Hello,
I wonder if its possible to add an extra cooling fan that starts after print to cool the heatbed. I have glass and use PVA. I works very good but it takes long time to cool down to under 35 degrees (then it´s easy to remove). Is there any pins that I can use on the board for that?
Thank you in advance.
/Olov
Do you have the LCD controller mounted?
If so almost any pins are already in use.
What you can do for example is use one of the endstop microswitches to trigger a bed cooling fan.
That would turn the fan on, when the printer is homed on that axis. (x axis home for example)
The you simply have to home the axis to switch the cooling fan on.
Thank you for your answer. I don’t have LCD but your solution seems good. Is it possible to connect the fan directly to the switch. Is it 15 volt there? Or should I use an relay?
No, the switch is logic level (5V).
But the endstop switches are bipolar.
The leftmost pin is common, the middle one normally open, and the leftmost normally closed if oriented like in the picture below.
So, what you can do is:
- connect gnd to the leftmost pin.
- connect the negative wire of the fan to the middle pin
- connect the endstop signal to leftmost pin.
The positive wire of the fan goes to +15V.
That way the fan is switched on when the endstop switch is triggered, by closing the connection between mid and left pins.
While maintaining endstop operation by opening the connection between left and right pins.
Just take care when wiring up and TRIPLE check, so you don’t accidentially connect +15v to the endstop signal wire,
as that would burn your atmega chip.
The wiring should be able to take the load of the fan, so you would only have to route 1 additional +15v line to the fan.
left pin -> ground
mid pin -> normally open (connect negative of the fan/ fan ground)
right pin -> normally closed (endstop signal wire/endstop +)
Thank you very much.
I will try when I get home!
[quote=“olovfr”]Thank you very much.
I will try when I get home![/quote]
Please let me know the results and pobably post some pictures.
I thought about this mod ahead of time, but didn’t realise it yet.
Too much parts watiting to pint … 
cheers,
Christian
Hello
It worked very well!
I have connected a 120mm Noctua fan and set the bed to go forward and to endstop at the end of every print. I plan to put the fan at the front side so that it dosn´t cool down the print at start time. I will post pictures when I have printed fan holders and properly installed the fan.
¨
Thank you very much!
Cool!
Cant await to see your results!
cheers,
Christian
This is the fan with holder.
Im very happy with this!
dropbox.com/sc/8hj7pex3klqb … t4q-TE1rha
Thank you again! It´s people like you with the knowledge and helpfulness that makes it possible for us other to have fun with this kind of printer.
Looks quite nice!
I think i have a next project …
