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Blobs with Prusament PETG  

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daniel.r3
(@daniel-r3)
Active Member
Blobs with Prusament PETG

Hi everyone,

just started using the Prusament PETG filament. I'm using the standard PrusaSlicer profile for the filament and getting pretty extensive blobs on the print surface:

My first idea was over-extrusion but in general the print looks good (top layers also).

I read that PETG tends to be more stringy than PLA. Since the blobs are located in similar spots I assume it could result from traveling moves and the strings produced by it.

Appreciate input from more experienced PETG users 🙂

Cheers,

Daniel

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Posted : 11/02/2021 10:21 am
Dan Rogers
(@dan-rogers)
Noble Member
RE: Blobs with Prusament PETG

So many possible causes here.   I'll share a couple of thoughts

Switching to PETG is going to introduce learning curves.  Welcome.

Blobbing, in my experience, is a first layer problem.  PETG nearly always requires a different first layer calibration Z height for a good adhesion on the first layer.  If the first layer is wonky, the head will build up blobs, and then these show up in later layers as the fall off the head - usually with poor results.

Your picture doesn't show the side that was on the bed (at least it doesn't seem to be the bed side).    Could you post a pic of the side that was on the bed?

Posted : 11/02/2021 6:56 pm
fuchsr
(@fuchsr)
Noble Member
RE: Blobs with Prusament PETG

I agree with @dan-rogers. Looks like a first layer calibration issue to me. I've printed extensively with Prusament PETG, all sorts of colors, and while I get occasional stringing, with proper live Z I found it to be extremely reliable. I would start my debugging of this issue by re-doing live Z for this filament.

 
Posted : 11/02/2021 8:42 pm
daniel.r3
(@daniel-r3)
Active Member
Topic starter answered:
RE: Blobs with Prusament PETG

Thanks for your replies!

I'm definitely more experienced with PLA... But the fact that PETG can be sanded well and is not going to swim away in the sun really wanted me to try it out more 🙂

So first some more pictures:

 

The funky edges are from the half removed brim (wanted to have a little more surface area). I tweaked the Z height already a bit since it was a little high before. Now its squishing it more into the textured bed but still no buildup during the first layer. The Blobs did also occur with the higher Z value.

As seen in this picture, the outside of the print is pretty perfect (apart from some layer inconsistencies)

I had a look at the travel moves in PrusaSlicer and as suspected there is a travel move on all the locations where the blobs are.

What do you think about the first layer? Apart from that: maybe I have a little over-extrusion? I heard that PETG is very unforgiving in that regard. So maybe there is a small buildup of extra material that is dragged off on the travel location?

I understand that I have to probably just test different things to figure it out. But I thought there might be some common problems causing this 🙂

And I was a little disappointed of the "default" result of a Prusa made filament paired with their slicer and their printer...

Thanks for your help! Really appreciate it 🙂

This post was modified 10 months ago 2 times by daniel.r3
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Posted : 11/02/2021 9:45 pm
Dan Rogers
(@dan-rogers)
Noble Member
RE: Blobs with Prusament PETG

looks like you nailed it.  

Don't be too disappointed - there are too many variables to go wrong for the 3d printer to be as reliable as a television or a can opener.  They could not know in advance which sheet you are using, what Z height you selected during calibration.  The filament profiles go a LONG LONG way to getting you close - and it's a freaking miracle that you only have to turn one knob to solve so many first layer problems.

Posted : 11/02/2021 10:07 pm
daniel.r3
(@daniel-r3)
Active Member
Topic starter answered:
RE: Blobs with Prusament PETG

I think that sounded more negative than I wanted. It's pretty cool that I could do a 20h print without much tweaking beforehand with good results.

Probably PLA just spoiled me with very good results out of the box 🙂

Thanks for the feedback!

This post was modified 10 months ago by daniel.r3
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Posted : 11/02/2021 10:16 pm
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