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Trappify
(@trappify)
Member
Bad prints

Hi,

I'm a beginner at this and new on the forum. My printer is a MK3S+ and it's been running great for a year or so (not sure about hours). I print mostly in PETG. Now, lately my prints are getting worse. "blobs" are forming on the surface which sometimes leads to a crash. I think it all started after I printed in TPU, but not sure if it's related. Here's a picture from today, when printing with Prusa PETG and stock settings/presets (I think) in Prusa Slicer.

What could be the reason? What do I need to do to get back to nice prints again? New nozzle maybe?

Thanks,

Andreas

Best Answer by Eef:

I am no specialist (there are many better on this forum), but let me give it a try. 
Giving the size of the object (Printing an LP? 😉 ) your sheetbed is very flat. 
There is more filament extruded then needed/used, the PETG sticks very well to the nozzle, so it is towed and grows untill it falls of -> blob. 
Also I see that the nozzle is "ironing" the first layer. That is OK (as far as I know) for PLA, but not for PETG. PETG sticks much more to the nozzle then to the plate, that is why the Z-adjustment is mostly about 0,2 mm higher then for PLA. 
My idea: The Z-heigth is set too close to the plate, and should be set higher. 
I use this for adjusting: https://www.printables.com/model/251587-stress-free-first-layer-calibration-in-less-than-5/files  
Really best to use white filament for this. You see everything. 

PS: Could it be you printed PLA in between and did not set/reset the Z-heigth? 
Or nozzle change? What could also give a difference. 

Posted : 19/05/2024 3:23 pm
Eef
 Eef
(@eef)
Reputable Member
RE:

I am no specialist (there are many better on this forum), but let me give it a try. 
Giving the size of the object (Printing an LP? 😉 ) your sheetbed is very flat. 
There is more filament extruded then needed/used, the PETG sticks very well to the nozzle, so it is towed and grows untill it falls of -> blob. 
Also I see that the nozzle is "ironing" the first layer. That is OK (as far as I know) for PLA, but not for PETG. PETG sticks much more to the nozzle then to the plate, that is why the Z-adjustment is mostly about 0,2 mm higher then for PLA. 
My idea: The Z-heigth is set too close to the plate, and should be set higher. 
I use this for adjusting: https://www.printables.com/model/251587-stress-free-first-layer-calibration-in-less-than-5/files  
Really best to use white filament for this. You see everything. 

PS: Could it be you printed PLA in between and did not set/reset the Z-heigth? 
Or nozzle change? What could also give a difference. 

We will do what we have always done. We will find hope in the impossible.

Posted : 19/05/2024 9:00 pm
Trappify liked
Trappify
(@trappify)
Member
Topic starter answered:
RE: Bad prints

Thanks for your reply @Eef. I think you're right about the Z height. Have searched around the forum a bit and that seems to be the common answer. Learned something new there! I'm running the height Z using the model you linked as we speak. Yeah, it's an LP 😀 haha. No, it's a 320 teeth GT2 pulley. The absolute max size I could cram in there.

Posted : 20/05/2024 5:47 am
Eef
 Eef
(@eef)
Reputable Member
RE: Bad prints

 

Posted by: @trappify

The absolute max size I could cram in there.

May I advice to print it in an angle of 45 degrees. See this video:
No warping, no attachement issue, and you can go bigger!

We will do what we have always done. We will find hope in the impossible.

Posted : 20/05/2024 9:32 am
Trappify
(@trappify)
Member
Topic starter answered:
RE: Bad prints

Thank you!

I also think one of my issues is leaking from the hotend, as I'm getting random blobs of filament throughout the print  (with a different color than what I'm currently printing in). So probably need to do some hotend cleaning and rebuild.

Posted : 20/05/2024 10:02 am
Trappify
(@trappify)
Member
Topic starter answered:
RE: Bad prints

Just circling back on this issue. I've learned three things:

1) If your hotend is oozing and dripping filament. Fix it asap! Mine (original) was leaking between the heater block and the heat sink. Removed it from the printer and tried to clean it, but just too messy. So I went and ordered a E3D Revo as replacement. Now installed and my prints are perfect again 🙂

2) Printing at 45 degrees is awesome for some objects. However not necessarily for the pulley I was printing related to this post.

3) Adjust the Z slightly higher for PETG compared to PLA.

 

Thanks @eef for putting me on the right track here.

Posted : 29/05/2024 10:35 am
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