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szernex

Terrible curved perimeters with Cura

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Hi, I'm new to this forum so please forgive me if this has been covered somewhere else, a quick search didn't turn up any useful results.

 

So first up, let me show you this picture:

https://imgur.com/K70ctIR

 

Those two are the same model, printed on the same printer (CR-10S) back to back. The left one is sliced with Cura 3.5.1, right one with slic3r 1.3.1 dev 2018.10.23.1865.b582df12.32bit. Can someone explain to me why the Cura one looks so much worse when doing rounded perimeters like this?

What I've already tried:

  • using a default Cura profile for my printer
  • disabling and changing accel and jerk settings within Cura
  • slowing the print speed down all the way to 20mm/s
  • printing between 195 and 215°C (it's PLA)
  • using the "old" and new experimental jerk and accel settings in Marlin
  • Cura 3.4.1
  • (several other things I can't think of right now)

None of these things changed anything with the result.

 

Any input would be appreciated.

Edited by szernex

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Hi @szernex, comparing the two gcodes, the most obvious difference is that with Cura you are using relative extrusion mode and with Slic3r you are using absolute extrusion mode. Secondly, the Cura gcode appears to be using a mixture of line segment lengths around the curve and some of those segments are very short. The combination of short segments and relative extrusion can produce poor quality if the resolution of the extruder (steps/mm) is low. So I suggest you try turning off the relative extrusion option in Cura and also you could try increasing the Maximum Resolution experimental option to increase the line segment size. Hope this helps.

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40 minutes ago, smartavionics said:

Hi @szernex, comparing the two gcodes, the most obvious difference is that with Cura you are using relative extrusion mode and with Slic3r you are using absolute extrusion mode. Secondly, the Cura gcode appears to be using a mixture of line segment lengths around the curve and some of those segments are very short. The combination of short segments and relative extrusion can produce poor quality if the resolution of the extruder (steps/mm) is low. So I suggest you try turning off the relative extrusion option in Cura and also you could try increasing the Maximum Resolution experimental option to increase the line segment size. Hope this helps.

 

I turned on Relative Extrusion just today to test something else, I was doing the same print before with Absolute extrusion and it was exactly the same result. Maximum Resolution is currently at 0.01mm, what would be a reasonable value to test?

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26 minutes ago, szernex said:

I turned on Relative Extrusion just today to test something else, I was doing the same print before with Absolute extrusion and it was exactly the same result. Maximum Resolution is currently at 0.01mm, what would be a reasonable value to test?

 

Ah, OK. Well try using a much larger value, say 0.1mm and just see if it makes a difference.

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