Fan Control

General discussion of 3D printers

Fan Control

Postby tmccafferty » Tue May 21, 2013 1:58 pm

I would appreciate folk's thoughts on fan control on a multi-extruder printer.

I am building a large format printer (550mm cube envelope) and it will have two extruders. I am using a Ramps 1.4 board with Marlin. Power outputs D8, D9, and D10 get used up on 2 extruder heaters and one bed heater. I will be using 1.75mm J-Heads with seemecnc EZStruders. I have seen some folks post that you don't need a fan on the J-Head even with PLA. I have a fan on my ordbot J-Head and have never had any jamming problems. Actually, I have three fans on my ordbot (j-head, material, and motor shaft/gear). I am hoping that with the EZStruder and J-head, I don't need the fan on the motor shaft/gear. After my early experiences with QU_BD extruders, I want to be conservative here....

It's easy enough to grab unused outputs and run them through MOSFETs or SSRs but the software integration is another story.

Here is what I need: (assuming no fans needed on motor shaft/gear)

1) Extruder 1 hot end fan - ON anytime extruder is heated
2) Extruder 1 material fan - proportionally controlled based on material printing and slicer strategy
3) Extruder 2 hot end fan - ON anytime extruder is heated
4) Extruder 2 material fan - proportionally controlled based on material printing and slicer strategy

Cases 1 and 3 could be handled by placing M42 commands in the start/stop gcode. This isn't very elegant, but could work as long as you don't preheat too long.
I guess cases 2 and 4 could also be handled with M42 as I currently only have the material fan on at 100% when printing PLA. There is a Marlin request #409 out there for this functionality, but doesn't appear to be happening.

I think fan control is pretty important on the printers and would like it to "take care of itself".

Any clever ideas on this?
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Re: Fan Control

Postby cozmicray » Tue May 21, 2013 4:46 pm

Check out these

Cooling Fan MOSFET Driver

RRD-FAN-EXTENDER for RAMPS1.4 ... ender.html

I would attach extruder cooler (1 and 3) directly to 12V so they are ON all the time.

but that may cause plug up in long j-head neck?

I could never understand heating up a J-head and then cooling it with a fan?
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