Hotend and bed thermistor range Creality cr-10

[wrenchmeister]

Hi, I have had a cr-10 for about a week now, and have been very impressed with my first 3d printer.
To get away from the noise, I have relocated it to my outside unheated shed.

I did a print last night, and when it was finished I went to remove the part and saw the minimum temp error. Didn't think much of it, but this morning I tried to run another print but it wouldn't let me because of the same error. Both bed and nozzle temps were reading 0 degrees C. Ambient temp was right around 0C.

I am assuming it is a failsafe, and that the controller must see a minimum temp somewhere above 0C before it will try to run the heaters.

Does anyone know the minimum accurate reading of these thermistors? I'm wondering if I can change the firmware to allow for a minimum temp of -5 C or so.

Thanks.

[Trakyan]

Yes, it is a failsafe. Usually a low temperature reading like that means the thermistor has broken a wire or disconnected. If the printer tried heating the hotend with a broken thermistor, it would try heat it, see no change, try heat it, rinse and repeat and the hotend would end up melting the aluminium block while the printer thinks it's cold. I don't recommend bypassing this setting, it can be dangerous especially with cheaper chinese kits where quality control is minimal. That and printing at 0 degrees ambient will give you warping and delamination issues.

From what I'm aware, most thermistors used in 3d printers aren't very accurate at low temperatures (or exceedingly high ones, but they should be good for anything you'd actually want you hotend to reach). I haven't heard of anyone trying to use them in the negatives.

[wrenchmeister]

Thanks.. Sounds like I should just build an enclosure and keep it inside.

Thanks again.

[Trakyan]

Out of curiosity, what's the noise issue? The CR-10 uses rollers on extrusions, much quieter than the standard LM8UU+smooth rod.

[wrenchmeister]

I hear most people complaining about the fans in the control box, but on mine the two fans on the extruder are the loudest things. I am looking around for quieter fans, and have ordered damper mounts for the steppers to see what difference they make.

I will still build an enclosure, and after reading more about it, probably a fire detection/suppression system also. I would like to be able to trust it 100% while I am away.