Turbo Desk Fan - a free 3D model from Shapekit

A real, working desk fan that looks like the turbo from a car engine. The impeller pulls air in through the front and the snail-shaped housing blows it out of the outlet. A knob in the base sets the speed.

Parts (each STL is already placed the right way up for printing)
- turbo-fan-housing.stl: The turbo 'snail' with the air inlet at the front and the outlet on top. Print: Standing on its mounting flange, with tree supports.
- turbo-fan-impeller.stl: The compressor wheel that spins inside the housing. A 5 mm flange coupling screws onto its back with 4 × M3 × 10. Print: Back plate on the bed, no supports. Looks best in a bright colour.
- turbo-fan-motor-holder.stl: Closes the back of the housing. The motor's front face rests on a web inside the sleeve and is screwed to it with 2 × M4 × 8; slots let the motor breathe and give access to the coupling's set screw. Print: Flat side down, no supports: the web inside the sleeve prints as a bridge. Then cut the thin skin out of its three holes with a knife. PETG if you have it: the motor gets warm.
- turbo-fan-base.stl: The foot, open underneath. The speed controller hangs inside on its knob (Ø7.5 mm hole in the front); the back has a Ø8 mm hole for the DC power jack and a Ø7 mm hole for the motor wires. Print: Upside down (top face on the bed), with supports.

Also needed (not printed)
- A 775 DC motor, 12 V: body Ø42 × 66.7 mm, Ø5 mm shaft at least 15 mm long (17 mm is usual), two M4 holes 29 mm apart in the front face. A ball-bearing one is quieter.
- A rigid flange coupling for a 5 mm shaft: flange Ø22 mm with 4 × Ø3 mm holes on a Ø16 mm circle, Ø10 mm boss, 12 mm long, M3 set screw. Plus 4 × M3 × 10 pan-head screws.
- 2 × M4 × 8 pan-head screws to fix the motor in the holder.
- A 12–24 V PWM DC motor speed controller with a knob, rated 5 A or more (10 A is safer for a 775). Its potentiometer needs an M7 bushing with a nut (6 mm shaft); the board can be up to about 80 × 60 × 35 mm.
- A 12 V power adapter of at least 5 A with a 5.5 × 2.1 mm plug, and a DC-022B panel jack (5.5 × 2.1 mm, for an 8 mm hole).
- 8 × M6 × 20 bolts, 16 M6 washers and 8 M6 nuts for the Ø8 mm holes: 4 for the housing on the base, 4 for the motor holder.
- About 50 cm of two-core wire, 0.5 mm² (20 AWG), and a 1.5 mm hex key or hex screwdriver.

Print settings: 0.4 mm nozzle, 0.20 mm layer height, 3 walls, 15% gyroid infill, PLA or PETG material.

Assembly
1. Print the parts: Print the housing and the base with supports, the impeller and motor holder without. Remove the supports from the inside of the housing carefully, so the impeller can turn freely. Cut the thin skin out of the three holes in the motor holder's web.
2. Build the base: Put the controller's knob through the Ø7.5 mm hole in the front and tighten its nut; the board hangs inside. Fit the DC jack in the Ø8 mm hole at the back and wire it to the controller's power input.
3. Mount the motor: Solder the wires to the motor. Slide it into the holder from the back until its front face rests on the web, the bearing boss in the centre hole, and screw it on with 2 × M4 × 8 from the plate side.
4. Fit the impeller: Screw the flange coupling to the back of the impeller with 4 × M3 × 10, boss pointing away from the impeller. Push it onto the shaft until the impeller is 2 mm from the holder's plate (a 2 mm hex key makes a good spacer), turn the set screw to the slot in the top of the sleeve and tighten it with a 1.5 mm hex key.
5. Close the housing: Push 4 × M6 × 20 bolts through the back flange of the housing from the inside (a strip of tape holds them), slide the holder with the motor and impeller over them and fix it with washers and nuts. Turn the impeller through the inlet: it should run free, with about 3 mm to spare at the inlet.
6. Put it together: Bolt the housing onto the base with 4 × M6 × 20, washers and nuts from below. Lead the motor wires into the hole at the back of the base and connect them to the controller's motor output.
7. Switch it on: Start at the lowest speed and turn it up slowly. If the air comes out of the inlet instead of the outlet, swap the two motor wires.

Safety: The fan spins fast. Only run it fully assembled, keep fingers out of the inlet and start at the lowest speed. Use a plug-in power adapter unless you know how to work safely with mains power.

License: Creative Commons Attribution-NonCommercial 4.0 (CC BY-NC 4.0)
https://creativecommons.org/licenses/by-nc/4.0/
Print it, remix it and share it, as long as you credit Shapekit and don't sell the files or the prints.
