3D Printing Forum

I have an issue with my UMO that I didn't notice before (it might not be new, but I never noticed it before).

When I use the fan at a low percentage I cannot get a stable temperature...

I did some test with a print this evening, temperature set to 225°C.

- Fan off: after 2 or 3 oscillations, it sticks on 225°C and doesn't deviate anymore
- Fan 10-20%: it never stabilize jumps between 222 and 228°C!
- Fan 50%: a bit more stable 224-226°C
- Fan 100%: stable at 225°C, no deviation

I may be completely wrong, but I have the impression that the PWM fan influences the sensor.

Anybody already seen that?

(It is an old 1.5.3 board with thermocouple)

The test was done with the bed making the air bounce on the block? I suppose not, so it's really weird I suppose. I know very very little of the 1.5.x boards.

I've only run 100% fan but tonight I plan to try out XT-CF20 with No Fan...I'll see if the temp bounces around

I'm printing now. No fan. Temp set to 256 and seeing it bounce around from 255 to 257. Nothing wider than that so far!

Amedee wrote: Anybody already seen that?

Well, yes. I have that also. I think since the beginning. I just ignored it / accepted that PWM is messing with the sensor. I allways see it at the beginning of prints as the fan slowly starts up... I am pretty sure it's PWM and I assumed this is "normal". I see that because I sometimes have to manually help the fan to start in the beginning ... after the first layers when the fan kicks in fully, no issue.
I have never looked at it in detail... will try to the next print. But I am again off a few days (congress).

Yes, I guess I never noticed before because it is common that when you start the fan the nozzle needs to adjust a bit.
What made me looked more in detail is that nowadays i tend to use very little fan and it stays in the 10-20% range while in the past it would just have been a transition...