Fans
Posted by AVRkire
So with my kit, the seller suggested I tie all my fans into D9 on my Ramps so that when the extruder is going, my fans are going.
I have noticed that my fans seem very slow, and 2 of them just flicker without actually going on.
I am wondering if it would make more sense to just connect all my fans right to my power supply and give them a constant 12 V, so that they are always on and not running through my Ramps board.
Any reason not to do that?
I have noticed that my fans seem very slow, and 2 of them just flicker without actually going on.
I am wondering if it would make more sense to just connect all my fans right to my power supply and give them a constant 12 V, so that they are always on and not running through my Ramps board.
Any reason not to do that?
The reason your fans are not running, or running slowly, is you have them wired in parallel with a 6.8ohm resister that is your heater. Electricity likes to take the path of least resistance, so most of the available power is being used by the heater, leaving very little current for the fans.
That being said, hooking the fans up directly to the power supply will have them running full speed all the time. That's not good. There is such a thing as too much cooling, especially if you use a heated bed. You will have parts curling up at the corners, or popping off the glass due to being cooled at the bed surface.
In my case, my fan is connected to the second extruder output on my ramps. I only have one extruder, and the firmware treats the second output as a cooling fan. This lets the slicing software control the fans speed.
I have my fan mounted on the carriage, in relatively close proximity to the hotend. I set my default fan speed to only 25% duty cycle, and a loop cooling speed of 60%. Bridging is the only time I let it get to 100% for the short burst during the bridge. With this extra control over cooling, I can prevent warping parts at the bed surface, and provide just enough cooling for clean perimeters, and narrow tall parts.
If you want clean and high quality parts, you need to control things based on the size of the object and speed of the extrusion.
Kevin
That being said, hooking the fans up directly to the power supply will have them running full speed all the time. That's not good. There is such a thing as too much cooling, especially if you use a heated bed. You will have parts curling up at the corners, or popping off the glass due to being cooled at the bed surface.
In my case, my fan is connected to the second extruder output on my ramps. I only have one extruder, and the firmware treats the second output as a cooling fan. This lets the slicing software control the fans speed.
I have my fan mounted on the carriage, in relatively close proximity to the hotend. I set my default fan speed to only 25% duty cycle, and a loop cooling speed of 60%. Bridging is the only time I let it get to 100% for the short burst during the bridge. With this extra control over cooling, I can prevent warping parts at the bed surface, and provide just enough cooling for clean perimeters, and narrow tall parts.
If you want clean and high quality parts, you need to control things based on the size of the object and speed of the extrusion.
Kevin
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