Circles are not closed correctly

[3DinoPrint]

Printer: Voron 2.4, 300x300
Duet 2 Wi-Fi, 3.4.5
Prusaslicer 2.5.2

In the following picture the circles are not closed exactly. The line goes inwards, about 1mm. This closing-point differs in position from circle to circle. The outer line is closed correctly, so it might not be a mechanical issue of the printer.

The next picture shows the first circle left down together with the closing point of the outer line.

[dc42]

@3DinoPrint please provide the GCode file that you used to print this.

[3DinoPrint]

@dc42 Thank you for your quick response. Here please find the gcode for the skirt and the first circle at the left bottom:

; generated by PrusaSlicer 2.5.2+win64 on 2023-04-21 at 13:10:05 UTC

M107
;Startsequenz

G32 ;homing and levelling ;z bei 8mm

G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S205 ; set extruder temp
M140 S60 ; set bed temp

M190 S60 ; wait for bed temp
M109 S205 ; wait for extruder temp

G1 X20 Y20 F6000 ; go outside print area
G92 E0
G1 Z0.2 F720

G1 X100 E12.5 F1000 ; intro line
G92 E0
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion

;LAYER_CHANGE
;Z:0.3
;HEIGHT:0.3
;BEFORE_LAYER_CHANGE
;0.3
G92 E0

G1 Z.3 F18000
;AFTER_LAYER_CHANGE
;0.3
G1 E-.75 F3000
G1 Z.7 F18000
G1 X49.682 Y56.608
G1 Z.3
G1 E.75 F1800
M204 P1000
;TYPE:Skirt/Brim
;WIDTH:0.84
G1 X51.315 Y55.175 E.2102
G1 X54.103 Y53.182 E.23151
G1 X57.075 Y51.477 E.23151
G1 X60.203 Y50.076 E.23151
G1 X63.454 Y48.993 E.23151
G1 X66.797 Y48.24 E.23151
G1 X70.011 Y47.837 E.21333
G1 X71.824 Y47.743 E.17562
G1 X147.572 Y46 E7.32983
G1 X219.776 Y45.268 E6.98533
G1 X223.006 Y45.51 E.21332
G1 X226.382 Y46.096 E.23151
G1 X228.226 Y46.565 E.18402
G1 X231.471 Y47.665 E.23151
G1 X234.591 Y49.083 E.23151
G1 X237.396 Y50.703 E.21332
G1 X240.184 Y52.696 E.23151
G1 X241.641 Y53.918 E.18402
G1 X244.087 Y56.318 E.23151
G1 X246.169 Y58.799 E.21332
G1 X248.107 Y61.625 E.23151
G1 X249.059 Y63.272 E.18401
G1 X250.464 Y66.19 E.21332
G1 X251.645 Y69.407 E.23151
G1 X252.16 Y71.238 E.18402
G1 X252.83 Y74.599 E.23151
G1 X253.162 Y78.01 E.23151
G1 X254.778 Y149.178 E6.88656
G1 X252.762 Y215.772 E6.44523
G1 X252.431 Y219.162 E.2295
G1 X252.101 Y221.035 E.18402
G1 X251.246 Y224.354 E.23151
G1 X250.138 Y227.397 E.21332
G1 X249.356 Y229.131 E.18401
G1 X247.807 Y231.976 E.21332
G1 X245.884 Y234.812 E.23151
G1 X244.698 Y236.3 E.18402
G1 X242.361 Y238.805 E.23151
G1 X239.785 Y241.066 E.23151
G1 X237.786 Y242.527 E.23955
G1 X235.695 Y243.854 E.23955
G1 X232.65 Y245.426 E.23151
G1 X229.463 Y246.686 E.23151
G1 X226.167 Y247.624 E.23151
G1 X222.794 Y248.228 E.23151
G1 X219.253 Y248.498 E.24352
G1 X71.324 Y250.973 E14.31265
G1 X68.094 Y250.731 E.21332
G1 X64.717 Y250.145 E.23151
G1 X62.874 Y249.675 E.18402
G1 X59.629 Y248.575 E.23151
G1 X56.677 Y247.243 E.21332
G1 X53.704 Y245.538 E.23151
G1 X52.132 Y244.466 E.18402
G1 X49.6 Y242.447 E.21332
G1 X47.141 Y240.061 E.23151
G1 X44.931 Y237.442 E.23151
G1 X42.894 Y234.455 E.2497
G1 X41.264 Y231.441 E.23151
G1 X39.941 Y228.279 E.23151
G1 X39.4 Y226.653 E.16581
G1 X38.601 Y223.515 E.21332
G1 X38.08 Y220.127 E.23152
G1 X37.9 Y216.705 E.23151
G1 X38.346 Y80.301 E13.19576
G1 X38.697 Y76.892 E.23151
G1 X39.339 Y73.718 E.21332
G1 X39.854 Y71.886 E.18402
G1 X40.962 Y68.843 E.21332
G1 X41.744 Y67.109 E.18401
G1 X43.293 Y64.265 E.21332
G1 X45.216 Y61.428 E.23151
G1 X46.402 Y59.941 E.18402
G1 X48.739 Y57.435 E.23151
G1 X49.614 Y56.667 E.11261
M204 P3000
G1 E-.75 F3000
G1 X52.619 Y59.395 F18000
G1 E.75 F1800
M204 P1000
;TYPE:External perimeter
;WIDTH:0.599897
G1 X53.777 Y58.423 E.2
G1 X54.981 Y57.511 E.2
G1 X56.229 Y56.659 E.2
G1 X57.518 Y55.871 E.2
G1 X58.844 Y55.148 E.2
G1 X60.205 Y54.493 E.2
G1 X61.597 Y53.906 E.2
G1 X63.017 Y53.389 E.2
G1 X64.461 Y52.943 E.2
G1 X65.925 Y52.57 E.2
G1 X67.405 Y52.27 E.2
G1 X68.899 Y52.045 E.2
G1 X70.402 Y51.894 E.2
G1 X71.911 Y51.818 E.2
G1 X73.422 Y51.818 E.2
G1 X74.931 Y51.893 E.2
G1 X76.434 Y52.043 E.2
G1 X77.928 Y52.268 E.2
G1 X79.409 Y52.567 E.2
G1 X80.873 Y52.939 E.2
G1 X82.317 Y53.384 E.2
G1 X83.737 Y53.901 E.2
G1 X85.129 Y54.487 E.2
G1 X86.491 Y55.142 E.2
G1 X87.818 Y55.865 E.2
G1 X89.107 Y56.652 E.2
G1 X90.355 Y57.503 E.2
G1 X91.56 Y58.415 E.2
G1 X92.717 Y59.386 E.2
G1 X93.825 Y60.413 E.2
G1 X94.889 Y61.504 E.1018
G1 X95.889 Y62.637 E.2
G1 X96.83 Y63.819 E.2
G1 X97.712 Y65.045 E.2
G1 X98.531 Y66.315 E.2
G1 X99.287 Y67.623 E.2
G1 X99.976 Y68.968 E.2
G1 X100.597 Y70.345 E.2
G1 X101.148 Y71.752 E.2
G1 X101.629 Y73.184 E.2
G1 X102.038 Y74.638 E.2
G1 X102.374 Y76.111 E.2
G1 X102.636 Y77.599 E.2
G1 X102.823 Y79.098 E.2
G1 X102.936 Y80.605 E.2
G1 X102.973 Y82.108 E.10046
G1 X102.935 Y83.625 E.10136
G1 X102.822 Y85.132 E.2
G1 X102.634 Y86.631 E.2
G1 X102.371 Y88.119 E.2
G1 X102.035 Y89.592 E.2
G1 X101.629 Y91.033 E.10002
G1 X101.148 Y92.465 E.2
G1 X100.597 Y93.872 E.2
G1 X99.976 Y95.249 E.2
G1 X99.287 Y96.594 E.2
G1 X98.531 Y97.902 E.2
G1 X97.712 Y99.171 E.2
G1 X96.83 Y100.398 E.2
G1 X95.889 Y101.58 E.2
G1 X94.889 Y102.713 E.2
G1 X93.835 Y103.794 E.2
G1 X92.727 Y104.822 E.2
G1 X91.57 Y105.794 E.2
G1 X90.366 Y106.706 E.2
G1 X89.118 Y107.557 E.2
G1 X87.829 Y108.346 E.2
G1 X86.502 Y109.068 E.2
G1 X85.141 Y109.724 E.2
G1 X83.749 Y110.311 E.2
G1 X82.33 Y110.828 E.2
G1 X80.886 Y111.274 E.2
G1 X79.422 Y111.647 E.2
G1 X77.942 Y111.947 E.2
G1 X76.448 Y112.172 E.2
G1 X74.944 Y112.323 E.2
G1 X73.435 Y112.399 E.2
G1 X71.925 Y112.399 E.2
G1 X70.416 Y112.324 E.2
G1 X68.912 Y112.174 E.2
G1 X67.418 Y111.949 E.2
G1 X65.938 Y111.65 E.2
G1 X64.473 Y111.278 E.2
G1 X63.03 Y110.833 E.2
G1 X61.61 Y110.316 E.2
G1 X60.218 Y109.73 E.2
G1 X58.856 Y109.074 E.2
G1 X57.529 Y108.352 E.2
G1 X56.24 Y107.565 E.2
G1 X54.992 Y106.714 E.2
G1 X53.787 Y105.802 E.2
G1 X52.629 Y104.831 E.2
G1 X51.522 Y103.804 E.2
G1 X50.458 Y102.713 E.1018
G1 X49.458 Y101.58 E.2
G1 X48.516 Y100.398 E.2
G1 X47.635 Y99.171 E.2
G1 X46.815 Y97.902 E.2
G1 X46.06 Y96.594 E.2
G1 X45.371 Y95.249 E.2
G1 X44.75 Y93.872 E.2
G1 X44.199 Y92.465 E.2
G1 X43.718 Y91.033 E.2
G1 X43.309 Y89.579 E.2
G1 X42.973 Y88.106 E.2
G1 X42.711 Y86.618 E.2
G1 X42.523 Y85.119 E.2
G1 X42.412 Y83.625 E.10002
G1 X42.374 Y82.115 E.2
G1 X42.411 Y80.605 E.2
G1 X42.523 Y79.098 E.2
G1 X42.711 Y77.599 E.2
G1 X42.973 Y76.111 E.2
G1 X43.309 Y74.638 E.2
G1 X43.718 Y73.184 E.2
G1 X44.199 Y71.752 E.2
G1 X44.75 Y70.345 E.2
G1 X45.371 Y68.968 E.2
G1 X46.06 Y67.623 E.2
G1 X46.815 Y66.315 E.2
G1 X47.635 Y65.045 E.2
G1 X48.516 Y63.819 E.2
G1 X49.458 Y62.637 E.2
G1 X50.458 Y61.504 E.2
G1 X51.512 Y60.422 E.2
G1 X52.553 Y59.456 E.0949
M204 P3000
G1 X53.188 Y59.586 F18000
G1 E-.75 F3000
G1 X66.038 Y122.577 F18000
G1 E.75 F1800
M204 P1000
G1 X67.516 Y122.201 E.1018
G1 X68.996 Y121.902 E.2
G1 X70.49 Y121.677 E.2
G1 X71.994 Y121.527 E.2
G1 X73.503 Y121.452 E.

[droftarts]

@3DinoPrint It looks more like a backlash issue to me. Check your pulleys are tight on the X and Y motor shafts, that the belt is correctly tensioned, and can move freely. There are lots of places it can snag on a CoreXY.

Ian

[droftarts]

@3DinoPrint Your gcode only shows the perimeter and the first circle in the bottom left. Upload the whole file. Though from that snippet the circle looks round in a gcode viewer, whereas your picture looks like the two opposite sides (SE and NW) are flattened, which is classic backlash.

Ian

[3DinoPrint]

@droftarts It was the tension of the belts. I increased it, more on the left than on the right side and the circle is a circle
Thank you for your observation.