RE: MK4 PLA Stringing
The first thought might be this way (stringing is only caused by filament and/or slicer), but there a dozens of people having exact (!) the same experience. Me too - I have a absolute fine working, well set-up MK3S+, use only Prusament most times, stored in a special case with dryer and constant humidity < 30% RH.
When I take one of my hundred times printed STLs, use Prusaslice without any changes to the default settings, print it with my MK3S+, it comes out simply perfect. No stringing, no artifacts, nothing. Just good. Used 0.2mm QUALITY setting.The same Prusaslicer (currently 2.6.1), MK4 default setting, 0.2mm Quality profile, same STL, same steelsheet, same filament roll. Print it on the MK4 and get stringing at some points very heavily. The print itself is okay, no layer shifts, no blobs, no under-/over-extrusion. But the stringing is annoying and, for example, when you have a hole in a wall at the model, the layers interrupted by the hole have some artifacts. Not even bold, but in comparison to my MK3S+ good to see.I´ve tested three different Prusa nozzle (2x 0.4, 1x 0.6), same results. Firmware 4.7.2. without any changes.
A lot of users with the same setup, found here, or in the Facebook groups, report the same. So I´m pretty sure there is an issue, maybe only software, maybe firmware, ....
RE: MK4 PLA Stringing
Update the printer to 5.0.0 firmware and lower the temp to 190ºC and it's almost gone the stringing problem, not 100% but much better.
RE: MK4 PLA Stringing
The first thought might be this way (stringing is only caused by filament and/or slicer), but there a dozens of people having exact (!) the same experience. Me too - I have a absolute fine working, well set-up MK3S+, use only Prusament most times, stored in a special case with dryer and constant humidity < 30% RH.
When I take one of my hundred times printed STLs, use Prusaslice without any changes to the default settings, print it with my MK3S+, it comes out simply perfect. No stringing, no artifacts, nothing. Just good. Used 0.2mm QUALITY setting.The same Prusaslicer (currently 2.6.1), MK4 default setting, 0.2mm Quality profile, same STL, same steelsheet, same filament roll. Print it on the MK4 and get stringing at some points very heavily. The print itself is okay, no layer shifts, no blobs, no under-/over-extrusion. But the stringing is annoying and, for example, when you have a hole in a wall at the model, the layers interrupted by the hole have some artifacts. Not even bold, but in comparison to my MK3S+ good to see.I´ve tested three different Prusa nozzle (2x 0.4, 1x 0.6), same results. Firmware 4.7.2. without any changes.
A lot of users with the same setup, found here, or in the Facebook groups, report the same. So I´m pretty sure there is an issue, maybe only software, maybe firmware, ....
Unfortunately, so far there is no help from Prusa side ;/
RE: MK4 PLA Stringing
I tried some temp-settings today.
Figured out, that when i reduce the temp to 190degrees the stringing is gone (printing with sock, activated in firmware and std-0.4 nozzle).
When starting with 215 degrees there is a lot of stringing.
As well when homing with 170 degrees there is a lot of oozing/stringing. This even that the temp is at 170 degrees locked. Even though i let the printer preheat for around 7 minutes before the homing.
For me it‘s clearly a sign, that the temp at the nozzle is to hot compared to the value on the display.
Does anybody have a MK3s to test the file and print it with std prusa-slicer settings?
RE: MK4 PLA Stringing
Mines oozes so much the bed leveling fails very often.
But when I do temp towers, at 190, there’s clear under extrusion and layer adhesion issues.
RE: MK4 PLA Stringing
Please attach the file, and i will try with both printers (MK3s and Mk4)
I tried some temp-settings today.
Figured out, that when i reduce the temp to 190degrees the stringing is gone (printing with sock, activated in firmware and std-0.4 nozzle).
When starting with 215 degrees there is a lot of stringing.
As well when homing with 170 degrees there is a lot of oozing/stringing. This even that the temp is at 170 degrees locked. Even though i let the printer preheat for around 7 minutes before the homing.
For me it‘s clearly a sign, that the temp at the nozzle is to hot compared to the value on the display.
Does anybody have a MK3s to test the file and print it with std prusa-slicer settings?
RE: MK4 PLA Stringing
For me it‘s clearly a sign, that the temp at the nozzle is to hot compared to the value on the display.
If you have such doubts snd evidence then there is the possibility that the temp sensor on the hot-end is out of spec. Its a simple thing to change. Order a new set of temp sensor, heat block and heater cartridge and change it over !
If you speak nicely to PS there even the possibility to swap it under warranty.
RE: MK4 PLA Stringing
Please attach the file, and i will try with both printers (MK3s and Mk4)
I attached the 3mf-Files for both printer.
If you could print it and send me the pictures i will try to contact Prusa Support again.
Hopefully they find a solution then.
RE: MK4 PLA Stringing
If you have such doubts snd evidence then there is the possibility that the temp sensor on the hot-end is out of spec. Its a simple thing to change. Order a new set of temp sensor, heat block and heater cartridge and change it over !
If you speak nicely to PS there even the possibility to swap it under warranty.
I tried it already, but they wanted a comparison between the MK3s and MK4 and i couldn't provide them as i unfortunately sold my MK3s before i realised the stinging issue... 😢
RE: MK4 PLA Stringing
Mines oozes so much the bed leveling fails very often.
But when I do temp towers, at 190, there’s clear under extrusion and layer adhesion issues.
Do you have a picture of the underextrusion?
I couldn't figure out some weakness in the testfile after printing with 190 degrees. It was even pretty hard to break the towers in pieces.
RE:
Did anyone tried to increase the heatbreak cooling increasing the heatbreak fan speed?
The nozzle/ heatbreak construction of MK3 and MK4 are different.
MK3 nozzle and AL heatbreak are connected indirectly via the AL heatblock where the filament is shielded by PTFE tube from the heatbreak. The filament has a chance to stay solid above the nozzle. So, the retraction can work efficiently.
The MK4 filament runs through metal tube (fixed to nozzle) the whole way to the extruder gears with no shielding by any ptfe tube. If the connection between the heatbreak module and the copper part of the nozzle tube, the tube is not cooled properly, so the filament can start to melt before it enters the nozzle. It can result inthe larger oozing and the retraction being less efficient. If that is the case, then there is some issue of the MK4 nozzle HW design and there will be a difficult way to avoid the stringing.
RE: MK4 PLA Stringing
Sounds like a great hypothesis, but fails on the fact most are having little or no problem. including me.
Also I think there is some misunderstanding evident in the quoted post on the theory of how the Nextruder hot-end system is designed to function.
The whole of the long metal tube acts as a “heat break”, cooled by firstly the heat sink and secondly by the hot-end fan (on the front of the extruder). The key is in the material that tube is made from, which would be a metal having higher heat resistance. Its all about control of the rate of heat dissipation. The tube will have a gradient of heat from bottom to top.
Also key are the two knurled screws holding the tube in place. If not tightened correctly then heat transmission from the tube to the heat sink will be less efficient. Also look at the heat sink itself ensure it has nothing impeding air flow.
So, to those having this issue I suggest investigate installation of the hot-end into the extruder and check that its fully inserted and secured properly by the two knurled screws. (When I checked mine, I found the top one was slightly loose.)
Did anyone tried to increase the heatbreak cooling increasing the heatbreak fan speed?
The nozzle/ heatbreak construction of MK3 and MK4 are different.
MK3 nozzle and AL heatbreak are connected indirectly via the AL heatblock where the filament is shielded by PTFE tube from the heatbreak. The filament has a chance to stay solid above the nozzle. So, the retraction can work efficiently.
The MK4 filament runs through metal tube (fixed to nozzle) the whole way to the extruder gears with no shielding by any ptfe tube. If the connection between the heatbreak module and the copper part of the nozzle tube, the tube is not cooled properly, so the filament can start to melt before it enters the nozzle. It can result inthe larger oozing and the retraction being less efficient. If that is the case, then there is some issue of the MK4 nozzle HW design and there will be a difficult way to avoid the stringing.
RE:
I am sure the temperature gradient inside of the mk3 ptfe tube will be bigger than the gradient inside of the mk4 metal tube, rgardless it has higher temperature resistance than the copper nozzle.
Bryn51 I agree with you that the two knurled screws must be correctly tightened. Nevertheless the quiet from prusa side does not give a good impression. Your mk4 printing a temperature tower does not do any stringings?
RE: MK4 PLA Stringing
Well, it seems that *something* has been improved...
Today I´ve installed the new 5.0.0 release firmware at my MK4. After updating I´ve perform a factory reset, doing all tests again, works fine.
Now I´ve printed a temp tower using Prusament PLA and standard profile for MK4 Input Shaper "SPEED" with 0.2mm layer height. I´m very happy about the result at the very first try:
210 degrees looks good for this template using Prusament PLA.
RE: MK4 PLA Stringing
This picture is all I kept. The 190 part of the tower separated as I was flexing the bed sheet to remove the print.
Mines oozes so much the bed leveling fails very often.
But when I do temp towers, at 190, there’s clear under extrusion and layer adhesion issues.
Do you have a picture of the underextrusion?
I couldn't figure out some weakness in the testfile after printing with 190 degrees. It was even pretty hard to break the towers in pieces.
RE: MK4 PLA Stringing
Hi @tfhh
Great to hear! As soon as I am at the printer I will upgrade and run the test. Did you import also new print profiles? They also contain retract parameters which could influence the stringing.
I look forward to hear other positive replies.
RE: MK4 PLA Stringing
Hi @tfhh
Great to hear! As soon as I am at the printer I will upgrade and run the test. Did you import also new print profiles? They also contain retract parameters which could influence the stringing.
Yes, to be sure that no old components may disturb anything, I´ve also cleaned up my Prusaslicer installation. After firmware update and factory reset of my MK4 I also de-install the Prusaslicer, manually delete all remaining directories with *prusa* in their name, let run a registry cleaner and reboot Windows. Install 2.6.1 fresh with all its defaults. Didn´t change anything to the profiles and templates - just print 🙂
RE: MK4 PLA Stringing
Halo vyresil jsem silikonovym navlekem a strigovani je pryc.....
Super....
RE: MK4 PLA Stringing
Already went through with support first we changed Thermistor, last week i got a new nozzle, but no change at all. Print quality is still SHIT.
It must be a Hardware Design Flaw, it is really disappointing. Should have kept my MK3S and never order this Beta MK4 Printer.
Will try the new FW today but don't think this solves the Problem.
If Prusa is unable to solve it soon i will sell it and move away from this brand for ever.
RE: MK4 PLA Stringing
this is a peer to peer forum,
Prusa rarely look here
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