Hi guys. Please check my previous post for any background questions, I don’t have it in me to go over everything again.
Long story short, I was having issues with clogging that were being caused by my hotend not reaching the reported temp. After a few days of troubleshooting and diagnosing the motherboard and Klipper settings, I gave up and decided the motherboard was faulty (even though I could not perform any tests to determine in) and bought an SKR mini. I got that all set up, and the printer has been working flawlessly since then.
Until now.
Same exact problem; one print goes perfectly fine, next print, failing to extrude by the 4th layer. I removed the clog, restarted the print, now can’t even extrude the priming line. Fearing the worst, I disassemble the hotend, try hand feeding filament, and once again I am unable to push more than a few centimeters through before it gets clogged up. A probe thermometer reads ~160C while Klipper reports 200C.
What could possibly be happening here? The board is an aftermarket replacement from a completely different company, so I doubt it’s a recurring manufacturer defect, but I have no idea what else can be causing this.
At this point I’ve spent so much time and money trying to fix this printer that I could almost buy a new one, but at this point I’m not convinced even that would solve the problem.
I really, really appreciate the time you’ve taken to try to help me, but I’m positive the hot end not reaching target temp is the issue. If I push filament against the outside of the heat block, it melts at a very slow rate, when it would normally instantly liquefy against the block.
I’ll drop my config file when I get home.
My temp chart, both before and after the issue started again, are near perfect flat lines. PID tuning done on current hardware.
My hotend has a fan blowing on the cooling block, and two part cooling fans.
There are no clogs/ obstructions throughout the hotend. New hardware has been tested (nozzles, heat throats)
Typically I print between 60-120mm/s depending on nozzle size and the model. But not long before the problem started I successfully completed a tower print at 200mm/s with zero issues. It should be noted, though, that once again this is an issue happening outside the realm of print settings.
Super bizarre…
Any chance there’s some mechanical damage to the thermistor? If you’ve rebuilt the hotend a bunch of times it’s really easy to do, I’ve totally reefed down on a setscrew before and flattened one, could lead to it possibly reporting a wrong value, a crack + high vibrations during printing + thermal cycling could lead to it getting worse over time. Sudden shifts to me would suggest a problem with the thermistor itself, especially given the total overhaul you’ve done. As crappy as it is too, if I recall electrical components often follow an early failure pattern where they can have a higher failure rate at beginning of life and then drops off, for the price of thermistor cartridges it’s not a bad idea to keep some on hand just in case.
To make your life easier, Do you have a molex connector at the hotend? A lot of thermistor cartridges come with short leads and a molex connector, makes swapping them so much easier. If you don’t already have some crimpers, Engineer PA-09 is a solid pair that’ll do everything from molex to jst.
Thermistor swap was done a few times on the old board when the same issue was happening. I had 3 of them that I was swapping between.
Currently in there is a pretty nice thermistor that, rather than using a set screen to keep it in place, is actually built in to the end of a set screw; it’s effectively impossible to damage it. Unfortunately, it’s a known-good resistor, my problem lies elsewhere.
Wow yeah, that’s even more annoying then. Last ditch thing to me would be to check the resistance across th0 and compare to thb, I got ~6.28 kohms on both checking a spare board, just super strange this happened so suddenly.
Good call on checking that resistance, didn’t think of that before.
Even more frustrating is it happening twice across two different boards!