FYI, thermistor failed, found set screw was way too tight.
Had the thermistor fail yesterday, luckily after finishing up a print job. Prusa support was awesome with a quick troubleshoot and sending a replacement. Today I pulled out the factory installed thermistor and found the set screw was super tight and had actually smashed the end of it. It's my understanding the set screw should only be barely over finger tight. Threw a spare in and back to printing. Just an FYI and otherwise LOVE this printer!
RE:
The nice thing about this printer is that it's 10x easier to repair than the competition (or at least I think it is). But, definitely the primary cause of thermistor failure is over tightening the grub screws on the heat block. I keep several spares for both heat block and heat sink in my toolbox.
RE: FYI, thermistor failed, found set screw was way too tight.
The nice thing about this printer is that it's 10x easier to repair than the competition (or at least I think it is). But, definitely the primary cause of thermistor failure is over tightening the grub screws on the heat block. I keep several spares for both heat block and heat sink in my toolbox.
It's easy to repair because everything is screw-mounted. It fails relatively often because screws are too tight, too loose, or allow the screwed-down part to be misaligned. 🙄
In a comparable situation, Bambu Labs would probably glue the thermistor in place. In many units it will last a lifetime; if it fails, the repair will be painful or more expensive because a larger module needs to be swapped. I am sure there would be an easy way to get the best of both worlds -- e.g. a little leaf spring that holds the thermistor with a defined pressure -- but apparently none of the manufacturers can be bothered.
RE: FYI, thermistor failed, found set screw was way too tight.
Happened on my first 3d Printer. I assembled it but the hotend came pre-assembled. Worked for a week then failed. Same cause, too tight on the thermister.
RE: FYI, thermistor failed, found set screw was way too tight.
Reminds me. I need to look under the print bed for any screws stuck to the magnets... 🤔
RE: FYI, thermistor failed, found set screw was way too tight.
The nice thing about this printer is that it's 10x easier to repair than the competition (or at least I think it is). But, definitely the primary cause of thermistor failure is over tightening the grub screws on the heat block. I keep several spares for both heat block and heat sink in my toolbox.
Just ordered some spares to keep on hand, good suggestion. Both my MK3s+ and Core One+ had a factory installed thermistor and both of them I've replaced now, both had the dent indicative of overtightening from the assembly line.
RE: FYI, thermistor failed, found set screw was way too tight.
The nice thing about this printer is that it's 10x easier to repair than the competition (or at least I think it is). But, definitely the primary cause of thermistor failure is over tightening the grub screws on the heat block. I keep several spares for both heat block and heat sink in my toolbox.
It's easy to repair because everything is screw-mounted. It fails relatively often because screws are too tight, too loose, or allow the screwed-down part to be misaligned. 🙄
In a comparable situation, Bambu Labs would probably glue the thermistor in place. In many units it will last a lifetime; if it fails, the repair will be painful or more expensive because a larger module needs to be swapped. I am sure there would be an easy way to get the best of both worlds -- e.g. a little leaf spring that holds the thermistor with a defined pressure -- but apparently none of the manufacturers can be bothered.
Yes, some sort of clip, or have the set screw capture the back of the thermistor near the wires would be ideal. Both my MK3s+ and Core One + I've had to replace the thermistor from factory assembled hot ends.
RE:
That's how the thermistor and the heater are held on a Mosquito hotend.