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I'm new to 3D printing and I noticed some problems with my print.

I've printed it 3 times and releveled the bed. Now, I found that the right lower corner always has holes,

Printed model on bed shows incomplete coverage during initial layers

and some stringing problems

Printed model on bed shows stringing

Lastly, the place where there should be a full line suddenly becomes string-like, and it always happens at the same place.

Printed model has individual lines are thin and string-like

Another printed model has individual lines are thin and string-like

It's like my extruder pulls out the filament or fails to create filament in the area that should be filled with filament. Is it normal or did I set my printer wrong? I'm afraid it might cause holes in my new print.

There's also some stringing problem that causes the layer to be uneven.

Slicer: Cura 4.6

Settings:

Cura Speed settings

Cura Travel settings

Cura Material settings

Cura Cooling settings

My printer is Anycubic 4Max Pro

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  • $\begingroup$ Please share what slicer you're using and relevant settings, especially speed, retraction, and temperature. Since you mention stringing, that's likely the root cause of the underextrusion in the corner there - any stringing is material lost in one place that then doesn't get deposited in the place it was supposed to go, and it's usually caused by wrong retraction settings (wrong = off or too low, in most cases). $\endgroup$ May 16 '20 at 7:07
  • $\begingroup$ Hi, welcome to 3DPrinting.SE! Note that you problem is very similar to "What causes ripples on part of first layer?" with an answer describing what may have caused this. Note that the corner without filament is also caused by this issue. To cut it short, your nozzle is probably too close to the bed. $\endgroup$
    – 0scar
    May 16 '20 at 8:42
  • $\begingroup$ Possible duplicate of "What causes ripples on part of first layer?"? $\endgroup$
    – 0scar
    May 16 '20 at 8:43
  • $\begingroup$ @0scar I've updated my question, it always string in the same place like the picture, are those also affected by nozzle height? $\endgroup$ May 17 '20 at 3:00
  • $\begingroup$ Looks like the retraction settings are not optimal also. $\endgroup$
    – 0scar
    May 17 '20 at 6:39
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Anycubic 4Max Pro appears to be a direct drive printer (extruder motor is right on top of hotend). The 6.5 mm retraction on in your slicer settings is more typical of a Bowden setup, where the extruder motor lives off of the moving carriage, and has to move extra to compensate for slack in the tube to the hotend. Direct drive retraction distance is typically 1 mm to 3 mm. I bet you can retract faster than 25 mm/s- the speed matters. Also, 60 mm/s travel speed is quite slow. 150 mm/s is typical. Faster travel means less time to ooze.

Your initial layer print speed of 20mm/s is good, slow slow makes the first layer stick better. I don’t see your 1st layer thickness setting, but I have had good success with using a thick first layer with a chunky, wide line width (like 150% of nozzle size), even if the following layers are fine. The idea being that more plastic and height in the initial layer makes it less temperamental as far as bed leveling goes, and it holds together nicely.

The cobweb-like lines are from the Combing Mode setting in Cura, that ignores the retraction when traveling through infill. Unfortunately there is a setting that also ignores retraction on the bottom layer, you want to change that under “combing mode” it is set to “not in skin”, or combing is set to off.

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From the wispy horizontal lines within the perimeters in your second image, it appears that the nozzle is still oozing material during the travel moves. This is likely causing the hole in the corner and the wispy perimeters too. When the extruder reinserts the filament into the hotend after a travel move, it expects the same amount of material to be in the nozzle as when it extracted the filament, but some material has oozed out during the travel move so that is not the case. I had a similar issue with my printer, and was able to mitigate the problem by increasing the retraction extra prime amount in the material section of Cura. This should compensate for the material loss during the travel move by reinserting the filament slightly farther when starting the extrusion. This solution is not perfect as different lengths of travel allow different volumes of filament to ooze from the nozzle. If you want perfect prints, you may have to tune this to the model you are printing: larger models usually require larger travel moves which would allow more time for plastic to ooze from the nozzle.

If you try this, make sure to look for blobs at the start of extrude moves. If the prime amount is set to high, it can create blobs on the side of the model (or inside depending on which perimeter is extruded first) which could cause tolerance issues on more complex parts.

Personally, I have also added a small coast distance to the end of each extrusion (located in Cura's experimental section). This allows the nozzle to ooze into the perimeter of the part which should decrease the stringing on travel moves, and thus loss of material on travel moves.

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    $\begingroup$ This is all hacks to try to work around a problem that's entirely eliminated by correct use of retraction. $\endgroup$ May 24 '20 at 23:08

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