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small blobs on print

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i am wondering why my nozzle does an irregular "backstep"( on UMO and also UM2) with this PLA print?

settings :


walls:0.5 mm (more opacity)


temp: 200

spiralized: on



any suggestions would be very appreciated.

cheers imke


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Hi Imke,

Thank you for your email.

I don't see any odd behaviour in the video, do you have some examples to show your issue a little bit better?

What do you mean by backsteps?

You should keep your walls in a multitude of your nozzle, so make it: 0.4 or 0.8 or 1.2 instead of 0.5

Looking forward hearing from you!

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well it's not easy to see in the video- its in sec.11-12.

the the nozzle is moving a step back and you can also hear it, this happens not regular, what is also shown in the photo.

i turned spiralized on, because i didn't wanted a z scar , and thats why my wall thickness is not 0.8 (with 0.4 wall thickness the wall is too translucent) i am trying to find another video, but its difficult to capture...

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There's a TON of discussion about this on the forums somewhere. It's a relatively recent bug but it appeared before the latest rewrite of Cura. I'm not sure how far back you have to go to get before this bug but I think about a year. Try Cura 14.6.* or older (14=2014, 6 would be for example june). Cura has been working quite well for quite a while so these older versions are quite mature and safe and stable.

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I lost track of it. The developers of the new cura Engine I believe were discussing it so I think they are aware and it might be fixed in the latest version (15.6 or newer) I really don't know - but I certainly saw lots of discussion about this - I think it was in the spring.

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