I was having big problems with the thermistor cartridges for my e3d, I was getting wild temperature swings during printing, bouts of max temp shutdowns, etc. So I bought the type k thermocouple and the board from Filastruder. I installed that and while the temperatures are usable and I'm able to print, the temperature swings are about +/- 2 degrees meaning a range of 4 degrees. Even when the printer is idle, and not printing anything, I'm still getting variations in temperature. I've changed out every piece of the electronics and the printer itself has been completely rebuilt and now uses a Titan extruder with the e3d. I guess my question is this normal behavior for the thermocouple. I was bundling the thermocouple wire with the other wires going to the extruder, but then I saw this Stack Exchange post and I then isolated the thermocouple wire so it doesn't travel anywhere near any of the other wire bundles. The first graph below is when the printer is idle, the 2nd is during printing. There was a time when my hotend was just as rock solid as the bed with only about a +/- .1 degree variance, but I haven't seen that for a long time now.