Introduction: Windmills and Gear Ratios

This guide extends beyond the simple windmill from the “Simple MacGyver windmill that lifts weight” Instructable to explore the mechanisms that affect the amount of weight your windmill can lift and how quickly the weight will be lifted.

Step 1: Materials

  • simple windmill (see “Simple MacGyver windmill that lifts weight” Instructable for details)
  • spool-like objects of different sizes (ie hole-less pool noodle piece)
    • alternately, you can use the “Custom Spool,” which can be found athttp://store.kidwind.org/catalog/customspool

  • box cutter/utility knife
  • tape
  • box fan

Step 2: Begin With the Simple Windmill

For full guide for how to make this, see: “Simple MacGyver windmill that lifts weight” Instructable.

Step 3: Exchange the Spool at the End for a Bigger Size

The radius of the spool affects the ease and speed of the weightlifting. Try making a larger one, such as out of the pool noodle piece. Score two lines with the utility knife about ⅛ from each edge that go all around the circumference of the noodle.

Wrap the space between the two lines tightly with tape, making the middle section slightly indented from the edges. This creates a spool-like shape that will keep the string from falling out.

Exchange the spool for the pool noodle piece. You may want to glue or tape the pool noodle to the dowel (if it is not securely attached, the dowel will spin without the pool noodle piece and your windmill won’t be able to move any weight). Take the string that is connected to the spool, disconnect it and attach it securely onto the indented part of the pool noodle, in such a way that the string will be able to wrap around the noodle.

How does the bigger size affect how much weight can be lifted? How does it affect how quickly the cup lifts?

Step 4: Exchange the Spool at the End for a Smaller Size

Try your windmill without any spool, letting the string just wrap around the dowel.

How does the smaller radius (as opposed to the spool) affect how much weight can be lifted? How does it affect how quickly the cup lifts?

Step 5: Exchange the Spool for “Custom Spool”

Alternately, you can use a piece called the “Custom Spool” instead of finding and making spool-like objects with different-sized radii. The Custom Spool gives three radius options in one piece, allowing experimentation without having to keep changing the end of the windmill. The Custom Spool can be found here: http://store.kidwind.org/catalog/customspool

If using the Custom Spool, put in place of the regular spool. You may want to glue or tape it to the dowel (if it is not securely attached, the dowel will spin without the spool and your windmill won’t be able to move any weight).

Remove the string from the regular spool. Attach the string securely to whichever size you would like to start with. When you want to experiment with different sizes, just move the tape to another level.

Test your windmill in front of a box fan with each of the levels of the Custom Spool. On which level can your windmill lift the most weight? On which level does it lift weight the fastest?

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