Wanhao i3 PSU Cover 120mm Fan Adapter

by polysquare, published

Wanhao i3 PSU Cover 120mm Fan Adapter by polysquare Oct 29, 2016
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An adapter that lets you mount a 120mm fan to the back of the control box / PSU of Wanhao Duplicator i3 (Monoprice Maker Select V2).This makes the control box quieter and keeps it cool during printing.

  • Version 1.1 (Nov-8-2016, Recommended version)
    • Thickened the tabs that hold the screws that bolt to the printer.
    • Enlarged bolt holes for AC inlet. However, I still recommend using mounting tape instead of bolts here.
    • There are 6 variations
      • SameSide - The hole for the tether is on the same side as the AC inlet
      • OppositeSide - The hole for the tether on the opposite side of the AC inlet
      • BothSides - The hole for the tether is on both sides. There is still only one hole for the AC inlet
      • Invert - The bottom of the adapter is curved instead of the top. The top is flat. For underslung control boxes.
    • If you want your AC inlet to be on the right instead of the left side, mirror the STLs in your slicer.
  • Version 1.0 (Old Version)
    • Initial version, kept here for reference
    • The bolt tabs are a bit weak. V1.1 is recommended.

The adapter mounts to the printer using the screws from the original metal back-plate.

The fan mounts by sliding in from the top, using it's screws as "hooks". You can adjust the tightness of the friction fit by adjusting the these screws. I used this attachment method because the included fan screws were not long enough to screw through the fan into the adapter.

On this adapter, both the tether to the rest of the printer and power cable exit from the left of the control box. There are screw holes to mount the power inlet. However, because the original machine screws did not bite into the printed plastic very well, I used exterior-grade mounting tape between the adapter and the power inlet mounting flanges instead. This turned out to be much more rigid than using two screws.

I installed the adapter using the hex wrenches that came with the printer. However, it was tedious because the wrenches are quite short. It became much easier when I used longer hex drivers.

The fan I used is from a Cooler Master Sleeve Bearing 120mm "Value 4-Pack", but any 120mm should have the same screw pattern.

Fan guard: https://www.thingiverse.com/thing:1595208

Onshape link: https://cad.onshape.com/documents/6458865d07317ea7421b5648/w/8fbe7f67ff219c54f2fa58fa/e/67c2db4929d27824efcfcbc0

Print Settings

Printer Brand:



Monoprice Maker Select v2 (Wanhao Duplicator i3)






0.2 mm layers, 2 shells




The side that the fan attaches to should lay flat on the print bed. Supports are only needed inside the hole for the AC inlet.

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Quick question, if the fan is there to cool the control box, wouldn't it be better to have it blowing in?

How do you separate the power switch from the original back plate? Do you have to unscrew the wires from the power supply? If so, the angle is super awkward

Hi AStorms13,

My power switch/input block was connected to the wires with spade terminals. I could pull the wires off the blades on the input block. Make sure you connect the wires back where they were before or else the metal case of the printer may become electrified.


Awesome design! The only issue I'm having is that my fan won't start. Original test it worked. Plugged it back in after wire management and now it won't turn on. Any ideas or suggestions?

Hi jwetherill,

I can't really recommend anything specific for your case. Perhaps check that the solder joints that connect the fan wires to the fan itself haven't broken off during handling and ensure that power is being applied to the power pins of the fan and not the tachometer signal pin.

Hello, what CAD software did you use for the design?

Hi Zpsmi,

I used Onshape. There is a link to the model on the description page.

Hey, Nice mod. i have a couple of questions

  1. You're pulling air out of the box, right?
    2.Is the fan connected to the cable that used to connect to the small stock fan?
    3.Did you get rid of the original plate at the back of the box?


Hi willybacca,

  1. Yes, I am pulling air out of the box.
  2. It's connected to the stock fan cable.
  3. The original plate is not being used.

Thank you. It's printing right now. :D

Are you blowing air in or sucking it out?

I am blowing air out the back. I believe the original fan sucked air into the box instead.

Thanks a lot for the design. The inverted one works great for my undermounted control box.

I'm a big fan. (☞゚ヮ゚)☞


So what is the original fan size, 40mmx10mm?

Yes, the original fan is a 40mm x 10mm.

("AAA HZHZ 4010MS DC12V 0.12Amax")

can you create a cap for psu cable holes?

I want to print the both sides version in case i want to switch cable sides but i want a cap for one hole

You can make one. :)


Would it be possible to upload a version with the flared part on the bottom? I have my control box slung under the table, so the table would get in the way of the flare.


Hi atruong09,

I'll see if I can get to that tomorrow. I don't think you're the only one looking for such a variant...

I uploaded 3 "Invert" variants with the flared part on the bottom. See if those work for you.

Looks good! I will let you know how it goes when I print it. Thanks for making it!

Can i use it on the old Wanhao I3?

Hi TheDiver,

I don't have a V1 so I can't answer that for sure, but the only reason I can think of why it wouldn't is that the bolt pattern is different. You can compare your printer's bolt pattern to the the measurements in "Bolt Pattern Drawing.pdf" in the Thing Files tab. You can also print out that file at 1:1 scale (actual size) on a 2D printer and compare it that way. Another way is to print out the 1st layer of this thing and see if it fits before committing to printing the whole adapter..

hi i have fitted the box and a gentle typhoon 120mm but my question is i have removed the 80mm on backplate but there is a second 60mm internal i think that still churns out noise can i disconnect the 60mm which i assume is on the psu and the 120mm on the back be enough to cool all internals thanks

Are you sure the back plate uses 80mm?

I thought it was 40mm, and PSU uses 60mm

I am about ready to apply this mod. Did you end up disconnecting the 60mm internal fan? What were your results? Thanks for any information!

Hi, I do not know how much removing the internal fan would affect the PSU's cooling. I have not tried it yet. However, here is another thing (http://www.thingiverse.com/thing:1623141) you can try if you want to explore that route.

Update: I decided to keep the internal PSU's original metal cover and fan because I value the extra fire containment more than the noise reduction. If the PSU fan fails, I will probably replace the fan with a quieter one and/or use a duct to pull air out of the metal PSU cover.

Wanhao PSU vented cover
by Spatz0r

Fire containment of PSU?

You do realize that the PSU is already contained in the metal control box already..
Which should contain any fire..

Unless you remove it, I think that 60mm might still add noise

The internal PSU is quite reasonable. A while ago, I ran it at full load without the cover in open air for awhile. The transistors are heatsunk to the case and they were fine. The diode bridge and transformer did get warm.

I think I'll hold off on running it without a fan until I can get better temperature readings than "doesn't burn finger" though. After all, the PSU designer put a fan of that much airflow in there for a reason. That reason might have been to allow the PSU to operate at higher ambient temperatures or to increase the lifespan of its components.

Hi Madmax2,

Yes, the metal control box should already provide quite a bit of protection.

I've simply decided that, in my own case for now, it's not worth pursuing any more fan noise reduction in the control box or PSU, since the stepper noise already overpowers my PSU fan.

My original motivation for replacing the control box fan was actually because the original 40mm was failing and making very loud squealing and rattling noises. It was much louder than what it was when the printer was new. Throwing a 120mm on it was more fun than just buying another 40mm. I'm just a fan of big fans.

In your pictures I see you are using a Cool Master 0.15 A Fan. Is this 2, 3 or 4 Pins? I would assume 2 pin from what I see inside the box, but just wanted to check.

It's only a two-pin connector inside the box. The Cooler Master fan has a 3-pin connector, but since the 3rd pin is only a tachometer signal, it can be ignored.