Code already exist in firmware for extruder fan??

[AmazingSpanoMan]

Hi there. I have two Metal Simples that work great as long as the print is less than an hour or so long. Anything more than that and the extruder motor begins to overheat and skip steps. I've tried adjusting the POTs numerous times but either it skips like crazy or overheats. There seems to be no sweet spot on either printers. My solution was to run a fan on the extruder and that has been working well and I've been able to do prints for hours without issue. The next step in my adventure leads me to customizing the fan in a way that the printer controls it on its own.

Right now the fan is hardwired to the power supply so it is on all the time when the printer is plugged in. It gets a bit frustrating having to always unplug my printer when I'm not using it. Right now I have no need for a heated bed mod so I got to thinking... Can I reprogram the pin for the heated bed to control a fan? Ideally I would like it to turn on when the hot end hits a certain temp and turn off once it is cooled.This way I know that it will turn on and stay on even after the print is completed for a little to help aid in cooling the stepper. If that isn't possible maybe just have it so it turns on during a print and turns off when it is complete? Maybe it can be controlled in a start and end Gcode?

Just wondering if anyone had any luck with messing with the pins and doing something similar.

Also, are there any free pins that output 12V that can be used instead of the HPB connection? If there is then that can be used which will still leave the HPB connection open for future heated bed mods in the future.

Thanks in advance for any help.

[AmazingSpanoMan]

[AmazingSpanoMan]

OK I know I'm talking to myself right now but I have more info.

I went into the Configuration.h and the Configuration_adv.h and "-1" the heated bed references. In pins.h the Heated bed is set to pin 20 so I changed that to -1 to shut it off and changed the -1 on the code above for the controller fan to pin 20.

My logic says by setting the controller fan pin to 20 and disabling the heatedbed pin I should be able to use one of the 12V connections and pin 20 to control it.

Any thoughts...

[bres55]

I am afraid I don't know enough to help you, but assure you, you are not only talking to yourself. I will be very interested how you get on, in re-assigning the pins. It's amazing how little snippets of information help to build the bigger picture.
Good luck in your endeavour.

[teicher]

[AmazingSpanoMan]

OK so I scanned the code made changes where I think they should be made to change the pin I'm going to test it tonight on one of my metal simple
You can download the hex and source code if you want to take a look or try it.


https://www.dropbox.com/s/pkrqvs03bnl3e ... v1.cpp.hex
https://www.dropbox.com/s/pkdoj6961rmxu ... %20Fan.zip

[EddB]

If you are working off printrbot wiring for the heatbed (heatbed plugs) on the printrboard, be sure to check the plug wiring with a voltage meter. PB plug wire are red and black. Usually red=positive and black=negative. Not in this case, so don't trust the wire color codes. Check them yourself. The 2 pins closest to the corner are negative. The 2 pins facing the center of the board (or hot end plug) is positive.
The two inner wire (positive) are always on. The mosfets/software controls the 2 wires closest to the corner (negative) . .
Ed

[AmazingSpanoMan]