I recently got into 3D printing by building the Folgertech Kossel 2020 Rev B kit and had gotten it working fairly decently. After a brief hiatus during which I installed some new parts (E3D volcano hotend/heater cartridge, new thermistor) I was able to get the printer working well again. However, recently I’ve been having some prohibitive problems:
-Midway through prints, the printer has been suddenly stopping. Additionally, after killing the print and trying to run a G28 command, it would not perform the command properly, though turning the printer off entirely will allow it to execute basic commands (but not prints). I’ve tried everything from different USB cables, running prints from an SD card, isolating the printer’s power supply, different printing softwares (Cura, Pronterface), etc. and nothing has fixed the problem. I never used to have this problem, and it just suddenly started cutting out midway through prints.
-My other main problem is with the PID heating. I’ve run the auto-tune several times (more than I care to count) and have re-uploaded to the board. However, when PID is enabled the hotend will heat up to within five degrees of the target and then fluctuate between fifteen and five degrees below the target. I’ve tried re-auto-tuning, manually changing K (p/i/d) values, using default values, etc. and again, nothing has worked. The hotend heats up fine, and I am able to print using Bang-Bang mode normally, it’s just the PID system that doesn’t seem to be working properly.
The Kossel runs off of Marlin, if that helps at all.
Since you have already changed the usb cable i assume you are now using one of a better quality and not the one tha comes with the arduino kit.check if any of your nema motors gets hot after some time.
My assumption is that you have a thermal runaway for the hotend.
Did you modified the thermistor type in the firmware after the hotend replacement ?
Are you sure the thermistor is mounted correctly into the hole in the heater block? Did you put some heat paste into the hole before inserting the thermistor?
If all of the above done correctly and the thermistor’s legs don’t short each other try to replace it with a new one.
Also my advice is the replace the current thermistor with a screw in one modifying the heater block these types don’t fail so often that small glass encapsulated ones:
Hey, I had similar issues to the midway stops. It was because of the safety temperature control. If the temp doesnt change for a certain amount of time, printer halts to avoid accidental overheating. I increased the time limit, for it to 60 seconds or so. I think its in Config_adv.h Regarding to the pid issues: have you set the right thermistor type for your hotend? If I remember correctly, for e3d it’s 5. Another possibility, if your marlin version is a bit old, and it’s worths to upgrade. Check out on their github repo. Hope this helps, Cheers
Id try reloading the firmware and putting a fan on your printer electronics tho it does seem the issue is the PID. The firmware reload you’ll need the calibration settings written down but starting from scratch usually kills grimlins
I’d have to agree with Eric_7. This sounds like some weird firmware issue. If you’ve changed some EEPROM settings, record those in your configuration.h file and re-flash the firmware. Marlin has protections built in for runaway or disconnected thermistor issues, at least in newer versions. If that’s the case, it should be throwing errors to whatever you’re using to connect (Pronterface, Octoprint, etc). You might also check the baud rate settings in Marlin and the printer interface to ensure that they match up. 250000 is best, but I’ve heard some linux systems may have issues with that setting unless you’ve installed something to account for this. If you’re using a lower baud rate you can get weird jitters and pauses that sound like maybe mimic what you have going on.
First, I would use an oscilloscope to look for noise in the power supply and possible intermittent wire connections.
Second, I would guess that the wire to the hotend heater is breaking and that the firmware is noticing the strange temperature fluctuations and shutting down to prevent a fire. If that’s right, I would replace the heater wire.
Third, I would guess that the thermistor isn’t mounted properly, leading to fluctuations in the temperature measurement and a protective shutdown.
If you don’t have an oscilloscope (there are good old analog ones on ebay), you need at least a multimeter to diagnose problems like these.
