Thermal runaway

Mostly Printed CNC - MPCNC Troubleshooting
1

Good morning,

I’ve been getting thermal runaway errors on many a longer print batches. I have re wired the hotend to get rid of any disconnects, and moved the fan shroud to keep it from cooling the heating block. Is there anything else I should do?

2

I’m printing at around 30mm/s

50mm/s @ 55%

 

3

Not the same, The accelerations don’t always scale properly (if at all). Anything more than 10% I would re-slice.

 

What exact error do you get? What power supply do you have and where did you get it? What control board?

4
  • I'm using a 30a power supply poached from a robo3d r1
  • The board is ramps 1.4 i think the arduino half is atmega2560
  • I'll lower the speed to 30 and try again
  • The error says "thermal runaway detected, please reset""
5
  • I'm using a 30a power supply poached from a robo3d r1
  • The board is ramps 1.4 i think the arduino half is atmega2560
  • I'll lower the speed to 30 and try again
  • The error says "thermal runaway detected, please reset""
6

Has it previously worked?

That could mean a lot of things, it really just means it has been more than 4 degrees off for more than 4 seconds (maybe 20). It could be the hotend or the bed. If you run it from repetier you will know which one has the problem, your fan should not blow on the hot end at all.

7
The error says “thermal runaway detected, please reset

Thermal protection is a blessing and a curse. I used to get the same error when I would pop a glass bed back on my printer fresh out of the freezer after a previous print.

Your AC could also be blowing to cold. I usually run my self built printer marlin/ramps with a hotend fan and no sock on the hotend without any problems. Like the post above me said, it usually takes a rapid temperature change to set of protection.

You could maybe check your psu with a multimeter, but the way that I understand how printer hotstuff works, you shouldn’t be able to overamp unless you maybe have a mosfet issue or something.

What heat bed and hotend are you using? You could also have a bad thermistor…

8

Mine would do that with a bad thermistor as well. If you watch the temperature graph in repetier you can see it start to not keep up, then you’ll get the disconnect error.