I picked the new number 4 Migbot  yesterday,

I picked the new number 4 Migbot yesterday, it was a friend’s but she went and bought an Ultimaker 2. I basically helped set it up, so it’s the same setup as the other 3 apart from the small bed, so dual Layer fans, E3D v6 etc… thing is, and this is me just confirming my thoughts, when both cooling fans are on, I’ve tried various speeds 20-60% and it’s pretty much the same, so I don’t think it’s the amount of airflow over the bed, the bed temperature plummets and causes a thermal runaway. However, if you stop one fan manually by putting a finger on it, the temp is fine. My thoughts are it’s drawing too much current for the PSU causing the temps to drop, would this be correct?

As a note, the power wires on the bed are still stock and are under-gauge, I’m thinking this could also be a contributing factor.


Ok, worked it out with a little help, seems the fans are pushing more air than my other 3 combine that with a purely glass bed it’s causing things to go haywire, going to have to start the fans later to combat this.

I had thermal runaway later in print too, when my fan wasn’t mounted firmly and after some time its weight bend the mount and started blowing more on heating block then on printed object.
Try to reduce power that goes to fan either with potentiometer or firmware if connected to some controlled output. Some fans blow more air with same voltage then others - that is what I learned too.