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MK4 PLA Stringing  

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neale
(@neale-2)
Active Member
RE: MK4 PLA Stringing

It seems like it's the hotend thermistor. I kept getting little dots on the bed where it was probing, but the probe temperature is 170°: PLA shouldn't melt at 170.

I created a small temperature tower model, to do some quick tests without using a lot of filament, and confirmed that I can print PLA with the hotend temperature set to 170°. I'm printing Creality PLA which seemed normal on the Ender 3. On my Mk4, the sweet spot for PLA seems to be around 175°.


If you'd like to try your own test, I uploaded gcode files on Printables. Here's how to run your own test:

  1. Go to Small Parametric Temperature Tower and download the "thermistor test" gcode.
  2. Send it to your Mk4 with the input shaping firmware.
  3. Watch it print, and cancel the print when the extruder stops pushing out plastic.
  4. The topmost completed segment is the lowest temperature you can print. It should be 180 or 190, I think.

It would be nice if the firmware had a way to calibrate the sensor: a temperature adjustment offset seems like it could help here. At this point, though, I can work around whatever the issue is by setting my filament temperature to 175.

Posted : 26/11/2023 5:02 am
Jan Hrubý
(@jan-hruby)
Active Member
RE: MK4 PLA Stringing

Few minutes of chat. 

Posted by: @whuazu

How long did it take until they said that they are going to send a new one? Waiting a week now for a reply:/

 

Posted : 26/11/2023 6:37 am
Uranday
(@uranday)
Eminent Member
RE: MK4 PLA Stringing

Because I wanted a second full hotend for easy switching I ordered a full set. It arrived yesterday, it was also black. I will test it later today to see if it is working. Keep u posted.

Posted : 26/11/2023 9:43 am
Rui Cook
(@rui-cook)
Active Member
RE: MK4 PLA Stringing

One more with the stringing problem. Tried everything and also with support. 

Trying to print a Prusacaster and the hexagon parts are a mess. I am using Filament PM.

The support agent told almost immediately to lower the temperature 15º from the 215 i told him, so they know something is not right. 

I'm going to do another test and charge again on support. 

I think everyone needs to do this (if they have the problem) so a fix is pushed.

Posted : 26/11/2023 11:16 am
Jan Hrubý
(@jan-hruby)
Active Member
RE: MK4 PLA Stringing

Yeah lowering temp by 20 helps me a lot. Tested with pla and petg. I suggest everyone to try it. It is still not perfect but it helps a lot. Ať least i can print untill fix is aviable.

Posted : 26/11/2023 11:23 am
Whuazu
(@whuazu)
Active Member
RE: MK4 PLA Stringing

Lowered it by 30. I print now witb 180 and nearly no stringing and so far no more layer shifts

Posted : 26/11/2023 11:57 am
Uranday
(@uranday)
Eminent Member
RE: MK4 PLA Stringing

My result printing prusament galaxy black at 170 on the new thermistor (black)

Posted : 26/11/2023 2:27 pm
Mitch liked
Whuazu
(@whuazu)
Active Member
RE: MK4 PLA Stringing

So a new thermistor is not the solution?:( 

Posted : 26/11/2023 2:28 pm
Rui Cook
(@rui-cook)
Active Member
RE: MK4 PLA Stringing

Printed at 195 from 215 and it's almost perfect. It's a Prusacaster piece in Red Pearl PLA (Filament PM).

The quality is perfect and the stringing practically gone.

Posted : 26/11/2023 2:59 pm
Uranday
(@uranday)
Eminent Member
RE: MK4 PLA Stringing

Did you change anything else? 

Posted : 26/11/2023 3:01 pm
Rui Cook
(@rui-cook)
Active Member
RE: MK4 PLA Stringing

No, just the temperature. 

Posted : 26/11/2023 3:09 pm
Cstef
(@cstef)
Eminent Member
RE: MK4 PLA Stringing

New firmware didn‘t helped for me. 

But had another chat with PS and they sent me as well a new thermistor. 
should arrive on friday and will test it afterwards and let you know.

Posted : 27/11/2023 7:43 pm
neale
(@neale-2)
Active Member
RE: MK4 PLA Stringing

I'm starting to think the printer is fine, and I just haven't dialed in my filament yet.

Posted : 27/11/2023 9:38 pm
mariadumitruiulian
(@mariadumitruiulian)
Active Member
RE: MK4 PLA Stringing

Anyone actually solved the temperature problem?

I was offered the XL thermistor until they find a final problem, but I have doubts that this will solve the problem.

Posted : 28/11/2023 11:28 am
wburkett1965
(@wburkett1965)
Active Member
RE: MK4 PLA Stringing

No change here with any firmware or PrusaSlicer version. I think most people here are just using a temp in the 190 range and are living with it until a real fix arrives. Mine definitely seems like it is hot. When I tried to run PETG out of it the filament was still oozing out the nozzle when it cooled down for the bed level. Leveling even failed a couple of times before it went. I came from an MK3+ with a Dragon Hotend and when I did a temp tower with that it would look great from 200 to 215, so this is a bit off to say the least. 

Posted by: @mariadumitruiulian

Anyone actually solved the temperature problem?

I was offered the XL thermistor until they find a final problem, but I have doubts that this will solve the problem.

 

Posted : 28/11/2023 2:52 pm
Jan Hrubý
(@jan-hruby)
Active Member
RE: MK4 PLA Stringing

New thermistor from support came in today. I have spool of prusament galaxy black pla so i will do some testing now with default profiles and i will report back. 

Posted : 28/11/2023 3:44 pm
Rui Cook
(@rui-cook)
Active Member
RE: MK4 PLA Stringing

Thanks! We will wait for your experience.

Posted : 28/11/2023 3:51 pm
Jan Hrubý
(@jan-hruby)
Active Member
RE: MK4 PLA Stringing

Ok guys listen up i have some news for you!

New sensor is definetly from Prusa XL. Same markings on package, same lenght. 

I have made test with old sensor and then same gcode with XL sensor. My old sensor was black cable one. 

With old (black one) there is really bad stringing. With new (XL one) there is almost not a single string. For me this solved the issue!

I will say that with new one printer is heating up little bit faster. But this is my feeling as i have not measured heating time. 

I will pull photos fom mobile and post them here in a minute but i was too exited about this to not to share with you guys.

Posted : 28/11/2023 4:33 pm
Rui Cook liked
Jan Hrubý
(@jan-hruby)
Active Member
RE: MK4 PLA Stringing

OK here are the photos. 

You can see two thermistors are different. Longer one from XL worked for me. 

 

On the stringing test. Right one is printed with XL thermistor.

Posted : 28/11/2023 4:39 pm
dzajonc liked
Whuazu
(@whuazu)
Active Member
RE: MK4 PLA Stringing

They are sending me a new thermistor. Don’t know which one. Hopefully it will solve my problems too

Posted : 28/11/2023 6:00 pm
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