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Every time I print a large area I get the pattern in the middle.

pattern on first layer

Below picture was taken during printing. The material isn't evenly laid flat on the bed and some are being scraped up.

It appears from some centimeters away from the edge and extends perpendicular to the nozzle moving direction.

during print

The pattern appears at the similar position when I print the same model again.

It's a delta printer. Print PETG on glass bed at 75 °C.

Update:

After adjusting delta height to add clearance, the first layer is super clean without any wave.

aleung
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    This has been asked before, this is the start of the effect, with even closer nozzle to gap (paper distance) you might run into having [waves in the first layer](https://3dprinting.stackexchange.com/questions/7229/what-causes-ripples-on-part-of-first-layer). This is caused by too much flow in too less space, increase the nozzle to bed distance for Z=0. – 0scar Feb 22 '22 at 18:27
  • Have you tried lowering the print-head travel speed? Do the "blobs" get shorter? – Criggie Feb 22 '22 at 19:04

1 Answers1

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The wavy lay down on the first layer usually indicates one of two problems:

  • The first layer is badly calibrated (too much distance, laying down in waves or too little, squeezing out in waves).
  • The plastic doesn't stick to the bed well enough.
Trish
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  • Thanks. Adding clearance solved the first layer issue. But there is still top layer quality issue on top layer. Please read my update. – aleung Feb 24 '22 at 02:16
  • Top layer is a different question from bottom – Trish Feb 24 '22 at 10:09
  • Yes I searched and found the top layer issue may be caused by Marlin firmware configuration. Removed from my question. – aleung Feb 25 '22 at 06:52