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Big blobs on print confused smiley

Posted by Yves.E 
Big blobs on print confused smiley
February 20, 2017 09:11AM
Hi fellow 3D enthusiasts :-),

I (as a newbie) have recently made my own 3D printer that I'm adjusting right now. I've come to a point where I only get blobs in my print. I have searched a lot on the internet and came to the conclusion that it has something to do with the retraction settings. After some experimenting with the retraction speed and distance, the problem was not solved. The blobs are reproducible and see again in the same places every time I start the print.

I use Cura 15.04.6 as Slicer and print by SD card. I hope someone in this forum could help me with the blobs. Below I have an example of the blobs and a picture of my printer. Besides that, I have added the Cura settings in the Attachments.

Grtz,
Yves








Attachments:
open | download - cura1.JPG (37 KB)
open | download - cura2.JPG (36.6 KB)
open | download - cura3.JPG (21.3 KB)
Re: Big blobs on print confused smiley
February 20, 2017 10:23AM
Your blobs look like start/stop points as best as I can tell from the picture. Try slice something in Cura 2.3.1 which I found to have much better toolpaths than the Cura 15 versions.
Re: Big blobs on print confused smiley
February 20, 2017 11:41PM
One part of the problem is the long Bowden tube. Try to reduce the length by moving/rotating the extruder to some better place.

Also retraction speed in combination with z_lift is critical. I'd try 80mm/s retraction speed and no z-lift ( that's hidden in the expert section of Cura )
Re: Big blobs on print confused smiley
February 21, 2017 01:35PM
Thx for the replies PDBeal & o_lampe, I will try it out with some test!
Re: Big blobs on print confused smiley
March 02, 2017 04:35AM
After some tests I was unable to solve the problem using the retraction speed and the Cura version. The blobs kept coming back to the same place. After a new search on google I came on the 3d print part of Reddit. Someone else had the exact same problem and had also tried the exact same. He found the solution by halving the jerk.

After reading this have I done the same and this has solved the problem for me. See below the result, left the old situation and right the new one:





The only problem I still have is the lack of good cooling. I have orderd an extra fan to cool down the extruded filament.
Re: Big blobs on print confused smiley
March 14, 2017 04:03AM
order a few fans..cheeper ones seems to have bad and better ones, eather way it will go eventualy.
Re: Big blobs on print confused smiley
March 14, 2017 12:57PM
What were your settings and what are they now?
Re: Big blobs on print confused smiley
March 17, 2017 03:55PM
@munchit
I made a new fan duct with a normal fan and a centrifugal fan. The result is a verry clean print.

@Floyd
You can see my old settings in the attachment from my first post. The new settings are below.
Attachments:
open | download - Cura_settings.ini (10.8 KB)
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