Replacement for hotend fan
The hotend fan failed within two days of assembly. Due to technical reasons I get can't get a replacement from prusa anytime soon so I'm looking to buy locally in the meantime. Problem is that I barely found one that's 40*40 and 5v. What I did find is 20mm thick with 4 wires (one for control and one for some kind of feedback) . Will it do?
Best Answer by BogdanH:
Yes, if possible, get fan from Prusa -if nothing else, just to avoid potential hassle.
But if you look on free market, then keep in mind:
1. It should be 5V fan. Even 7V fan can be run at 5V, you probably won't know what rpm (air flow) you'll have if running it at 5V. I don't know all speed variations used in Mini... but it can also happen you would have fan "start-spin" problem in case when fan should start at low rpm -in this case 7V won't start spinning at all (at least that's the case for some fans).
2. You can pick 4-wires (PWM) fan if that's the only option you have (in this case PWM wire just isn't used). *See below
3. Original fan has 8000rpm at 5V (at least according to official documentation). As airflow also depends on fan blades design, you can use some that has a bit lower rpm -but I wouldn't go below 6000rpm.
*-Prusa documentation is confusing in this regard... Here black wire is signed as PWM, but 3-wire fans don't have PWM capability (that's why 4-wire fans exist). Here however (also from Prusa), wires are described correctly (page 6).
I think 20mm thick fan can't be used, because SuperPINDA would be mounted too far from hotend. That is, during auto bed leveling, it would go off the print bed.
[Mini+] [MK3S+BEAR]
thanks
thanks. that's what I was worried about actually.
what about 7v
I also found 40X40X10 fan with variable speed but for 7v? any chance it would work?
RE: Fans
I would buy the fans from Prusa, but if you must, Noctua make the fan you are looking for. Do a google search for “noctua 5v 40mm fan”. You will find it.
LDO also make a compatible fan.
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Chuck H
3D Printer Review Blog
Yes, if possible, get fan from Prusa -if nothing else, just to avoid potential hassle.
But if you look on free market, then keep in mind:
1. It should be 5V fan. Even 7V fan can be run at 5V, you probably won't know what rpm (air flow) you'll have if running it at 5V. I don't know all speed variations used in Mini... but it can also happen you would have fan "start-spin" problem in case when fan should start at low rpm -in this case 7V won't start spinning at all (at least that's the case for some fans).
2. You can pick 4-wires (PWM) fan if that's the only option you have (in this case PWM wire just isn't used). *See below
3. Original fan has 8000rpm at 5V (at least according to official documentation). As airflow also depends on fan blades design, you can use some that has a bit lower rpm -but I wouldn't go below 6000rpm.
*-Prusa documentation is confusing in this regard... Here black wire is signed as PWM, but 3-wire fans don't have PWM capability (that's why 4-wire fans exist). Here however (also from Prusa), wires are described correctly (page 6).
[Mini+] [MK3S+BEAR]