After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Hi,
I've been looking around in the forum and www for some time now but could not find helping clues, so here's my pitch to you:
I've been printing gloriously with my i3 mk2s for a few weeks now. Just loaded the latest firmware (3.0.11) and carried out the auto pid tuning. For the nozzle temperature the effect was completely positive (Temperature used to be +-5°C. and is now within 1°C). For the Bed at first it seemed to work just as well. Barely no deviance when heating the bed up to 105°C.
The problems come up when I start a print. For the first minutes, the bed temperature stays stable. But then it rapidly drops. When I'm starting at 105°C it goes below 90°C and the "Bed Thermal Runaway" error stops the print.
I attached a screenshot from about an hour into a print where I changed the target temp of the bed. After staying stable (although always a bit below target temp.) for ~10min it starts dropping again and stays at 95°C max, no matter if the target is 110°C or 95°C.
I already checked:
Correct Wiring
No burnt hookups
Temp Sensor below bed still in place
Temp. stays stable when only preheating nozzle and bed
no changes in location of the printer or ambient temperature
Solution?
I vaguely remember that a wrong integral part (ki) of the PID tuner can lead to a constant offset in the actual signal. But thats not really the case here, since the offset comes up after a stable period. Thus I would guess it's probably not the PID settings, although that's the most dramatic change I made recently. Another change was that I retightened the x and y belts. They weren't tight enough in the first place and I was starting to see some slipping every few print hours. They sound quite stiff now, is it possible that they're too tight?? The y Axis starts moving on its own when I tilt the printer, but for the x axis it takes some force to move it by hand.
Maybe there is a change in the firmware that lowers the amount of provided power for bed heating / overall supplied power? I would have to test with PLA and see if lower temperatures are working better.
Does somebody have similar issues or any idea how I could fix it?
I'm not too comfortable with shooting up the voltage supply up to areas of 14-15V since my setup has been working before the firmware update. When you have a flat tire you dont want to start adjusting the steering mechanism, you just change the flat tire 😀
From the fact, that the printer only starts to struggle when both nozzle and bed are heated AND axes are moving I am concluding there is most probably a weak spot in the power supply chain. I'd be thankful for any hints what I could check next.
I didn't save and could not find default values for the bed PID so please can somebody tell me if those values are in a reasonable scale?
Recv: Kp: 104.65
Recv: Ki: 4.78
Recv: Kd: 572.28
Thanks for your feedback
Marlon
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Following with interest as I recently started experiencing this as well. I did use the M303 E-1 command to Auto-Tune the PID for the bed which might have ironically started the problem.
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Maybe a dumb question, but when you have this issue, do you use the part cooling fan?
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Hi Marlon,
If I'm not mistaken this are the default values for the Bed in the firmware:
BR, Hendrik
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
When it happens for me, it happens only on ABS which I print with the part cooling fan off.
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Maybe a dumb question, but when you have this issue, do you use the part cooling fan?
Also thought about it, but with ABS the fan is off.
Hi Marlon,
If I'm not mistaken this are the default values for the Bed in the firmware:
BR, Hendrik
thanks Hendrik! It seems my kd value is quite a bit smaller than the default, ki and kp are in a similar range. this would mean that a slightly decreasing temperature would not induce as big an increase in heating power as with the higher kd --> kind of explains my problem during printing.
I tried again with the default values but I'm getting the same behaviour.
I played around a bit while printing and it seems like the maximum stable Bed Temperature is about 90°C, see att.
Does anybody have an idea what's to investigate next?
best regards
Marlon
Marlon
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
I would connect a voltmeter to the lines coming from the power supply to fed to heatbed. Then monitor how much it has when the bed is of, when it heats up and then when you have temp drops. It might be that there is a problem with the PSU.
If this is fine, then it is either that the firmware has a bug or the mosfet on the Rambo has issues.
To verify firmware: Upload the firmware with avrdude and set the option to clear the EEPROM. Then your printer has lost all permanent settings: Claibration, Z Adjust, PID values etc etc for sure.
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Hi,
the printer is back to it's normal behaviour. Strangely I cannot say what triggered the change, since all I did was a recalibration of xyz due to transportation.
Thanks for the help Hendrik, I will get back to it if I need it in the future 🙂
best regards
Marlon
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Quick Update: The answer to the problem is both embarrassingly obvious but also a little bit tricky...
I ran into the issue again and now finally found the cause. Thanks to LaPointe for pointing me into the right direction. In contrary to what I wrote before, my part fan was sometimes on with ABS, namely when layer print time is below 25 seconds (paramter set in slic3r).
The problem arises when several things come together
- high bed temperature (e.g. 90°C for PET)
- part cooling fan ON
- part with relatively small surface area (a few cm^2)
- printing in the center of the bed
--> In this case the heating bed cannot provide enough power to compensate the additional forced convective heat loss.
If only one of the above is not the case, the bed temp will stay stable. I realized it when I did the exact same print twice, but one time in the center of the bed (temp falls) and one time just a few cm away from the center (temp stable).
So what actually happens is that the bed temp right above the sensor falls, but the rest of the bed stays stable and in fact gets even hotter when the power supply is trying to get the temp around the sensor back to normal. But still the software will run into the "Bed thermal runaway" error and abort the print.
Of course the point where you see this effect doesn't have to be in the center of the bed, it will be at the spot where the temp sensor is located on the underside of the bed...
You can easily reproduce the effect:
- Set bed Temp to >80°C.
- wait until Temp is stable
- move Extruder manually at z=0mm and for x and y in the center of the bed
- turn on Fan (M106/M107)
- see how bed Temp drops rapidly
- move slightly in x or y --> Temp stabilizes again
- move z up in 1mm steps and wait after each step --> Temp will slowly rise with each step
My Takeaway: If I print small parts with PET or similar filament I always use the slicer to move the model away from the center --> no more problems
I hope this saves some of you some time figuring out this kind of obvious effect.
regards
Marlon
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Great tip! This solved my Bed Thermal Runaway problem when printing a 20mm calibration cube with PETG.
Thanks,
Scott
Scott
MK2S
Bed thermal runaway problem
I was printing away on Sunday on my MK2S and the printer suddenly stopped with a 'Thermal runaway' error?
I am using PLA, I did a reset and preheated for PLA (55 degrees) which seemed ok, started the print again and the temperature started rising until I got the problem again - even though the print bed light was off?
I removed the print bed and everything looked ok - so I plugged it in again and preheated and this time the temperature dropped to 45 degrees and I got the same error - I tried preheating for ABS (100 degrees) and the temperature stopped at 60 degrees for a few minutes and I got the error again?
Is this likely to be a damaged thermistor on the print bed? Is there any way I can check this? With a test meter it shows open circuit.
I should also mention I had upgraded the firmware to 3.1.0-RC1 on Saturday but have printed several things since then successfully.
Any ideas anyone? I don't really want to replace the heat bed when there is a new upgrade coming up - but not until January 🙁
Chris
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
I just had the same problem! Multi material print. Different material types. Got the error halfway through the print. I will try moving the model away from the center. That sounds like the problem. Small part, directly in the center. Thanks for the post
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Same symptoms today! First time! Same setup: PETG, small part, dead center. Another factor is that the room where the printer is located is cooler than usual. Fixed it by moving the print off of the bed center. THANKS!!
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Check the software page and download and update to the 3.1.0 release.
The thermal runaway problem in 3.1.0 RC1 was resolved in 3.1.0 RC2.
regards,
Bill
Tagaytay City, Philippines
Founder member of Philippines Prusa Printer Owners FB Group
Sponsor Pillars of God Academy in Bacoor
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
I currently get bed thermal runaway when trying to PID Autotune my bed.... Not sure what's going on there. Running latest firmware.
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
i upgraded to newest firmware and i'm having bed thermal runaway issues with ABS. i have the fan turned off and after a while during the print the bed just slowly gets colder and then the error comes up. seems to be an issue with this new firmware as never had this issue before.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Im starting to think the same thing. possible firmware issue. I emailed prusa but ive gotten no reply.. Kind of annoying frankly. I have two machines already and planned to buy many more... but if support starts lacking... may have to reconsider. shame.
I was able to re-calibrate my heated bed by starting autotune at 55c and working my way up. starting at 100c always ended in THERMAL RUNAWAY
2nd machine running old firmware has no issues.
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
Hi,
I have the same issue. After the latest firmware and the material update the printer has become useless. You basically need to sit beside the machine because it is so unpredictable. 😡
Same case with ABS, but I also hade problems with PLA, I had to increase the nozzle temp in order for the print to stop clicking.
Regarding ABS, I have tried to print a small piece the entire day, failing constantly!
Trying to find solutions, but nothing from team prusa.
Have tried PID autotune with Pronterface like some other forums have done to similar problems.
The thermo is well placed under.
The room has good temp.
Print 255 C and 100 C Auto Fan ON, if I don,t use the Fan it prints the entire piece but it melts, so no good.
After layer 3 when the fan starts the bed temp drops to 92 and stays there and then I get the thermal runaway error.
I have tried to move the part from the center. still doesn't work. Any other ideas?
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
You don't say if you have an enclosure to keep the local area temp elevated or what the ambient room temperature is.
ABS especially is very sensitive to draughts or temperature variations and will often produce a deformed print as the distance from the bed increases without an enclosure except in a very warm environment. It will also deform on smaller layer sizes without enough time to cool between layers.
I printed a single piece that has a diameter of around 10mm and it deformed at a height of 70mm - I tried again, printing 4 at one time to allow better layer cooling and had success up to 100mm - enough to make a usable print. If I needed to print taller objects I would need an enclosure - even here.
Bill
Tagaytay City, Philippines
Founder member of Philippines Prusa Printer Owners FB Group
Sponsor Pillars of God Academy in Bacoor
Re: After Firmware Update (3.0.11) and auto PID Cylce: Bed Temperature dropping after short time into a print
I've been having numerous bed thermal runaway issues now since this last update.
it happened to me more with ABS however it is happening with PLA also. a couple of my prints failed randomlly.
It isn't the fan. it is like the firmware forgets to check the bed temperature from time to time.
i have an enclosure, and if i use it then the bed thermal runaway is less likely to occur.
i sat and watch it happen once the red led light on the bed stopped flashing and then the bed temp dropped 15C and thermal runway occurred.
i ran the same print again to reproduce it with the enclosure open and the print was successful.
i checked my bed sensor and connectors and everything is correct so something is going wrong with this new firmware 3.1.0 for the mk2s
“One does not simply use a picture as signature on Prusa forumsâ€