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Extrusion blobs with S3D

Posted: Wed Mar 14, 2018 9:48 am
by deZeus
Hi,
I have a problem with the Slicer settings in S3D and I think I've already changed almost every parameter, but nothing worked.

When I'm printing, for example, the 20x20x20 calibration cube, I get blobs on the surface of the cube. These blobs are caused by the retraction of the extruder. I have changed the retraction distance, speed, acceleration and even the coast distance but the blobs are still there.

Now, I have sliced the calibration cube with Cura (v. 3.2). No special settings, almost the standard settings (even with retractions for every layer). And after the print was done, I had a nearly "perfect" cube with no blobs in my hand. So, it seems that it isn't a hardware problem, but which parameters are different? Has anybody a clue?

My setup:

Printer: Creality CR10
HotEnd: (original) E3D v6 Hotend
Filament: PLA

My settings:

Retraction Distance: 2.6mm - 3.0mm
Retraction Speed: 70 mm/s
Retraction Acceleration: 3000 mm/s²
XY printing speed: 60 mm/s
XY acceleration: 3000 mm/s²

I would be very happy to receive an answer! :-)

deZeus

Re: Extrusion blobs with S3D

Posted: Thu Mar 15, 2018 3:49 am
by rrdavis
If it was me, I'd probably use an even simpler test part. Try a standard cube without any lettering. Then align all of the start points to a specific edge in both programs and work on perfecting your retraction settings. The issue you are seeing is due to retractions, so if you get those tuned properly, it will go away.

Re: Extrusion blobs with S3D

Posted: Thu Mar 15, 2018 6:38 am
by deZeus
Hi rrdavis,

I get extrusion blobs on any of my models. And they are not random, they are always there where the retraction ends and the extraction goes further.

Beleave me, my retraction settings are still perfect (e.g. no stringing) and the parameters in both programs are the same. The "Cura Cube" has a perfect surface, the "S3D Cube" has blobs regardless of whether the starting points are on an edge or randomly distributed...

Best regards

deZeus

Re: Extrusion blobs with S3D

Posted: Thu Mar 15, 2018 7:58 am
by wirlybird
This is a very common issue in S3D. I have found that like rr said if you align the start points it should move those blobs to one side plus work with retraction and a negative restart can help reduce it. The negative restart though comes at a price! It can affect smaller detail areas of a print.

I have found though that for most real or non test prints it isn't to big of an issue.

However, working to reduce it on the cube is good practice.

Re: Extrusion blobs with S3D

Posted: Thu Mar 15, 2018 10:24 am
by deZeus
Hey wirlybird,

thank you for your response. Hm okay...I know what you mean with the negative restart, but isn't there any other solution? This would be more like a "dirty fixing", because if I would like to print a grid-model (e.g. klein bottle), then I'll have the problem that the printer extrude after 10-20 layers too less filament. And why doesn't cura need a negative starting point and print the cube without any blobs? Hm...I thought that a comparison of the code files (before , during and after the retraction) will show me the differences between the two slicers. But I'm not a expert in reading gcode :D . Below I have an snippet of the code (yeah I know. the position of the retraction aren't at the same position - but it is a retraction).

Code: Select all

--------------- CURA ---------------

G1 X30.859 Y21.894 E698.88516
G1 X30.859 Y22.094 E698.88947
M204 S3000
M205 X30 Y30
G0 F7200 X31.059 Y22.094
G0 X31.059 Y22.894
G0 X25.757 Y22.522
G0 X20.759 Y20.759
;TIME_ELAPSED:668.650992
;LAYER:31
G1 F2400 E695.88947
G0 F7200 X20.759 Y20.759 Z7.5
M204 S500
M205 X20 Y20
;TYPE:FILL
G1 F2400 E698.88947
G1 F2752 X39.239 Y39.239 E699.75871




--------------- S3D ---------------

G1 X44.040 Y27.069 E3.6713
G1 X42.931 Y25.960 E3.7220
G92 E0
G1 E-2.6000 F4200
; layer 33, Z = 7.507
; inner perimeter
G1 X44.400 Y25.600 F10800
G1 Z7.507 F1002
G1 E0.0000 F4200
G92 E0
G1 X44.400 Y33.210 E0.2455 F2363
G1 X42.458 Y33.209 E0.3082

Can you do something with it?

Best regards

deZeus

Re: Extrusion blobs with S3D

Posted: Fri Mar 16, 2018 3:55 am
by rrdavis
Like you said, those aren't in the same location, so it isn't easy to compare in the gcode or in real life (since the location will obviously impact what it looks like in a print).

Can you try printing a simple cube with both programs? Then you know the retraction should always take place at one of the corners, so it should be much easier to compare. If you can post sample gcode and maybe photos from those 2 tests, it will be easier to help.

Re: Extrusion blobs with S3D

Posted: Fri Mar 16, 2018 10:14 am
by deZeus
Hi rrdavis,

thank you for your help. I have attached a photo and the gcode files of the two cubes and below, there ist a snippet of the retraction gcode. The picture shows the retraction blobs on the right side.

Code: Select all

--------------- CURA ---------------

G1 X44.8 Y25.2 E183.39411
G1 X44.8 Y44.8 E184.01993
M204 S3000
M205 X30 Y30
G0 F7200 X44.6 Y44.8
G0 X44 Y44.118
G0 X25.759 Y25.759
;TIME_ELAPSED:203.098714
;LAYER:10
G1 F3600 E181.01993
G0 F7200 X25.759 Y25.759 Z2.2
M204 S500
M205 X20 Y20
;TYPE:FILL
G1 F3600 E184.01993
G1 F2657.4 X44.239 Y44.239 E184.8544
G1 X44.309 Y44.309




--------------- S3D ---------------

G1 X44.040 Y27.069 E3.7216
G1 X42.931 Y25.960 E3.7722
G92 E0
G1 E-2.6000 F4200
; layer 11, Z = 2.240
; inner perimeter
G1 X25.600 Y25.600 F10800
G1 Z2.240 F1002
G1 E0.0000 F4200
G92 E0
G1 X44.400 Y25.600 E0.6065 F2209
G1 X44.400 Y44.400 E1.2131
Best regards

deZeus

Re: Extrusion blobs with S3D

Posted: Sat Mar 17, 2018 4:47 am
by rrdavis
Well it looks like one of those is printing the infill before the perimeters, which means if never does a retraction on the perimeters at all. So it isn't really even comparing retraction settings, since one is never retracting there.

You could try going into the Advanced tab in S3D and disabling the "force retraction between layers" option. Then S3D won't be doing extra retractions either.

Might also be interesting to see if printing 3 outlines instead of 2 improves things at all

Re: Extrusion blobs with S3D

Posted: Sun Mar 18, 2018 1:37 pm
by Aha
Also, it's worth checking out the coast settings. That might fix the problem; a mix of coast and retraction.

I've noticed that s3d has both useful and useless extra things that you can/need to tweak. Sometimes they work better out of the box in other programs, sometimes in s3d. Seems to be the printer and who configures the initial settings for it.

Re: Extrusion blobs with S3D

Posted: Mon Mar 19, 2018 6:52 am
by wirlybird
deZeus wrote:
Fri Mar 16, 2018 10:14 am
Hi rrdavis,

thank you for your help. I have attached a photo and the gcode files of the two cubes and below, there ist a snippet of the retraction gcode. The picture shows the retraction blobs on the right side.

Code: Select all

--------------- CURA ---------------

G1 X44.8 Y25.2 E183.39411
G1 X44.8 Y44.8 E184.01993
M204 S3000
M205 X30 Y30
G0 F7200 X44.6 Y44.8
G0 X44 Y44.118
G0 X25.759 Y25.759
;TIME_ELAPSED:203.098714
;LAYER:10
G1 F3600 E181.01993
G0 F7200 X25.759 Y25.759 Z2.2
M204 S500
M205 X20 Y20
;TYPE:FILL
G1 F3600 E184.01993
G1 F2657.4 X44.239 Y44.239 E184.8544
G1 X44.309 Y44.309




--------------- S3D ---------------

G1 X44.040 Y27.069 E3.7216
G1 X42.931 Y25.960 E3.7722
G92 E0
G1 E-2.6000 F4200
; layer 11, Z = 2.240
; inner perimeter
G1 X25.600 Y25.600 F10800
G1 Z2.240 F1002
G1 E0.0000 F4200
G92 E0
G1 X44.400 Y25.600 E0.6065 F2209
G1 X44.400 Y44.400 E1.2131
Best regards

deZeus
Yup! I can reproduce the same results using S3D against Sli3r, QIDI Print or Flashprint. Same STL file run and get the exact same results on three different printers. S3D always does this.

I will bet that each time S3D leaves a blob on the corner it has just traveled from the opposite corner. I have fought it since Ver3 came out, first version I had!