I am having one of THOSE moments where i seriously consider throwing out the

I am having one of THOSE moments where i seriously consider throwing out the 3d printer out through the window.

For the X:th time it have stopped extruding mid print in a X:h long print. I now have to disassemble the hotend and clean out the plastic.

The reason? my hotend cooling fan is controlled from RAMPS and is shut off for some reason now and then… this time i will connect the fan directly to the 12v power supply…

And as an added benefit, the cap of the “bowden tube lock” came off and one of the wires/pins on my thermistor broke while i tried to remove the “bowden tube lock”…

Hopefully i will get it back together later tonight, right now i need to releax with a beer and a movie to calm down…

Have anyone had simular problems with fans stopping mid print? My gcode files starts with “M106 S255; start fan” , but i have to manually push the “fan on” button from Octoprint to keep the fan on.

I have never had any problems with prints < 45min, even if i print several of items in serial without cooling down hotend/heatbed…

I wired my hotend cooling fan directly to the power supply. I connect the print cooling fan to D9 on the ramps and let it control that fan.

Extruder fans should generally be connected directly to the supply voltage. They will need the fan to remain on after a print to assist with cooling without heat creeping up into the “cold zone”.
The fan control in slicers, and the fan connection on control boards, is meant for a part-cooling fan.

Unlike many people here, the fan should not connect directly to the power supply. The firmware has an option for a hot end fan pin, and a temperature at which it should turn on. This allows you to always have the fan on while printing, but not prematurely wear it out after a print is finished.  Just set the fan pin to the same logical pin as d9

You will find the relevant settings in configuration_adv.h

@ThantiK Thanks, will take a closer look on that :wink: that is probably something i missed during the original assembly. The instructions was not that good.

I am constantly learning from you!

I used to have my fan connected to the hotend, but after I got my PID tuned really good it would shut off and on so fast the fan never spun up and started clogging all my jobs. It probably would have been smarter to hook it straight to the supply voltage, but I ended up using the print cooling supply. I only print in ABS so I never use a fan there anyway. Then I have my cooling settings to be always on from layer 0 up. That way it’s on during raft when I use one.

@ThantiK Or the way I have mine is to wire the fan to constant 12v from the PSU and just have the RAMPS turn off the PSU (via the ps_on pin) once the hot end has cooled down. That way all the fans are on when the printer is on, when the printer isn’t printing there are no fans on, hot end, part cooling or RAMPS fan. All of them are off. Nice and quiet.

Good news, I am up and running again! Wired it directly to the 12v supply. When I turn off the lights in the room with the 3d printer in it, the power supply for the wall outlet gets cut as well, a bit annoying, but in this case useful.