Partially Solved Hot End Cooling Fan Control Question

So, I have found an interesting problem that I think I understand, but don't know how to fix.

I am printing a large part. I just printed the first half yesterday and it worked ok. The quality of the edges are, I believe, due to to export setting on my solid model. I have fixed it.

So: here's my problem. I'm using MatterControl (which may be part of the problem). I am using Slic3r to make my gcodes.

I do not know how to control my hot end fan. If I use MC to preheat my extruder and bed, my fan never turns on. This results in a great first layer until the cool end heats up to the point where the material gets soft and then last third of the first later fails.

I'm cooling off the hot end now. I will retry the print but without preheating the extruder at all. That seemed to work last time.

 

OK. So the fan turned on by itself and so I'm going to let it go. Don't know what the problem is, but apperently there is no controller, it just is powered directly from the power supply. Interesting.

 

Thanks Jerry,

I just sent in a request, but I forgot to include the photo since the printer is going. Once it stops, I'll send you a photo if you can PM me your email address.

paul