The Eclips3D has two fans: the usual E3D hot end fan, and a layer cooling fan. I was finding that the layer cooling fan was so powerful that the hot end could not keep up when it was running at 100%. I had prints where the temperature of the hot end dropped from 195C all the way down to 130C due to the fan. One way of dealing with this is to set the maximum rate of the fan to 50% or 70%. Another suggestion, from the Eclips3D forums, is to use ceramic tape to insulate the hot end. Amazon sells small amounts of the tape for a cheap price.
The tape cuts easily with scissors or a scalpel and you can wrap it round the heater block and secure it in place with Kapton tape. In my case I wrapped it around so that it would insulate the block from the cooling fan while leaving the ends of the block free. This is good as there isn't much airflow across the ends, and it gives a smooth surface to stick the Kapton to. It looks like this:
Here is the tape before I attached it:
And on the hot end:
(Sorry for the poor picture quality on this one.)
It seems to work quite well in this arrangement. Here is a graph of the temperature in the incident I described before:
And here is a graph from after:
This shows the hot end coming up at 195C with it well away from the bed. At the 11:00 mark, I turned on the fan 100%, with no difference. At 12:30. I moved the Z position to about 1mm, so the backwash from the bed would have an effect. There is a bit of instability, but it did OK.
Finally here is a print of a thin walled cube with the fan at 100%. The print started at the 37:00 mark.
This confirms the dip and recovery for low Z. I will probably still run the fan at a maximum of 70%, except for bridging, so this is a worst (or at least bad) case test. I have not done PID tuning since attaching the tape and I expect it to be more stable afterwards.
I recommend it if you have this problem. It's cheap, easy to apply, and seems to do a good job. Allegedly you can even touch the hot end when it is hot with this tape on it. Shall I try this? No.