Noctua 5v 40mm fan only running at max power

bartolomeus

Today I received two of these: https://noctua.at/en/products/fan/nf-a4x20-5v
and connected them to the Duet. They work, however they only run between 97-100% power. Anything lower and they stall. Did I miss something or was this to be expected?

Phaedrux

How do you have them connected?

bartolomeus

@phaedrux With only 5v and ground connected.

bartolomeus

This post is deleted!

Phaedrux

You said you're running two of them, are they connected in series, or in parallel?

bartolomeus

@phaedrux None of both. One is layer fan, other is hotend fan.

Phaedrux

You can try varying the PWM frequency or adding a blip time of full speed. some fans won't start at low speeds without a true PWM signal.

Those fans are very quiet. Is there an issue with running them at 100% power? For the layer fan when printing PLA that probably wouldn't be an issue since it's not the most powerful fan to begin with.

For a good controllable 5v blower Sunon has some good options.

bartolomeus

@phaedrux I agree it probably won't be a big problem for the layer fan. It really doesn't move that much air. I needed my printer to make less noise as its in the living room and this seemed like a good option. However I really doubt it moves enough air..... I'll have a look at the sunons.

Phaedrux

I use the 12v version of that fan for my hotend fan and it seems to perform alright.

bartolomeus

@phaedrux you mean you have the sunon or the noctua for the hotend?

Phaedrux

@bartolomeus Sorry, I meant to say, I use the 12v version of the Noctua 40mm you are using on my Titan Aero and it seems to work fine. I use a 12v Sunon blower fan for the part cooling, but it's not exactly quiet above 50%. However it does have a very wide usable PWM range, which makes it flexible. Sunon also makes 5v versions of blowers which are quite good.

bartolomeus

@phaedrux thanks for the tips. I am not worried about the hotend fan. I'll see how it performs as layer fan. If it doesn't do well, I'll look for something else.

dc42

Try varying the PWM frequency as @Phaedrux suggested. In particular, try reducing it.

bartolomeus

@dc42 Thanks. It's on tomorrow's to-do list, including the blip time.

mrehorstdmd

Since the subject is quiet fans here, I recently bought a hot-end via Ali-express and it came with a 24V cooling fan. That fan is about as quiet as the Noctua fan on the Prusa i3 at the makerspace. I know the Noctua fans aren't available as 24V units, so if you're looking for a dead quiet 24V fan you can get them here

I haven't had the unit in my printer for long, so I can't say anything about reliability.

Unlike most of the inexpensive stuff from China, these things have actual data sheets with real specs.

bartolomeus

@dc42 said in Noctua 5v 40mm fan only running at max power:

Try varying the PWM frequency as @Phaedrux suggested. In particular, try reducing it.

Ok, so did that:
at 25,100, 1.000hz and there was no difference
tried 25.000 as that is suggested for PWM fans (which this one is not), and now it starts at about 35% power.

Should I leave it at this, or look further?

dc42

Try lower, e.g. 100. High frequencies such as 25000 should only be used with 4-wire fans.

bartolomeus

I did try lower. 25, 100, 1000, with no effect