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How to Build a Centrifugal Fan

A centrifugal fan moves gases. such as air. around an environment. Also known as blowers, tornado fans or squirrel-cage fans, these fans generally rotate around a driveshaft. The gas being driven is drawn in through the side of the fan's wheel and is turned at a right angle before being expelled. Because of the centrifugal forces involved with turning the wheel, the gas is moving with considerably more force when it leaves the machine. For high school students looking to explore these forces in a science fair project, it is fairly easy to build a centrifugal fan and use it for testing its effects.

Things You'll Need

Drill with 5/16-inch bit
Round fan plate
Fan blades
Collar
Welding torch
Welding goggles
2 fan housing plates
Housing side strip
Threaded inlet
8 bolts, 5/16-inch diameter by 5/8-inch long
Threaded rod, 5/16 in diameter

Instructions

- 1
  Use the drill to make a 5/16-inch hole in the middle of the fan plate. Slide the bolt down through the collar for the shaft and the plate. Use a nut on the other end to secure it.
- 2
  Weld the collar down to the plate, leaving a gap for the set screw for later. Loosen the nut and take it and the bolt out.
- 3
  Add a fan blade to each slot. The outside edge of each blade should rest evenly with the edge of the plate. Weld the blades into place by joining them to the plate at two or three different spots. However many welds you use, spread them out evenly.
- 4
  Put four bolts into the housing plate for the bottom. Tighten with nuts and then weld the bolt heads so that they won't move. Slide the side strip into the tabs that you will find on the housing plate. Weld each tab into place before you insert the next one. When you're done, turn the plate over and weld the tabs into place where they stick through the slots as well.
- 5
  Repeat Step 4 for the top plate, using the same side strip attached to the bottom housing. Slide the nipple onto the outlet hole and weld in place, all the way around the nipple. Place the housing onto the motor and slide the fan inside.

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