suddenly followed by these underextrusion spots on the bottom layer.  The fix might be to level about 0.05mm farther from the bed.  yes, one half of one tenth of one mm.  0.05mm.  That might be enough.

[BillieRuben 0]

Thanks so much for the reply! 

 

Unfortunately it's not only the first layer. It's all the way through. The last two images are the topmost layer. And watching it print, I can see this issue occuring on every layer right the way through, in the same places on each layer. Note the artifact appears in the layers on the closest corner in images 3&4. 

 

It's definitely not a leveling issue, when I live level the whole bed with a huge brim on a cube it doesn't appear. It doesn't appear on any brims, actually, no matter how wide. Or bridges. Only fill and perimeters. I know leveling can cause a similar effect, but if you zoom in on image 1 you can see it's not squishing the filament, it's simply not extruding it. This is evidenced in the little drippy line that appears instead of a smudgy one from a too-close bed. 

 

And yea, it happens on every layer, so not leveling I'm afraid. :( 

 

The extruder gears seem in good repair on both of the machines I'm working on.

 

:(

[BillieRuben 0]

It looks like I'm not the only one experiencing this issue since updating to Cura 3.6, here's another user on Reddit:

 

 

[Snickerdoodle 0]

15 minutes ago, BillieRuben said:

It looks like I'm not the only one experiencing this issue since updating to Cura 3.6, here's another user on Reddit:

 

 

Yep, that'd be me. I was right next to the printer when it started doing this unusual underextrusion pattern, and I do not believe my printer is at fault for a few key reasons.

• The filament can't slip as I bought a bondtech extruder a few months ago, which has completely erased any issues related to filament grinding and slipping for me
• When I was observing the several layers that started with underextrusion (with some overextrusion around the rest of that perimeter) I heard no clicking from the stepper, so it wasn't missing steps or anything.
• I only saw underextrusion like this when I upgraded to Cura 3.6.0 last night. I was using 3.5.1 before that.
• These lines are clustered together in the exact same spot, and are too consistent for me to consider it random underextrusion.

[WreckMyPrint 0]

Hi, it looks like I may be having the same issue. I originally posted on Reddit here. I am printing on a Monoprice Maker Select v2 (Wanhao Duplicator i3) and I was using the MP version of Cura, which is quite old. I decided to try out Cura 3.6, copied my settings as best I could, and the resulting print had under-extrusion issues that didn't seem to improve when I increased the flow %. Here are some pictures. The first 4 in the gallery are from the Cura 3.6 sliced print. The last two are from the MP version of Cura (I'm not worried about the stringing on this print).

 

More info copied from my Reddit post: 

Quote

Here is what I'm using:

• Printer: Monoprice Maker Select v2 (a.k.a. Wanhao Duplicator i3)
• Filament: 1.75mm PLA White (BAMtack from Amazon)
• Settings: print speed - 60mm/s; print temp - 205; bed temp - 60, layer height - 0.1mm
• Mods: z-brace & bed leveling knobs w/nyloc nuts

I used those settings in both versions, but the MP version of Cura performed much better (aside from the stringing on the back). I attempted to increase the flow % in Cura 3.6 from 100% to 105%, but it didn't seem to make much of a difference.

 

[BillieRuben 0]

Yea I've upgraded my extruder arrangement and got an all metal hot end and I'm still seeing issues. 

[redslifer 2]

I noticed that exact over extrusion only in the top and bottom layers since only cura 3.6, while the perimeters are fine and even the flow is calibrated, since I precisely hit 0.40mm on a 0.4 nozzle.

I couldn't print properly without the print failing because of the nozzle deeping in the print and hitting it.

Downgrading to 3.5.0 solved this issue.. So yeah, something is faulty right there.

 

So please, if some devs will drop into this topic, please consider taking a look.

Edited December 26, 2018 by redslifer

[Smithy 1,144]

You could compare if the "Initial Layer Height" setting is the same for Cura 3.5 vs. 3.6 with the same default profile. I mean I read something that the initial layer height has changed in a recent version. And if it is lower than before then the first layer is squished more into the bed and the resulting line width is wider. Not sure if this could be the root cause, just an idea,

 

 

[redslifer 2]

18 hours ago, Smithy said:

You could compare if the "Initial Layer Height" setting is the same for Cura 3.5 vs. 3.6 with the same default profile. I mean I read something that the initial layer height has changed in a recent version. And if it is lower than before then the first layer is squished more into the bed and the resulting line width is wider. Not sure if this could be the root cause, just an idea,

 

 

I have my own profile with a 0.16 basic line width and 0.20 initial layer line width. But it also happens on top layers so it isn't the problem. The layers are just HUGELY overextruded with cura 3.6

[Smithy 1,144]

26 minutes ago, redslifer said:

But it also happens on top layers so it isn't the problem

 

Ok, then it must be something else.

[BasW 0]

Hi!

 

Has anyone found a solution to this problem?

I am experiencing the same issue (see pictures).

 

I am using a modified Anet A8 printer, printing with 1.75mm PLA, slicing with Cura 3.6.0.

I leveled the bed several times and increased the hot end temperature, but this did not solve the problem.

 

Since the under extrusion is (almost) perfectly periodic, I am thinking that this is a software fault rather than a hardware one.

 

Thanks!

 

[burtoogle 513]

Hello @BasW, please save the Cura project file and attach to this thread. Thanks.

[BasW 0]

Hi!

 

Thanks for your reply!

I downgraded to Cura 3.5.1 and used the exact same settings and the problem is solved.

So I guess the malefactor is the 3.6.0 version..

 

[BasW 0]

I celebrated to early apparently.. Although the prints are getting better, there is still under extrusion at the exact same spot at each triangle (see picture). The file is also attached!

 

Thanks!

Plaintriangle.STL

[BillieRuben 0]

Yea, I'm still struggling with it. Despite an upgrade to an all metal hot end, new extruder arrangement and printing suuuuper slowly. 

 

I've seen a lot of people on the 3d printing subreddit and discord (that I moderate) with this issue, but still no acknowledgement/help here.

 

It doesn't happen in slic3r, but I desperately miss my cura. 

😞

Edited January 29, 2019 by BillieRuben
Added detail

[BasW 0]

Hi @BillieRuben,

 

I am sort of happy that I am not the only one struggling with this issue.

Hopefully an update to the 3.6.0 version of Cura is available soon. I am thinking about using another slicer software too. What are your experiences with Slic3r?

 

Thanks!

[burtoogle 513]

Please could you attach the problematic cura projects and also the gcode that is bad. Without that it's almost impossible to determine what the problem could be. Thanks.

[BillieRuben 0]

It works, does the job, there are a couple of cool infil patterns, but I miss many many settings from cura and cura's useability. 

[BillieRuben 0]

Sure! I'll get some soon.  

[BasW 0]

@smartavionics, I downgraded to Cura 3.5.1, and the problem is less present.

I attached the Cura 3.5.1 gcode and the .stl file I used, since I overwrote the Cura 3.6.0 gcode.

 

Thanks!

 

 

Plaintriangle.STL

CFFFP_Plaintriangle.gcode

[BillieRuben 0]

I've had the issue since upgrading from 3.4.1, myself. 

[burtoogle 513]

Thanks for those files @BasW, you didn't provide the project file so I can only guess at your settings from the gcode file. I see you are using a line width of 0.3mm and a layer height of 0.3mm. In my experience, it's unusual to have a line width so narrow for that layer height. Does the problem still occur when you use a wider line width? If you are using a 0.4mm nozzle, try using a line width of 0.5mm and see what happens.

[BasW 0]

Thanks @smartavionics!

What do you mean by project file?

Indeed, I used a line width of 0.3mm because in a previous print very tiny gaps in the printed grid where visible, so I changed it from 0.4mm to 0.3mm. 

I will try to increase this value!

 

 

[BasW 0]

@smartavionics

I tried the 0.5mm line width using Cura 3.5.1.

As seen in the picture, the under extrusion periodic profile is exactly the same as before (I was too late to take a picture of the first layer, so the picture is of the third layer).

I added the project file and gcode. 

 

I will compare the results using another slicer software soon.

CFFFP_Plaintriangle.3mf

CFFFP_Plaintriangle.gcode