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mikey

Is this just under-extrusion?

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It looks like underextrusion but I don't know why it would get worse at the top. You had retraction everywhere so if it had anything to do with retraction (such as retraction speed so high it missed steps on the extruder) then it should appear everywhere. Did you lower the temp further up? Did you crank the fan higher further up? Maybe the PLA on the spool got slightly more tangled and you were on the verge the whole time?

Anyway to fix this kind of thing you can either extrude less PLA per second or you can raise the temp. Lower the speed will get you better quality overall so if you are patient then that is the better choice. If you are impatient like me then crank the temp to 240C and let the plastic flow! Of course you will get much worse stringing at 240C. Everything is a tradeoff.

 

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Did you print all the parts at once, or one at a time? Where there other parts printing when the bad part was printing?

In addition to George's comments, you might check your minimum layer time: make sure the plastic has time to cool properly before more is laid down on top.

 

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Did you print all the parts at once, or one at a time? Where there other parts printing when the bad part was printing?

In addition to George's comments, you might check your minimum layer time: make sure the plastic has time to cool properly before more is laid down on top.

 

Min layer time was 6 seconds but all of the objects were printing at once. And I had left this print overnight so I didn't change any settings. All the parts look like this not just this one. I also seem to get bump outs on corners to maybe It was too fast of a print?

 

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60 mm/s isn't really that fast, so long as you weren't running really cold - my guess would be that possibly the filament got tangled up a little bit, so the extruder had a harder time feeding it cleanly.

Over on my http://www.extrudable.me/2013/04/18/exploring-extrusion-variability-and-limits/ about extrusion speeds and limits, ErikZalm has recently commented on some tests he's done using an encoder to measure filament feed rates - reinforcing my rather more indirect findings, and directly observing what I had long suspected - that the difficulty of getting filament off the spool materially affects the extruder feed rate.

Make sure you have plenty of filament unspooled and available to the feeder - especially if leaving the printer for a long print.

 

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