Non-constant temperature

[niek20 0]

Hello,

I've my Ultimaker for three months now and made already a lot of good prints.

Only since last week i have problems with the temperature in Cura. The temperature wont get constant anymore. It fluctuates constant around the set temperature, like a sinus wave. The difference is always around the 20 degrees Celcius. I've already re-installed the firmware and Cura, but this didn't help. Hope someone can help me with this problem.

Regards,

Niek

 

[nick-foley 4]

Double check the integrity of your thermocouple wires, particularly where they connect to the printhead PCB and where that PCB connects to the cable assembly. Also check that the transition from the metal housing of the thermocouple to the wire mesh sleeve of the thermocouple looks good.

I had a similar problem a few weeks ago and one of those connections was starting to come loose.

 

[SandervG 1,018]

I agree, most likely the iron cover of your thermocouple started wearing off, and now it is reading the temperature just outside of the aluminum heater block, where it is slightly colder. Hence the lower temperature.

Have you recently had to disassemble your hot end, or remove the thermocouple by chance?

 

[aaron 2]

Drafts or air from the fan may be causing heat to dissipate from the hot end inconsistently thus creating a situation where the thermocouple cannot keep up with the changing temperature. It is unlikely this is the problem but I hope this helps a little if any.

 

[niek20 0]

Thanks guys,

The problem was definitely in the thermocouple. The wires inside the thermocouple were slightly moved.

It's fixed now and running again wihtout problems.