Make your own simple air-powered engine from scratch

Using basic materials, you too can make this little air-powered engine.
Christopher McFadden

If the video player is not working, you can watch the video from this alternative link.

If you want a basic demonstration engine, but don't want to deal with complex models, then this little build is probably everything you've been looking for. Follow this guide to find out how to build your own.

diy air engine complete
Source: Interesting Engineering

As you can imagine, you'll need some tools and materials before you get started.

Materials and gear needed

  • Plastic drinking straws
  • Cardboard
  • Metal jar lid
  • Old coat hanger
  • Plastic bottle caps
  • Balloon
  • Old business cards or credit card-sized plastic cards
  • Popsicle sticks
  • Surgical tubing
  • Paint
  • Various nuts and bolts
  • A good pair of lungs
  • Power drill
  • Basic tools

With all your gear in hand, it is time to get on with this great little build.

Step 1: Make the bellows

The first step is to take your plastic lids. Drill a hole through the center of the two larger ones. Next, take a pair of balloons (any color will do), and cut off the nipple end of them just below the part where the balloon widens out.

Take the topmost halves of the balloons and push a sharp object through the very top of the balloon to make a hole in each. With that done, take a pair of small bolts, and push them through the holes. 

Then secure them into place using matching nuts on the other side of the balloon.

diy air engine bellows
Source: Interesting Engineering

Stretch the balloon halves over the plastic lids you previously drilled holes through. Ensure the balloons cover the concave side of the lids so that the balloon can expand and contract like a bellows. 

Either glue the balloon into place or secure them, using elastic bands. Trim the excess balloon from the bottom of the lid as needed. 

With that done, take a pair of popsicle sticks and use some hot glue to stick the two bellows together in parallel. 

Step 2: Make the pistons

Next, take your cards and cut out the pieces needed, as shown in the video. Using your hot glue gun once again, glue the pieces of cut plastic card together as needed. 

diy air engine pistons
Source: Interesting Engineering

This will act as a basic piston-like device. Glue this piece to one side of the bellows popsicle stick mounts. Then take some plastic straws and cut some lengths of them to form little pipes from the credit-card assembly to the base of the bellows. 

These will be used to direct intake air into the bellows. Make sure the connection around the straws to the card is air-tight by sealing with hot glue. 

diy air engine pipes
Source: Interesting Engineering

Glue the pipes into place under the bellows as well. With that done, continue to build up the main assembly by gluing more popsicle sticks into place.

Glue some more popsicle sticks into place to make the upstands that will support the crankshaft.  

Step 3: Make the crankshaft

Next, take your old wire coat hanger and cut out some lengths of it using a pair of pliers. With that done, bend the length of wire into the crankshaft shape as needed. 

With that done, cut some more strips of plastic cards, and short lengths of plastic straws. Drill holes in the plastic straw, as shown. Feed the crankshaft through the holes as needed. 

diy air engine pistons
Source: Interesting Engineering

Next, attach the plastic card pieces to either end of the crankshaft too. With that done, glue the plastic card pieces to the popsicle upstands to hold the crankshaft into place above the bellows. 

diy air engine crankshaft attach
Source: Interesting Engineering

With that done, glue the other end of the plastic straws to the nuts attached to the top of the bellows. Test the action by spinning the crankshaft by hand. The bellows should sequentially expand and contract in response. 

Adjust as needed if not. 

Step 4: Finish the engine

Next, cut another length of plastic card long enough to connect the crankshaft to the sliding piston-like assembly of the card you made earlier. 

Glue it into place as needed. 

With that done, take a toothed plastic wheel to act as a kind of fly-wheel, and glue it into place on the other end of the crankshaft. 

diy air engine flywheel
Source: Interesting Engineering

Cover the plastic wheel with a metal lid as shown. With that done, complete the housing for the bellows in any way you like. 

Next, take a length of surgical tubing, or similar, and connect it to the remaining opening on the main air intake to the bellows. 

diy air engine pipe
Source: Interesting Engineering

With that, your air engine is now complete. You can either blow through the pipe to run the engine, or inflate a balloon to do the same!

Have fun. 

If you enjoyed this project, you might enjoy making another simple DIY engine.

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