Introduction: Multi-Purpose Doughnut Fan

Tired of soldering fumes getting in your line of sight when soldering? Tired of not being able to test your new airplane design when you need to? Then try out building this amazing device!

This project is a multi-purpose portable blower that can be a solder fumes filter, a magnetically attachable air mixer, a personal cooler, and a magnetically attachable fan for a wind tunnel if you so desire. (OPTIONAL: micro wind tunnel Instructable not ready)


8 mm coreless DC motor

Ladybird Propeller Prop

3D printer with at least a 0.4 mm nozzle and filament

2- single pin male 2.54 mm pin crimp connector

2- case to house 2 crimp connectors side by side

2- single pin female 2.54 mm pin crimp connector

22 AWG gauge wire, black and red (5 inches at most (for mistakes))

8- 4 mm thick, 6 mm diameter magnets (mine came from some old magnetix pieces

Electrical tape or heat shrink (around 1 in of heat shrink)

Hot glue gun and hot glue (preferably a Hi temp one)

Electric hand drill

1/4 in (6 mm) sized drill bit (or the diameter of your different magnets)

Crimps for the 2.54 pin crimp connectors

Wire strippers for 22 AWG gauge wire

Calipers (for precise measuring (if designing your own))

Multi-meter (to check for shorts and continuity)

Small needle-nose pliers (to remove supports)

Small flush cuts

Wire cutters

Battery (AAA, AA, 1s Li-Po) (wired up properly)

Step 1: Gathering the 3D Printed Parts

For a full tutorial on designing the Doughnut fan, please refer to this Instructable. (SORRY! Instructable is not made yet.)

If you want fully ready designs, here they are!

Print out the pieces. The standard ring frame should need no supports, as having them is a pain to take them out of the airflow holes is very hard.

The Standard Base will need supports, but if possible, have no supports in the magnet holes.

The Splitted Base gives more ease of printing but has not been tested in the build process.

Using the magnet sized drill bit (mine was 1/4 in), widen the holes for the magnets to fit snugly in. Do not drill to far or you will destroy other parts of the printed part.

Note: Drill the holes to the size of your magnets, or edit the 3D printed file to accommodate the different magnets

Step 2: Installing the Motor Into the Frame

Installing the motor is relatively simple.

Strip the ends of the motors wires so they can be crimped to the 2.54 mm female connectors. If the wires are too small (smaller than 28 gauge), solder them to the 22 gauge wire (provided that both ends are stripped on both sides at least 5 mm) and crimp the connectors onto the bigger wire. Heat shrink or cover the connections with electrical tape to stop accidental shorts.

With the wires wrapping from the bottom of the motor to the side, put the motor in so that the wires that come to the side of the motor become routed into the cavity by the motor mount hole (see pictures). Secure the motor on the fame with hot glue or any preferred glue.

Insert the female connector into the rectangle cavity in the side of the frame. Secure it with hot glue or any preferred glue.

Insert the ladybird propeller onto the motor or design your own quieter version of a propeller that suits you.

Step 3: Installing Magnets

To find the polarity of the magnets, I used a compass. When the compass pointed "north" to a magnet, The magnet is marked to show the pole being south (or pole B); and if the compass points "south" to the magnet, that magnets pole is marked as the north pole. Mark all magnets' of south and north poles.

On the fan frame, the north sides of the magnets face out when put in. On the stand, the south pole of the magnets faces out to connect well to the frame. This uniform polarity of the frame and stand allows for the power plug of the frame to face in any way so the cord can be easily routed anywhere.

If you haven't done so already, drill the holes wider with the magnet size drill bit. insert the magnets with the proper polarity. If the magnets fall out too easily, secure them with super glue. Test magnetic connections to feel how loose they might be and secure them as needed. The part should give a snug fit.

Step 4: Making the Battery a Plug.

To do this, you need the 2 pin male connections and the battery of your choice. (works fine with AAA, AA, 1s Lipo (mine has a protection circuit), etc (nothing much over 5v though).

Strip the ends of the Li-Po about 5 mm back. crimp the connectors on the the wires, and install the terminals into the plastic case (see pictures)

Test the battery on the fan. The fan should spin up and make a sound. Lots of sound. Unless you have a quieter propeller than I do.

You have finished the basic doughnut fan

Step 5: Optional: Making a Fan Control Circuit, Supplies

You will need the optional supplies:

The physical circuit board from the Gerber file

( )

Mofset Transistor (TO-220F-3_L10.2-W4.7-P2.54-L)(easyEDA)

Small blue variable resistor (RES-ADJ-TH_3P-L6.8-W4.6-P2.50-TL-BS-3266X)(easyEDA)

1x2 male header (optional, if want the board to come off of the fan)


Soldering iron

You need to solder on the parts correctly for the circuit to work

Step 6: Optional: Circuit Schematic and Starter Code

The purpose of the PCB is to control the fan's speed. If the variable resistor is turned, it will change the speed of the fan, depending on what way the resistor was turned.

The additional files are files to use an Arduino UNO and a L9110S 2 channel motor driver to control the fan.

The choice of control is yours!

Step 7: List of Improvements and a Gallery of Doughnut Greatness.

Some things to take the project further:

1. Make a circuit to control the fan well to fit on a 7 by 5 cm protoboard (base of trapezoid)

2. Make the fan less loud

3. Make a cool propeller!

4. Insert a Neopixel ring in it for light ascetics!

5. Put several of them in some of your own designs! Like 2 of them on a long pole that spins like a helicopter!

3D Printed Contest

Participated in the
3D Printed Contest