Silent 24V fan?

So I just got a relatively cheap 24V 800W chinese power supply. It seems to work fine but the fan is unbearably loud. Since all my other fans are extra quiet this one really stands out.

It is a 24V 60x60x25mm chinese fan but seems quite powerful. I have been thinking of the following solutions:

1. Use a silent 12V fan with a simple voltage divider or a cheap LM2596
2. Use a larger fan with lower RPM which is ultimately going to be quieter
3. Use a silent 24V fan

Option 1 seems to be the easiest and cheapest one but the air flow may be a problem (there is no technical spec for the current fan but it blows like hell so I guess about 30 m^3/h)
Option 2 is the least preferable one because this is impossible to do while keeping the form factor
Option 3 could be the winner if someone suggests a powerful and quiet fan...

Thanks a lot for your help!

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

Why are you using an 800W power supply? Based on the description of your machine in your signature, it appears to me that a fanless 300W PSU would be more than adequate.

btw I hope your RAMPS board is rated for 24V (most have 16V capacitors), and you have a separate 5V regulator to provide the 5V supply. 24V systems normally use better electronics than Arduino/RAMPS.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Yes, you have a point there.

However, my signature shows the current state of the machine. I am going to upgrade the heated bed with a much bigger one (400W just for the bed heater). Chinese PSUs have not more than 80% efficiency and the nominal power is strictly theoretical. So this is why I went for a larger PSU with some power to spare in order to avoid having a smaller PSU run at nearly full power. I furthermore plan to add a second extruder so I wanted a PSU with some power reserve.

I have a separate LM2596 which takes care of the Arduino 5V power supply. At first (stage 1) I am going to run the RAMPs at 12V with a separate 12V regulator and afterwards (stage 2) I am probably going to opt for better electronics.

So in any case I am going to stick to the loud PSU which leads us to the question in the first post

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

For a 400W bed heater, I would use a mains voltage heater (as I do for my 350W delta printer bed heater) - although this does involve additional safety considerations, especially if the bed is moving.

Returning to your original question, my preference would be to use a larger, slower 24V fan. But this is only viable if your PSU can accommodate it.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Well it is a mendel-style moving bed, so properly grounding it could be tricky. Nothing impossible but I didn't want a mains powered bed. Instead I am going to power it with the 24V PSU using a signal pin from the RAMPs and switching it through a MOSFET.

Using a larger 24V fan would mean having to remove the top cover of the PSU which ultimately means that it would not fit the slot where I wanted to mount it... So this is why I am not very keen on taking Option 2...

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

In that case I suggest you measure the dimensions of the existing fan, then search the web sites of the electronic component distributors in your area for 24V fans with the same dimensions but a low noise level. The airflow will probably be lower than the current fan, but if you will be running the PSU at well below its maximum rating then this may not matter.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Look for Noctua fans, they are very well made and some of the quietest fans available. They should have one to fit your specs. You do need to watch whether you need a 2 pin or 3 pin variety though.

Noctua doesn't really offer a 24V 60mm fan. In addition to that I didn't quite find a plethora of silent 24V fans (<20 d which is why I thought of Option 1 - for example this one has a decent airflow to noise ratio which I guess is comparable to a less powerful 24V fan...

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

I found this [www.ecrater.co.uk] which is the right physical size and available in 24v version. The blurb states that it is ultra quiet however the quoted DBA figure doesn't reflect that. Might be worth dropping them an email to see if there is a misprint on the spec?

Option 4: use a resistor to pull it down to for example 14 volts ?
For sure you need a well calculated resistor and put it somewhere infront of the fan to also cool it down.

Chri

Edited 1 time(s). Last edit at 08/18/2016 02:02PM by Chri.

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