Heater issue: Heater extruder not heating at expected rate

Hi. So, I been having this issue randomly for some time now and it's driving me crazy at this point. My VCore has been working fine with the Rapido (not UHF) for some time now and I have been able to even print for 40 hours with no issues whatsoever. However, for the past three weeks I haven't been able to print not a single thing because of the verify_heater issue. I can see on the Mainsail graph that once the temperature I use for PETG is reached (245), it randomly ramps down between 20 to 40 degrees and most of the times is not able to catch up and start printing. I have searched around here for this same issue and tried all the options I have found: Redoing PID calibration, changing for loose/broken cables (I even changed cables from another Rapido), changing the thermistor and even replacing the heating cartridge but nothing works, I will always end with this same issue at some point. Usually happens before starting a print, but it also happened mid print multiple times. I have attached both klippy log and printer.cfg. I don't remember changing any config parameter that could break the printer, but at this point I don't know what I'm missing here
No description
13 Replies
flyingonion
flyingonion•15mo ago
For reference: the printer was able to start now a new print, but something's not right with the temps, as it went up to 265 after reaching hotend temp and I can see that there is indeed a lot of stringing and blobs in the printing (see attached picture)
Nebulator
Nebulator•15mo ago
You might want to consider changing the thermistor to another header on the control board
flyingonion
flyingonion•15mo ago
I've just made the change and I'm running again a PID tunning and some more tests after. I will update it with my findings. Thanks for the suggestion. As I have been tinkering with a different board this past weeks I totally forgot that the octopus has 4 slots for thermistors 😄
equal-jade
equal-jade•15mo ago
Hi! I am having similar issues, did the change on the control board work for you @flyingonion ?
flyingonion
flyingonion•15mo ago
I think it fixed it but I cannot confirm yet. After changing the thermistor to another header the pid and the heating seemed to be stable, but I found out that due to the temp rising a lot some of the PETG parts of the hotend support started to melt and led to my hotend crashing against the bed, breaking the heatbreak. I had no time to check this until yestersay and I'm getting a replacement tomorrow. I will try to update as soon as I make the change and see no issue here.
equal-jade
equal-jade•15mo ago
Thanks for the info.
flyingonion
flyingonion•14mo ago
@topchicken6277 I've just made the change on the heatbreak and seems it's working fine now. To verify that it was indeed fixed by changing the header in the board I've kept the thermistor that I had earlier. So now it's not doing strange things with the temps and prints fine. 😄
equal-jade
equal-jade•14mo ago
Thank you! This is going to be a stupid question perhaps but I tried the same and now I get MCU shutdo: ADC out of range error. Do you need to change something in the config?
flyingonion
flyingonion•14mo ago
Yes, you will need to change the sensor_pin in you printer.cfg so it points to the new connected pin in the board
Japroo65
Japroo65•8mo ago
@flyingonion sry but how does it work. To change the pin?
flyingonion
flyingonion•8mo ago
You need to change the sensor pin in your printer.cfg file. Check the datasheet of your board (I have a BTT Octopus), and use the name of the new port where you connected your thermistor. In my case looks like this:
#############################################################################################################
### USER OVERRIDES
### Anything custom you want to add, or RatOS configuration you want to override, do it here.
#############################################################################################################
[extruder]
sensor_pin: PF5
#############################################################################################################
### USER OVERRIDES
### Anything custom you want to add, or RatOS configuration you want to override, do it here.
#############################################################################################################
[extruder]
sensor_pin: PF5
Japroo65
Japroo65•8mo ago
@flyingonion thank you very much :chefkiss: @flyingonion but didnt help still the same error
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