2

Everywhere you can read how to try to "hide" the seam, but nowhere there is an attempt to eliminate this problem. And the proof that it is possible is the prepared G-code added to the Ender printer on the SD card. (the exact name of the file is 3-Cat.gcode)

This little figurine has no seam at all! The print is so perfect that I can't believe it.

The question is why slicers don't create such G-codes so that the seam is hidden inside the printed object, not on its wall.

I have printed this figurine six times already, in different colors and different brands of filament. All prints are perfect!

What do you think about it? Can this be done in a slicer? (I can add this file somewhere but I don't know where.)

Seam in diferent retraction distance (retract on layer change turned on): seam in diferent retraction distance

Rigid
  • 21
  • 3
  • Can you include a link to the file so folks trying to answer can analyze it to see what it's doing? – R.. GitHub STOP HELPING ICE Apr 04 '23 at 02:05
  • Sure, added above. – Rigid Apr 04 '23 at 09:57
  • where can i upload the file so that the moderator won't delete it? -.-' – Rigid Apr 07 '23 at 11:40
  • We need information on the used slicing parameters, you should also share your own sliced G-code for the knobs above. Being a circular object with no corners you can never hide the seam, you can mitigate the effects but it will always be somewhat visible, even on well tuned Ultimaker printers. – 0scar Apr 07 '23 at 13:01

3 Answers3

1

This answer adresses the seam in the cat model. While it appears that there is no seam printed in this model, it most certainly is printed, but it is cleverly hidden in a sharp corner for you not to see the seam. Furthermore, by clever use of printing the infill first and then the outer perimeter, it appears that there is no seam. There isn't a definite start and stop (no retraction from infill to outer perimeter) and continues inner perimeter printing after the outer perimeter.

You can load the model in an online G-code visualizer to see for yourself. The Creality Cat is a specific showcase to show it's capabilities, but cannot simply be applied to all geometries, a sphere is difficult to print perfectly.

0scar
  • 35,554
  • 12
  • 65
  • 151
0

It's done by tweaking the retraction setting in your slicer.

In Cura the main setting affecting this is under 'Travel'.

In the 'Travel' settings is 'Enable retraction', and 'Retract at layer change'.

This will retract the filament and you won't get a seam.

Kilisi
  • 1,365
  • 4
  • 15
  • tested on a small cylinder, the seam is still visible. :( – Rigid Apr 04 '23 at 10:03
  • I would expect retraction to be on by default in any reasonable profile. However, the parameters might not be very good. – R.. GitHub STOP HELPING ICE Apr 04 '23 at 14:47
  • I turned on "retraction on layer change", printed the same test model 6 times (with retraction distance 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9) and I don't see any difference in the seam... either CURA is broken or I'm retarded... – Rigid Apr 07 '23 at 11:46
0

Getting a seam that's not ugly is a matter of having proper retraction and Z-travel settings that don't let the nozzle ooze when starting/stopping an extrusion. These differ for every printer, but the settings in the Creality-sliced file are 0.8 mm retraction length, and 40 mm/s retraction (and unretraction) speed. These are a very good baseline to start tuning from for a direct drive extruder. Otherwise I don't see anything remarkable about their slicing. You can open it up in a gcode analyzer like https://gcode.ws or https://gcodeanalyser.com to see where their seams are and check if anything else looks special to you.

Faster Z moves will also help and let you turn off "retract at layer change" if you like, which can help. They have not done this in their file; it's sliced with a painfully slow 5 mm/s Z travel speed. Cura doesn't let you access this directly but it reuses the Z-hop speed, even if Z-hop isn't enabled, as the Z travel speed for layer changes. Increasing it won't help much without also increasing the Z acceleration in the printer firmware, though, since the moves are so short they don't have significant time to accelerate. I use 80 mm/s with 750 mm/s² for Z on my Ender, but I'm not sure if that's achievable without TMC 2209s stepper drivers in Spreadcycle mode. In any case, you can get completely acceptable seams without fast Z travel as long as you have "retract at layer change" on.

R.. GitHub STOP HELPING ICE
  • 12,763
  • 5
  • 32
  • 76
  • Thank u for reply. I don't understand why we are writing here about changes in the hardware or software of the printer... as I wrote earlier, the model added to the printer on the SD card is printed seamlessly, there is no seam at all. I added a link to this .gcode file (but the moderator removed it. BTW how can I add it to make it acceptable to the moderator?) I currently have layer change retraction turned on and I tried to print a small model with a retraction distance of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9... and I don't see any differences in these models in the seam... – Rigid Apr 07 '23 at 11:56
  • @Rigid: The second paragraph is more general information about the way seams can bulge, and as I said in the final sentence, is not needed to match what Creality did. "In any case, you can get completely acceptable seams without fast Z travel as long as..." – R.. GitHub STOP HELPING ICE Apr 07 '23 at 13:51