Introduction: Ultimaker 2 – Use 5v Controlled Fan to Also Get a 24v Controlled Fan.

About: I'm blogging about my projects before they make it to Once I've finished a subject on my blog, I'll put it together and post it on Instructables, so you can get a preview on my site.

As people might know, the Ultimaker 2/3 series machines are very sleek, minimalistic looking, with all wires, motors and electronics neatly hidden away.

This is nice from a visual perspective, but it does have some drawbacks in the form of overheating disaster waiting to happen.

This posts covers 2 seperate scenarioes which you can mix as you like:

  • Use the 5v controlled power for the small 25mm fan for the hotend heatsink to also controll a 24v radial fan to cool the electronics.
  • Use the 5v controlled power, as above, to controll a 24v fan for an E3D hotend and the same 24v radial fan as mentioned above.


  1. Intro
  2. Goal
    • Printable Coolboard Duct
    • Controllable fan
    • How it works
  3. Bill of materiale
    1. Prepare the wires
    2. Wire up
  4. Reinstall Controller shield

Step 1: Goal and How It Works


The Ulticontroller is getting rather hot when running, and it is enclosed in a tiny enclosure with no active ventilation. I wanted to rectify this.

Printable Coolboard Duct

My goal was to attach a controllable radial fan to blow into the electronics compartment. I found this nice Ultimaker 2 Coolboard Duct for Control Board Cooling on Youmagine, which you can download for free and print yourself. Seems they have started using my photos, but that's ok :)

There are air ventilation holes in the end of the electronics compartment, which is perfect for our purpose.

Controllable fan

I did not want the fan to run at full speed whenever my printer was turned on though, due to the noise, so something had to be done to make it turn on and off automatically.

I thought about modifying the firmware, but I didn't know the pin numbers on the controllerboard, or even if they were controllable. It would also be rather restrictive for many people, as they run original firmware.

This type of fan is called a radial fan, and is designed to push air through tight spaces.

How it works

I'm going to achieve my goals using a Mosfet control board (example, example), so we are not going to solder seperat small components together, but just wire things together combined with a few wire-connectors (Can do without if you absolutely have to).

Mosfets are the components turning your heaters and fans on and off, so we basically add an extra one to our machine.

I am using this model as I've had best general results with this.

We would normally control these functions using a seperat PIN and some code in firmware. As this option is not available to us, we are going to piggyback on the function allready setup for our 5v 25mm small fan blowing on the Hotend Heatsink. This one turns on and off at 40c, which suits our purpose superbly.

Step 2: Bill of Material and Doing the Wires

Bill Of Material

  • Radial Fan 50mm x 15mm
  • 1x DC control MOS FET switch control panel
  • 2x male and 1x female XH2.54 connector. Buy a box.
  • 2x female dupont connector + pins. You can use a male XH2.54 connector plug if you have to.
  • 8x male dupont pins. Can do without, but highly recommended.
  • Some heatshrink
  • Kapton tape or similar
  • 2x 35-40mm m3 screws if you use the printed Duct.

Prepare the Wires

As you can see here, we are going to create 4x pieces of wires:

  1. Wire from Controller 5v connector to Mosfet control
    1. 5-6cm with male XH2.54 to 2x male dupont pins
  2. Wire from mosfet control to original 25mm fan Connector
    1. 10-11cm with female XH2.54 to 2x male dupont pins
  3. Wire from mosfet DC out to Radial fan connector
    1. 6-7cm with male XH2.54 to 2x male dupont pins
  4. Wire from Controller 24v power pins to Mosfet DC in
    1. 16-17cm with 2x female dupont connectors to 2x male dupont pins

Optional: Instead of #4 you can use the unused Controller FAN connector at the end of the controller.
8-10cm wire with male XH2.54 connector to 2x male dupont pins

Optional: Instead of the first 2 seperate wires you can create a combined Y wire, meaning 1 male XH2.54 connector to 1) 2x male dupont pins and 2) 1x male XH2.54 connector

Wire up

  • Number 1 is the 5v connector on the Controller. This wire goes to the control in port on the Mosfet control board.
  • Number 2 is the 24v output pin on the controller. Goes to DC in on the Mosfet Control board.

Here you can see the short wire from Mosfet Control board Control in to the original connector up to the 25mm fan. This just pass on the 5v.

I have an E3D on one of mine, and use a 24v fan for its’ heatsink. Just connect this short wire to the Mosfet Control board DC OUT insteaad, same as for the Radial fan.

I’ve used the printed parts from the E3D Ultimaker 2, 2+ Upgrade Conversion Kit for this E3D carriage.

Here you can see the wire from Mosfet Control board DC OUT to the Radial fan. It also shows the place we are going to stash the control board, but we need to prepare it a bit first.

Before putting the Mosfet Controller board into it’s hiding place, we must make sure there is no shorts going to happen. As you can see, I’ve simply wrapped Kapton tape around mine.

It’s not going to generate a lot of heat, so don’t worry about that.

Before wrapping Kapton around it, you should make sure the pins on the backside of the board doesn’t poke through. Use a small wirecutter to shorten them as much as you can.

Step 3: Reinstall Controller Shield

I’ve done this a lot, and thought I’d make a seperate section for it to make it easier to get it right the first time.

  1. First slide it gently down like photo 1. Make sure all cables are inside.
  2. When you have caught all wires inside it, you should tilt it like on photo 2 and make sure the “pin” next to the motor is correctly inserted into the hole in the frame.
  3. Now tilt the shield back and fix it in place.