strange holes in the print!

[mariocoppola 1]

Hi all,

I am experimenting a bizarre issue: there are some strange, small "holes" on the external perimeter of my print, but in the gcode there is nothing there to justify them, neither a retraction.

Anyone could help with this??

here is the link to download the file: https://we.tl/t-3ZEKvScEtM

Thank you... 😞

[burtoogle 516]

I would hazard a guess and say you are using too much retraction which is sucking air into the extruder.

[mariocoppola 1]

i don't think so, because I am using always the same retraction that is 5mm... but I set the retraction speed at 30: maybe it is too low?

[mariocoppola 1]

or maybe it could be the z hop that is 1mm?

[burtoogle 516]

Yes, but your model has no infill and you normally print infill before walls (so it says in your profile) so the air could possibly be expelled in the infill (when you use infill) and you would not notice the holes.

[mariocoppola 1]

ok, so what you suggest? try to speed up the retraction?

[mariocoppola 1]

10 minutes ago, burtoogle said:

Yes, but your model has no infill and you normally print infill before walls (so it says in your profile) so the air could possibly be expelled in the infill (when you use infill) and you would not notice the holes.

 

of course my model is 2 perimeters! so it is strange, I should see the hole in the internal perimeter and close to the starting point, instead the holes are in the external perimeter and far from the starting!

[burtoogle 516]

3 minutes ago, mariocoppola said:

of course my model is 2 perimeters! so it is strange, I should see the hole in the internal perimeter and close to the starting point, instead the holes are in the external perimeter and far from the starting!

 

You can normally tell if it's air because you can actually hear little pops as the bubbles come out of the extruder.

 

[mariocoppola 1]

32 minutes ago, mariocoppola said:

ok, so what you suggest? try to speed up the retraction?

 

[burtoogle 516]

I would suggest try reducing the retraction distance in 0.5mm steps and see if (a) the holes go away because you had too much retraction or (b) you start to get stringing or blobs because you have not enough retraction. Obviously, you can test this on a small model rather than your big print.