Whirligig Experiment

I’ve wanted to make a whirligig for a while, so today was good as any to give it a try.  The heart of any whirligig is the propeller, and since I have no idea how to make one, a lot of guessing will be in order.  All of the assembly was done by David, I only did the propeller part.

 

 

 

So here are a few thoughts before tackling the propeller part:

  • It should be a light as possible
  • The angle of the blades (rake?) should not be steep
  • The propeller blades should be fairly long
  • And finally, the prop has to be well balanced

For the sake of experimenting, I will use pine for the construction.  Final versions will use a hardwood, perhaps birch.  Overall length was arbitrarily determined to be 8″, and I used a scrap piece that measured 1″ x 3/4″.  With the material cut, was time to start shaping.  To make the process easier I cut away the waste using a back saw.  A rasp bit mounted in the drill press made short work of the final shaping.

Whirligig Propeller - Pine Whirligig Propeller - Removing Excess Material Whirligig Propeller - Shaping

The next step was to drill a centered hole and insert a small metal tube that was slightly larger than a 1/4-20 bolt.  This will allow for smoother action and will protect the wood from wear.  The fuselage is the same pine material used for the propeller, and the vertical stabilizer is 1/4″ plywood.

Now that all the pieces are assembled, the center of gravity must be determined.  Just use something round, and move the object back and forth until is stays balanced.  Make a mark on the side, and drill using a drill press.

Since this is mounted on a steel post, I put a bit of metal in the hole to keep the shaft from working through the pine.  I also put a dab of grease in the hole.

Whirligig Finished Whirligig Finished

And experiment, and we learned some things.  First, the prop can be much longer and thinner.  The rake needs to be less severe and I would like to find a better bearing method for smoother spinning.

 

Here’s a gallery of the pics:

Comments please!