Oh boy, I’ve been working on this one for a while.

A year or two ago I set out to build a model windmill that would pump water from the garden pond in my folks’ yard, just for a fun lawn ornament. I went through several different designs for the rotor, the gearbox, and the pump, until finally deciding to just have the windmill operate a bird silhouette to make it look as though the bird were drinking from the pond.

A brief history of the project:

  1. Started experimenting with airfoil blades
  2. Switched to flat blades to better suit the uneven wind conditions near the ground
  3. Designed a gearbox using a 4:1 spur gear reduction and a pitman slide arrangement to drive a pump rod up and down, very much like typical wind pumps
  4. Tried several pumps including a reciprocating piston pump, a diaphragm pump
  5. Delivered original production model
  6. Production model failed due to many alignment and balance problems
  7. Designed new gearbox that better aligned the shafts and used an 11:1 worm drive reduction, achieved far better torque
  8. Decided diaphragm pump was too leaky, designed and built reciprocating pump using large purchased syringe as the piston; pump worked well
  9. Windmill still did not produce enough torque to drive this pump
  10. Designed Archimedes’ screw pump to raise water; screw worked well, but windmill couldn’t reliably transfer power to it
  11. Switched to drinking bird silhouette idea (present day)

I wanted to be able to pump water, but it’s just asking a lot of a system like this (low to the ground, small rotor). I’m still really happy with the windmill itself–particularly the gearbox–and the drinking bird was just a simple load I knew it could handle.

Below are some videos in approximately chronological order. The server isn’t wanting to let me upload photos at the moment, so I’ll try to edit those in later.

Early pump test
Testing the flat-blade rotor with a fan
The new worm drive gearbox (11:1)
Final lawn ornament drinking bird silhouette