Automatic Cooling for Wanhoe Duplicator 4

I’ve been testing this automatic fan upgrade for my Duplicator 4 and WOW what an improvement in the quality of life around here. Finally I can just start a print on my Dup 4 and walk away knowing the active cooling fan will start on its own. No more being a slave to the printer. It goes in series with my existing fan circuit and bolts on using hardware already there. It is micro adjustable so you can set it to turn on after a set distance into the print, up to about 5mm or even more if you use a longer M3 bolt in the adjustment mechanism. The fan always turns on at exactly the same distance into the print, not like when I had to do it by hand. I’ve been giving the printer a real workout lately printing inventory for my web store. I think my prints are coming out better than ever, with consistent results. There’s a manual override switch just in case I do need to go back to full manual control.

I always wanted to control my active cooling fan from gcode, but that requires soldering a