Blobs in Vase Mode

[MasterFX]

Hi,
I recently printed some bigger vases in vase mode. I printed them on the Anet A8 with Skynet (Marlin) Firmware (Accel: 400, X/Y Jerk: 20).
But I have blobs on the vase, where there should be none. The gcode doesn't show any retractions (of cause because of the vase mode). Printing speed is 40mm/s and 60% underspeed, so the hole vase is basically printed with 24mm/s.
As you might see on the Image the blobs seems to be on positions were a facette changes to an other. So it might be a Acceleration/Jerk problem.
You can here while it is printing some kind of hiccup or a very short pause to think.

Under the microscope you can definite see that on the blobs is more material:

Any ideas to get rid of them?

[MasterFX]

I Just printed the same Vase with Cura and S3D. Cura wins... by far.. almost no blobs.
Since I didn't find any retraction gcodes in the generated files... what could be the problem. Okay Cura printed 50% longer...

[wirlybird]

Can you tell if the blobs are symmetrical, meaning are they happening at regular intervals or are they just random?
What is the material? Is it PETG? Maybe it is a slight over extrusion where it is building a little residue on the nozzle and then leaving it behind? Long shot on that one!
Have you disabled retraction completely but unchecking it on the first or second tab?

Just taking some guesses here!

[MasterFX]

Can you tell if the blobs are symmetrical, meaning are they happening at regular intervals or are they just random

More like random, but if they are there, they are on parts where two facettes touches each other.
What is the material? Is it PETG? Maybe it is a slight over extrusion where it is building a little residue on the nozzle and then leaving it behind? [/quote]
In this case it is PLA but on PETG happens the same.

Have you disabled retraction completely but unchecking it on the first or second tab?

No not disabled. But in the whole Gcode is only 5 times retraction (G1 E-0.9000 F1800), but only on the solid layers and once at the end.

[wirlybird]

Odd stuff. What happens if you rotate the vase like maybe 45 degrees on the platform then print?

[MasterFX]

Since it is a twisted vase I don't think I get any change since every surface is affected on any angle.

[wirlybird]

Yea, I figured as much but the idea is to get it to slice it a bit different and see if it helps.

[Mogal]

Try slowing down the print.

It might be slowly building up around the nozzle, then when there is enough, it blobs up onto the print.

[MasterFX]

It might be slowly building up around the nozzle, then when there is enough, it blobs up onto the print.

As I already sad, you can defenite hear when a blob is printed, since the print is slowed down for fraction of a second. This is an active desired process, not a random thing. But in the G-Code is nothing which has anything todo with slowing down, retract or something else. Just pure G1 X... Y... Z... E... G0 E0.... And some times a sticky G1 ...... F1400 for speed

I just printed the Model again in S3D with the same printing time as in Cura.
Still much more blobs than with Cura. And even as it looks like in the image, the slower print with S3D has almost all blobs that the fast one has, they are only not as much visible, but if you turn it in the light you can still the most of them

Maybe some one else can try it: https://www.thingiverse.com/thing:606386/#files (a_new_vase4.stl)

Two friends of mine tried that already and all have the same blobs (all have S3D and Anet A8)

[wirlybird]

If I remember I will try.
Do you see any differences in the actual hardware setup between S3D and Cura? Just a thought.