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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, 2020 at 7:07

3 Answers 3

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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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I see this is an old post but I type anyway if someone else stumbles up in here with the same problem.

First of all, I have a Qidi X-max printer and it printed exactly as in the picture. I am not 100 percent sure because pictures don't tell everything. I googled it very hard to find people that had the same issue. I only find this but it didn't help me so much.

I took apart my printing head on the machine, it is built with a direct extruder. I found some screws were not tightened and the block was a bit loose. I could screw it in 1 whole turn. After that, I cleaned the gear for the extruder so all the old filament was gone. There was not much filament but better do it properly. After that, I screwed all back and it was gone. I can't say for sure what was the exact cause. But if I have to guess I think it was because of not having properly tightened screws. This problem occurred every time when it was starting a new layer. It was not squeezing properly from the beginning and after maybe 3-4 mm everything squeezing as it should. New layers and seams were affected by this. Holes at the beginning of the layer and holes in seams. I also tried increasing the temp and flow. Flow helped a little but not much. So check all the screws. The ones I found were holding the print head. If that doesn't help do as I did and see if that fixes the problem.

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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, 2020 at 23:08

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