What to look for in a cooling fan?

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What to look for in a cooling fan?

Postby flickerfly » Tue Apr 08, 2014 12:47 pm

I've been using junk part cooling fans so far. My current fans are 5V and only seem to run at 100%. I'm thinking I can do better. I'm looking for something with a wide range between slow and fast. Quiet would be nice too. Looking at digikey, I found it easy to narrow down on dba, but I don't know what to look for in how slow the fan will go. Does anyone have some hints for that?

Anything else I should be considering in selecting the perfect fan for cooling my prints?

Here's what I searched out at digikey. I narrowed it down on basically guesses, what little research I found and reason that may be faulty:
Digikey 40mm Fan Search
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Re: What to look for in a cooling fan?

Postby orcinus » Tue Apr 08, 2014 1:07 pm

Anything else I should be considering in selecting the perfect fan for cooling my prints?


Yes. Airflow and bearing type.

If possible, go with MagLev fans.
I believe the particular term "MagLev" is Sunon's trademark, but there should be equivalents by other manufacturers under different names.

5V fans are generally too weak IMHO.

Go with bigger size if you want quieter operation.
50mm fans work well.

Do note that the bigger the fan and the shorter (shallower) its casing, the wider its airflow will be.
Also, there's very little flow in the center of the airflow "cone" - most of it is on the edges, so pointing a fan directly at what you're cooling is fairly counter-productive if you're not directing the flow with a duct of some kind.
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Re: What to look for in a cooling fan?

Postby flickerfly » Tue Apr 08, 2014 1:18 pm

Thanks Orcinus, always appreciate your input. I'd wondered about that center of the cone issue since there is such a big bladeless area, but forgot to ask. :-) In fact, I think you touched on a lot of questions I didn't type out.
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Re: What to look for in a cooling fan?

Postby orcinus » Tue Apr 08, 2014 1:48 pm

Just trying to summarize what i've experienced.
I've got a little graveyard of ditched fans in my closet already :)

FYI, i've tried 40mm Sunons as well and they sucked.
Not enough airflow, too much vibration. You might have more luck with other brands.

Also, i've bought 4 50mm fans and ended up picking two with the least amount of vibration - might be good practice to buy more than you need and cherrypick. Fans aren't terribly pricey anyway.
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Re: What to look for in a cooling fan?

Postby flickerfly » Tue Apr 08, 2014 2:35 pm

Ah, thanks. Have you tested anything with the the range of how slow and fast you can run them? For example, have you had any of the 12V fans run at 25% power? I've seen one run at 50% so far. These 5V Sunons seems to only run at just under 100%, but I guess you know that. :-)
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Re: What to look for in a cooling fan?

Postby orcinus » Tue Apr 08, 2014 4:30 pm

The Sunons i've tried (12V) pretty much can't start at all below 95ish% and won't work below say 85% (you can often start them at 100% and ramp them down to a lower duty cycle than they can normally start from). I keep them always on. I've also had a Scythe branded 50mm fan and a few non-MagLev 40mm Sunons that worked all the way down to about 60%.

You can "extend" the range at which they'll work by adding an electrolytic capacitor in parallel (i.e. across the fan terminals).
100ish uF should do. This doesn't work for all fans, though.
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Re: What to look for in a cooling fan?

Postby flickerfly » Tue Apr 08, 2014 4:35 pm

orcinus wrote:You can "extend" the range at which they'll work by adding an electrolytic capacitor in parallel (i.e. across the fan terminals).
100ish uF should do. This doesn't work for all fans, though.


Oh, that's a great little tip and will give me something to do with a bunch of these little caps I've salvaged.
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