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Is the MK4 to fast or to hot for PETG?  

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Chris P
(@chris-p-4)
Eminent Member
Is the MK4 to fast or to hot for PETG?

so, I've used a rol of Prusament PETG, the small one that came with the MK4 upgrade...and printed the parts on the MK3S+, flawless as ever...

then I assembled the MK4...and printed a Z-corner piece for testing purposes...

well...the left one was printed on the MK3S+ and the right one was printed on the MK4, default PETG prusament settings, 20mm quality with original Prusa MK4 0.4 nozzle settings...

Why the stringing? Is the MK4 to hot or to fast? are the retraction settings not correct? what's happening...this was not te result I was expecting...

This topic was modified 3 months ago by Chris P
Posted : 20/11/2023 2:39 pm
Krisjanis
(@krisjanis)
Member
RE: Is the MK4 to fast or to hot for PETG?

I see the same thing - but I am in a slightly different boat, I still have my MK3S+ right beside MK4. The parts printed on the slowest 0.20mm STRUCTURAL on MK4 show heavy stringing. The same roll of filament, the same day, the same conditions, the same moon phase, on MK3S+ - string-free. Yes, the crappy parts come out almost 2x faster, but the price is not acceptable to me.

I reduced the stringing somewhat by increasing retraction, which is crazy low by default on MK4 for PETG, but still far from happy. I see Nextruder nozzles "oozing" both on MK4 and XL - by "oozing" I mean that after, for example, loading the filament, it just keeps on coming out long after the motor has stopped. So it might be the heat is going much deeper into the nozzle there and even more extreme retraction is needed.

Posted : 22/11/2023 7:43 am
PDG liked
S8ang@
(@s8ang)
Member
RE:

I am having the same issue. My mk4 printed fine with the PLA that came with the printer, but when I am trying to print in PETG I can't get acceptable results. I just tried to print a temperature and bridging tower with terrible results on every level.

I tried playing with the settings, upping the rectraction, but nothing helps with stringing and blobbing. 

I downloaded the G-code from printable, specifically for the MK4. I didn't slice it myself, so it shouldn't be any setting I may have messed up.

 

Please Help if you have figured this out. I thought the Prusa would have been easier to figure out. What do you do when you cant get good results in test prints?

 

Thanks

This post was modified 3 months ago by S8ang@
Posted : 22/11/2023 8:24 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Is the MK4 to fast or to hot for PETG?

did the printer acutaly change temperatures at the set points for each sample?

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 22/11/2023 8:30 pm
S8ang@
(@s8ang)
Member
RE:

Is there a way to check in the G code? I wasn't paying attention when it was printing to see if it actually changed temperatures.

 

(edit) I did figure out how to open the G code to verify that there was instructions to change the temp, but i did not physically witness it when it was printing.

 

This post was modified 3 months ago 2 times by S8ang@
Posted : 22/11/2023 8:41 pm
OWLicious
(@owlicious)
Member
RE: Is the MK4 to fast or to hot for PETG?

Hello everybody,
I have exctatly the same problem and during the weekend i tried/tuning something and now is better.
The work is always in progress but now i reduce a lot the the stringing without change the temperature.
In fact i used the "ramp"  parameter (new param in prusaslicer 2.7) like the xl and increase the rectartction speed and lengh
if i can help you i share to you my logbook 

Posted : 28/11/2023 5:36 pm
Wilmheath
(@wilmheath)
Eminent Member
RE: Is the MK4 to fast or to hot for PETG?

Just making sure, you all are printing with IS? If so then yes, I've had nonstop issues printing with PETG and IS enabled.

Posted : 29/11/2023 3:28 pm
S8ang@
(@s8ang)
Member
RE: Is the MK4 to fast or to hot for PETG?

What is "IS"?

Posted : 29/11/2023 3:35 pm
Chris P
(@chris-p-4)
Eminent Member
Topic starter answered:
RE:

No; input shaper off…

but Prusa support kindly provided me with a new thermistor; and it prints like a dream! Even better then my MK3S+ I would think…

 

it printed also fine with the previous thermistor, only had to lower the temps by 50 degrees…

This post was modified 3 months ago by Chris P
Posted : 29/11/2023 3:44 pm
JMH714
(@jmh714-2)
Trusted Member
RE: Is the MK4 to fast or to hot for PETG?

 

Posted by: @chris-p-4

No; input shaper off…

but Prusa support kindly provided me with a new thermistor; and it prints like a dream! Even better then my MK3S+ I would think…

 

it printed also fine with the previous thermistor, only had to lower the temps by 50 degrees…

Is that one: https://www.prusa3d.com/product/thermistor-ntc-100k-90-mm/

Posted : 10/12/2023 6:37 am
Chris P
(@chris-p-4)
Eminent Member
Topic starter answered:
RE: Is the MK4 to fast or to hot for PETG?

 

Posted by: @jmh714-2

 

Posted by: @chris-p-4

No; input shaper off…

but Prusa support kindly provided me with a new thermistor; and it prints like a dream! Even better then my MK3S+ I would think…

 

it printed also fine with the previous thermistor, only had to lower the temps by 50 degrees…

Is that one: https://www.prusa3d.com/product/thermistor-ntc-100k-90-mm/

Yes; that is the one ☝️ 

Posted : 10/12/2023 8:03 am
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