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Overhangs look terrible, overextruded?  

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Alex
 Alex
(@alex-26)
Active Member
Overhangs look terrible, overextruded?

My self-built MK3 has had issues printing overhangs from the beginning, but now even the most minimal under 45º angles are an issue.

I'm trying to print this little boat, which is supposed to be printable without supports. I'm printing at 0.2mm with Prusa PLA. The first couple of layers come out just fine, but when it starts to print the bottom curve (which is got to be less than 30º) it's like the extruder is too slow and I think I hear it scraping on the model. I tried to record the noise I hear that I think is the extruder hitting the infill: .

Here you can (sort of) see that the first layers are ok, then it looks terrible, and then it looks perfect:

Here's another shot, but this time with the bottom layer sort of visible:

( https://imgur.com/a/MERRa )

Why do my overhangs look so terrible? Could there actually be something wrong with the height of the extruder, or is that noise something else? Why would it be overextruding in that part? Any ideas would be helpful, this is driving me crazy!

Posted : 12/04/2018 4:22 pm
motocoder
(@motocoder)
Trusted Member
Re: Overhangs look terrible, overextruded?

That noise sounds like the same noise I get, which I have determined is the X belt rubbing the side walls of the idler.

Posted : 12/04/2018 4:39 pm
Alex
 Alex
(@alex-26)
Active Member
Topic starter answered:
Re: Overhangs look terrible, overextruded?

I don't hear that noise all the time, though. For example, when it's printing the more up-right portion of the boat I don't hear it at all.

Posted : 12/04/2018 4:42 pm
RH_Dreambox
(@rh_dreambox)
Prominent Member
Re: Overhangs look terrible, overextruded?

The problem may be caused by the 45 degree rule?
An leaning surface below 45° can not be printed without support material.
Try changing the angle to 45° or more, or use "support material".

Bear MK3 with Bondtech extruder

Posted : 12/04/2018 5:49 pm
Nikolai
(@nikolai)
Noble Member
Re: Overhangs look terrible, overextruded?

Try to lower the temperature and slow down. Minimum three outer layers. Outer layers should be printer from inside to outside.
If that doesn't help, try a different (brand) filament. Some can handle overhangs better then the other.

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram

Posted : 12/04/2018 7:12 pm
Alex
 Alex
(@alex-26)
Active Member
Topic starter answered:
Re: Overhangs look terrible, overextruded?

Thanks a lot for the suggestions, I'll give them a shot and let you know how it comes out!

Posted : 13/04/2018 9:35 am
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