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Bad overhang surface

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Posted · Bad overhang surface



I have been printing some easter eggs the last couple of days but I keep running into the same problems.

First of all the overhang surface just looks really bad.(look at first picture)

and second I keepo getting lines from where the printhead starts an layer (second picture)

How can I solve these problems?



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Posted · Bad overhang surface

I don't see any photos.  Just start a post and drag an image that's on your computer hard drive somewhere onto the post.  Or if you have the pictures posted on some internet service and have the url you can click "insert other media".

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Posted · Bad overhang surface

ABS!  Difficult material - are you sure you don't want to print PLA?  It's a newer, better material for most applications.  Or if you need high temp materials there are other options like nGen/PET/CPE.


Is this a UM3?  3% is about right for ABS on Um3.  Or 30% for ABS on a UM2.


Basically, if you can print any cooler it will look a bit better (but the part will be weaker but you probably don't mind as if you wanted strong prints you'd probably not be printing ABS - see what I did there?  Another dig against ABS).


I would try printing 10C cooler (which may start to underextrude and/or layers to split so you might have to enclose the printer in those cases).  Make sure walls are at least 2 shells thick and make sure it's printing the inner shell first (it does this by default but I often swap that around) so the inner shell helps hold the outer shell in place.


The basic problem is that the filament is like honey as it comes out of the nozzle and shrinks very quickly and it sticks to itself like snot or mucus.  It's like a liquid rubber band. And on those outer points it pulls inwards a bit which raises up the outer edges (and you can hear the head smashing into those sometimes) and they look like this in the picture.  Sometimes it prints past the edge.  Now with PLA you should be able to do that much overhang and it should look much better (and I would say "fan is your friend" and to crank that fan).  But with ABS if you add too much fan the layers won't stick and it will start to split along layer lines before the print finishes.

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