hot-plug part cooler fan

necrorat

Im in the process of designing a part cooling fan that is attached via magnets to the hot end that is powered via pogo pins. The idea is i can clip it off to give easy visual access to the hotend and nozzle while the first layer is going down and snapped back on once im happy that everything is running smoothly.

My question is are the fan ports on the duet 3 mini going to be able to handle me connecting and disconnecting the fan with the printer under power? or is this a bad idea and i should just drop it?

Phaedrux

If you wanted to get fancy you could have an interlock with a microswitch that would turn off the fan before the power pins are disconnected and then only re-enable the fan again once the switch is depressed again. Handled with conditional gcode.

I'm not sure how tolerant the fan mosfets would be to hot swapping.

infiniteloop

@phaedrux said in hot-plug part cooler fan:

I'm not sure how tolerant the fan mosfets would be to hot swapping.

That should be no problem. But why not swing the whole thing up like a visor? No need to cut the lines, just a small hobby servo to lift the assembly of fan & duct …

necrorat

@phaedrux hmm interesting idea but ideally id like not to have to run more wires to the hotend as its already quite congested. but i do quite like the idea

necrorat

@infiniteloop agin another very cool idea but my hotend is already a thick boy. ill see if i can upload a fusion file of what im working with at the moment.

necrorat

https://a360.co/3PVdewf so this is how it stands at the moment only thing thats missing is the cable chain and 40mm fan on the right side of the hotend.

infiniteloop

@necrorat said in hot-plug part cooler fan:

so this is how it stands at the moment only thing thats missing is the cable chain and 40mm fan on the right side of the hotend.

Thanks for sharing the design. Nice. In this case, it might be getter to "lift" or "retract" the fan assembly upwards. A servo adds 9g to the weight, and you need only two additional lines: 5V and PWM signal. GND should already be there, I suppose.

dc42

@necrorat said in hot-plug part cooler fan:

My question is are the fan ports on the duet 3 mini going to be able to handle me connecting and disconnecting the fan with the printer under power? or is this a bad idea and i should just drop it?

It should be no worse than switching the fan on/off with the mosfet. If you are worried about it, you could connect a resistor of a few ohms in series with one of the wires, for example about 4 to 5 ohms for a 12V fan or 8 to 10 ohms for a 24V fan.

necrorat

@dc42 said in hot-plug part cooler fan:

It should be no worse than switching the fan on/off with the mosfet. If you are worried about it, you could connect a resistor of a few ohms in series with one of the wires, for example about 4 to 5 ohms for a 12V fan or 8 to 10 ohms for a 24V fan.

Perfect, ill go with this for now and if i want to get fancy down the road ill look into using a servo to lift it.