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horizonatal external lines missed out?

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hello, me again.

so someone called me out on this in a previous thread, about missing out some lines, almost like it was going to separate. so i was printing the ultimaker handle as a nice big test print, and i had quite a few places where it almost missed out on extruding the outer wall.

6opg.jpg

4lb9.jpg

so it isn't effecting the internal strength, just looks a bit ugly.

currently using the latest version of cura and firmware on the "original" machine, and using ultimaker blue filament (not that you can tell from the lovely colour balance!)

egsz.png

doh8.png

and here are my machine specs im using.

 

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You're under-extruding in general - hence the mesh on top not closing up completely, despite printing with 8 layers. You're printing fairly thick layers, and moderately fast, so I'd be inclined to raise the temperature up to more like 230ºC, to make the plastic easier to squeeze out of the nozzle.

The side walls may just be a result of that, perhaps combined with the plastic not feeding off the roll as easily as it might, causing even more under extrusion. The other thing to try is turning off 'enable combing' as that can cause the head to ooze on long moves inside the part, leaving too little plastic when the perimeter resumes.

 

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i thought the layers may be slightly too thick, and it is going fast ish (its a relatively big part)

excellent about the enable combing. that has always bugged me, and looks very ugly.

i think im printing at such low temperatures as lower temperatures are slightly better for stringing, but the new cura with more retraction has helped that dramatically.

 

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I wouldn't expect much stringing on this object because it doesn't have separate islands (but you never know with cura!).

Actually the letters - those might have stringing.

Anyway you can help the underextrusion two different ways - either slow it down or heat it up. Your choice. And when I say slow it down I mean 40mm/sec. And when I say hotter I mean 230C or even 240C.

I'd be tempted to print 90% of it at 240C, 60mm/sec and then use tweakAtZ to switch to 30mm/sec at 205C for the letters on top.

 

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Notice how one set of the surface weirdness corresponds to the screw holes in the side of the part? That's what makes me think it's retraction/oozing related. Because it's a large part, the head probably does a lot of traveling inside the shape to get over and print that island between the two screw holes. I think that's depleting the head of plastic, so when you start printing again, you get under extrusion for a bit.

 

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Aren't there signs of severe backslash as well? Look at how the lines are connecting to the edges of the part in the middle of the first picture. They're coming in, make a sharp turn and then on the way back out makes another sharp turn and lays down plastic almost on top of the previous line. Or am I just seeing things?

 

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