Heating failed and thermal runaway

Check your fan height is only 1-2mm above the nozzle (both fans) as that could be cooling the hot end from either side. Also check your fan speed. If it's ABS you are using you shouldn't need the fan or at least only on a little. I suffered with the same issue and eventually it transpired I had a faulty PT100 sensor. Got a new one from support and now it prints like a dream. Although Colorfabb XT is proving to be a touch difficult for me!

 

I don't know a lot about dual extruders as I only have the single pro with Volcano myself..

But when I got that message, it was in conjuction with the fact that the screw piece between the extruder heatsink and the heated brick was loose. I took it apart and then redid my z offset afterwards and everything was good again. Maybe try that? Judging by the picture you posted on G+, i'm assuming the error is coming from the fact that one of your nozzles isn't heating up, nozzle 2 probably. maybe take that one apart, put it back together, redo your z offset and turn down your fans....

if all else fails, maybe a faulty sensor. Best of luck! sorry i'm no help

 

I suppose you printed the Benchy with the gcode provided by E3D (the one on the SD card). Is gcode is a bit overenthusiastic with the fan speed after a certain layer height. This results in a thermal runaway with a lot of people (also with me) because the PID control can't manage the sudden environmental changes (eg the fan going to 100% all of a sudden).

When printing the E3D benchy, I usually manually reduce the fan speed once it's going to full speed. Usually 50-60% will be sufficient.

 

The supplied benchy was sliced to be printed with PLA. If you really want to print with ABS, better don't use this gcode. First print with ABS is no good idea though...

 

Can you take picture of your nozzle and heat sink, and upload it?

 

Also had problems with thermal runaway when testing Colorfabbs HT filament, extruder was running at 260C, and default fan settings. Had to set fan to 10% get it printing without issues, but at 10% it wouldn't start.

Anyone tested whats the lowest speed you can set the fan to and still work?

 

I've noticed that when the fan is too close to the bed it cools the bed down too much. I have also heard that the fan is a beast and 100 percent isn't necessary. If you look at the temperatures when the fan turns on, if the bed drops too fast, you have either turned the fan on too soon, or it is on too high. If the nozzle cools too quick then the fan is set too high and is blowing directly on the nozzle. I think I got my thermal runaway error when the bed dropped 10C and couldn't recover. This is a safety concern so don't turn this off in the firmware or set it to drastically to overcome the error. If the pt100 were to fail and this wasn't set the pt100 could read bad and potentially cause the heater to continuously heat to get up to temperature which could damage stuff.

 

My fan won't spin properly until I set it to 40-50%, and at those speeds it's quite effective. Alot wind around the nozzle

 

In s3d I believe there is an option to blip the fan on to full speed to get it to go and then it will dial it down.

 

As we have two fans, the one clipped on the heat sink and one at the side which fan are we referring to?

 

Longer post to follow but I suspect that my "Thermal runaway" happened after the "print cooling" fan(s) started

 

@Austin : That's the place your head begins at each new layer. You can change this setting in S3D, so that it begins at a random place (I don't know the place by head, and I'm at my work now).

 

As it was my very first print, using the PLA filament provided with the BB kit I set the temp as suggested in the instructions which was 210oC. (this was a print direct from the front panel so no Octoprint or S3D involvement) The print worked with a little lifting off the bed but not sufficient for it to come loose or be hit by the other nozzle.

It's odd that the settings in S3D, OctoPrint etc. for PLA are 190 but this print worked well with PLA at 210. Of course knowing what I know now (apologies to Donald Rumsfeld ) I know now what I didn't know before ! Probably what happened is that the sharp decrease in temp (due to the print cooling fans coming on) that happends when using the default settings in S3D, didn't happen because either the higher temp avoided the sharp dip or the fan control for the "print cooling" fans was different, i.e. not producing the sharp drop in temperature that the S3D default settings produces, ending up with "thermal runaway". Moving the print cooling fans down to within a few mm of the nozzle height did result in a good ish print, but I have yet to try another.

This all suggests that both the fan height and the cooling profile (it can be adjusted layer by layer in S3D, Edit Process Settings --- Cooling) are critical. Unfortunately the build instructions didn't appear to include any suggestion as to the fan height, but they do now. Possibly this should have a mention in several places so as not to be missed.