5 hours with tech support and got nowhere on bed temp problem  

RE: 5 hours with tech support and got nowhere on bed temp problem

Bed thermistor needs replacing 

RE: 5 hours with tech support and got nowhere on bed temp problem

Posted by: @hello

Bed thermistor needs replacing 

How to go about making this happen?  Tech support did not suggest or mention this.

RE: 5 hours with tech support and got nowhere on bed temp problem

how old is the printer

Posted by: @daspud

 

Posted by: @hello

Bed thermistor needs replacing 

 

How to go about making this happen?  Tech support did not suggest or mention this.

RE:

just to confirm its a mk4 if it is and mk3 if its less then a year old and under warrenty or its a mk4 get back to live chat with prusa tell them that your bed thermistor is faulty and that it is reading the wrong temps if its more then a year old and mk3/mini and your outside the eu you need to purchse this https://www.prusa3d.com/product/heatbed-thermistor-set-mk3-s-mini/

RE: 5 hours with tech support and got nowhere on bed temp problem

so i just found you posted in the mk4 section so you must have a mk4 unless it was a mistake so contact prusa and let theme know your pretty sure its a faulty bed thermistor

RE: 5 hours with tech support and got nowhere on bed temp problem

No mistake.  MK4 kit 1 month old.  I will try to contact them again.  thanks

Posted by: @hello

so i just found you posted in the mk4 section so you must have a mk4 unless it was a mistake so contact prusa and let theme know your pretty sure its a faulty bed thermistor

 

RE: 5 hours with tech support and got nowhere on bed temp problem

Infrared thermometers need calibration to the emissivity of the surface they are measuring. They can be wildly inaccurate if not calibrated to the surfaces they are trying to read.

Not to say you don't have a bad thermistor, but infrared temperatures are not just a point and shoot. 

Posted by: @daspud

I started having adhesion issues on one particular print so I measured the bed temp because it was acting like it does when you slice for pla and use PETG. 

Temp measured 70c and the display said it was 85c.  The one thing I got from tech was to change the bed temp setting in the slicer.  I set it to 100 and guess what!  The print worked and the bed temp was 85 as measured by my infrared thermometer.

So, what is the real problem and how to fix it?  I am starting to think that maybe the error has been there form the beginning (it is a kit).  I always felt like I had skimpy adhesion but brushed it off.

RE: 5 hours with tech support and got nowhere on bed temp problem

Are you sure your thermometer is reading correctly?

Do you maybe have another device like a multimeter with temperature measurement to verify your value?

RE: 5 hours with tech support and got nowhere on bed temp problem

I took readings as the bed warmed up.  The displayed value and my thermometer value tracked until about 50c then the display kept rising at a faster rate than what I measured.  When I used it on my MK3 the displayed temp and the measured temp were fairly equal.  This is 15c difference.

RE: 5 hours with tech support and got nowhere on bed temp problem

Hi, I just wanted to add something here. I started to see warping on PLA and PETG prints after firmware 5 upgrade (perhaps consistence) but did not had the problem before and print some spools of filament with 4.x firmware on the MK4 without issues.

Anyhow, I checked the bed temperature with a infrared thermometer and guess what, I am 15 to 20 degrees off, depending on where on the sheet or bed I measure. It is getting even worse on higher temps.

So I must assume that the probe works but for whatever reason with the firmware the offset or reading from the software are misinterpreted.

Anyhow, have you gotten your problem fixed?

Thanks

RE:

I'm experiencing the same temperature issues of 20-25C lower than set temperature. Tech support refused to accept my temperature reading from infrared gun even though I measured 3 MK3s as a baseline (all read within 3C of set temp). I also used a thermocouple with multimeter to verify (measured top and bottom of build plate) with the same lower temperature readings of 20-25C. I thought it was just a bad thermistor even though I measured 99Kohms so I ordered a new bed thermistor but this did not fix the issue. I did increase the temperature in slicer to 105C  with successful PETG prints but this should not be a solution as Prusa needs to fix the thermistor values in the firmware unless there are issues with the new Buddy board. 

RE: 5 hours with tech support and got nowhere on bed temp problem

Those thermistors are not a best of class, I would recommend to clime a warranty replacement. 

RE: 5 hours with tech support and got nowhere on bed temp problem

Guys ,°C

which FW version do you use? First I did not believe, but recently measured mine MK4 bed with the below CA 1821 equipped with magnetic probe, and at set temperature of  85°C  I measured a poor 72°C.

This not a thermal camera but precize thermometer.

RE: 5 hours with tech support and got nowhere on bed temp problem

here is the actual picture

RE: 5 hours with tech support and got nowhere on bed temp problem

@hello

did you have a chance to measure your mk4 bed temperatures?

RE:

@daspud

do you know, with whoom did you discuss from support?

Would you talk to him again, tell that they should look into thermistor_2004.h file some of the values are incorrect there.

I will try to change in mine printer to see whether I am correct.

RE: 5 hours with tech support and got nowhere on bed temp problem

@pink_clown I used a thermocouple very similiar to your CA1821 to verify my temperatures as well. Im using the latest firmware 5.1.3. For a set temperature of 85C, my measured temperatures with thermocouple are 65-70C across the buildplate (edges and corners are lower with centers measuring around 68-70C) 

RE: 5 hours with tech support and got nowhere on bed temp problem

Since I have an extra MK4 bed thermistor, I will replace with the MK3 style thermistor by adding the MK4 plug to the MK3 thermistor. Will let you know if its the thermistor style or if the thermistor firmware file needs updated. I'm assuming its the style since they are both 100K thermistors

RE: 5 hours with tech support and got nowhere on bed temp problem

I dont own an mk4 i own an mk3 but am getting the mk3.5 kit which requires the replacement of the thermister so will update what temps mine arw reading .

Posted by: @pink_clown

@hello

did you have a chance to measure your mk4 bed temperatures?