Kinetic Windmill Sculpture
Martin Munson constructs a kinetic windmill sculpture from a bicycle.
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Materials and Tools:
wire feed welder
angle head grinders
metal cutting band saw
propane fired forge
hammer and anvils
sheet metal shear and brake
24-gauge hot rolled steel sheet metal
stainless steel sheet metal: recycled restaurant counters
24-gauge recycled scrap copper
1/2" steel pipe
5/16 diameter steel rod
1/2" diameter x 1" bolt with nut
welding safety glasses
flat black spray paint
red spray paint
*Muriatic acid is a hazardous chemical.
1. Disassemble a three-piece crank assembly bicycle (figure A).
- Cut cables, chain and remove the left pedal.
- Save the chain ring and crank. This will become the propeller hub. Save the round tapered lock pin with the flat side washer and nut.
- Cut and remove the pedal from the sprocket 1-inch above the lock pin.
2. Cut the bike frame:
- Crank assembly: (This is the part of the bike with the pedals and chain.)
- Cut large pipes 1 inch up from the lugs and cut small pipes 1/2 inch from the lug (figure B).
- Headset Assembly:
- Remove "wheel forks" from the sides of the steering shaft leaving the shaft full length.
- Bike Frame:
- Cut the bike frame six inches from the headset.
- Stamp the frame ends flat inline with the vertical axis.
3. Grind the edges of the now flattened frame tubes to receive rudder sheet metal. Drill holes in the center of the flattened tabs for a 3/16-inch pop rivet.
4. Disassemble the crank assembly and the steering column.
5. Place all kinetic components into a small tub (with a lid) of solvent and soak. Clean grease and rust off the bearings and threaded parts, etc. with a wire brush. Note: Wear rubber gloves, respirator and goggles when using solvents. Adequate ventilation is required.
6. De-bur and grind all edges smooth.
7. Cut to dimension all metal parts:
- One 3/8" x 1" flat bar 5-1/2" long to hold "motor" in line with windmill frame
- One 1/2" x 1" C-channel to mount flat bar at right angle to windmill frame
- Two 1-inch copper plumbing end caps
- Two 5/16-inch diameter steel rod to 32-inch lengths to become rudder spins.
- Four 22-gauge copper tabs 1-1/4" x 3-1/4" to hold rudder into frame.
- One 20" x 30", 24-gauge mild steel sheet metal to become moon face.
- Two 1" x 1/8" x 3" flat stock, drill two 1/4 inch diameter holes 1/2 inch from ends on center
- One 1/2" x 5' black steel pipe
- One 1/2-inch course thread nut for top of mount pole
- Three 22-gauge stainless steel 13" x 6" cut to shape of propeller blades
- One 1/4-inch diameter steel rod 13 inches long to become nosecone corkscrew
8. Grind all edges and prep for welding.
Forge and Hammer
9. Wear eye protection and gloves. Holding the steel in tongs or pliers, heat it to the point of malleability in a gas-fired furnace (or use an oxy-acetylene torch). Forge the corkscrew nose cone and the ends of the rudder frame/spines. Heat up the end of the 1/4" x 13" rod until it is red-hot. Hammer the hot end against the anvil and taper or draw out the rod to a point. Re-heat and bend the corkscrew shape (figure C) with round nose pliers and a hammer on the anvil. Clean fire scale off of forged steel with a wire brush.
10. Fabricate and weld bicycle elements into a windmill framework: Note: Safety equipment for welding include: an arc welding hood, safety lenses, leather coat, and gloves.
- Flat bar is welded at a right angle to the flat side of the channel about 3/8 inch from end.
- Channel is welded on the front and center of the steering headset on a vertical axis alignment (figure D).
11. When the bike frame components are assembled, clean all old paint and rust away.
12. Take what was the front forks tube and weld a 1/2" x 1-1/2" coarse thread bolt onto the bottom of the pipe. This will be the mount to the top of the mount pole.
13. For the mounting pole start with a five feet length of 1/2 black steel pipe.
- Weld the 1/8" x 1" x 3-1/2" flat bar steel to the pipe 30 inches apart on center.
- Then weld a 1/2-inch nut to the top of the pole on center.
- Paint the pole flat black.
- Mount the pole to a fence post with 1/4"x 2" lag screws.
14. Weld rudder "spines" to the bike frame tube just in front of the flattened tabs, inline with the vertical axis of the windmill. Shape the spines to form the top and bottom edges of the moon silhouette (figure E).
15. To make the tail design (moon), lay the windmill rudder flat on 22-gauge sheet metal and trace with a black marker the shape of the rudder spines onto the sheet metal. Draw the face of the moon freehand. Make sure that all the surfaces are clean and free from fire scale and rust.
16. Paint the frame with a coat of primer and two coats of desired color. Wear gloves, respirator and eye protection and spray outside.
17. Patina the rudder tail. Spray it with a 10 percent acid solution. The mixture is 5 to 10 percent muriatic acid to 100 percent water. Important! Never add water to acid. Always add the acid to the water.
- Put the solution in a spray bottle and spray it on both sides.
- Wait until it's dry then spray it with a little hydrogen peroxide then wait a day.
- Repeat until desired patina (rust) is achieved.
- Clean it by sprinkling baking soda onto the metal and dip a nylon scrub brush into water and gently scrub the surface. This will neutralize the acid and stabilize the rusted surface.
- When dry, seal with clear lacquer spray paint.
18. Install the rudder into the frame using the four copper tabs and pop rivets. Bend the copper around the 5/16 rudder spines and flattened to sandwich the sheet metal moon. The 1/8-inch copper pop rivets hold these three pieces together on the framework (figure F).
19. Cut out the propeller blades, disc sand the surface pattern, clean edges and bend lengthwise to a concave shape (figure G). Augment and reshape propeller "Hub" to fit blades.
20. Clamp blade on the center (in place) and drill four-equally spaced 1/8-inch holes along the hub chain sprocket for the copper pop rivets with washers. Pop rivet together.
21. Weld the nose cone onto the propeller hub 1-inch off-center of the axial. The tip of the nosecone should be adjusted to be on-center. Put the axial into a vice and put the propeller on and spin it to see if it is balanced (figure H).
22. Reassemble the kinetic components. Make sure the parts are clean and free of dirt. Repack all bearing races with new grease and put all the parts back together (figure I).
23. The mounting pole is meant to be bolted to an existing fence post in the garden. Install the pole high enough to clear all foot traffic. Make sure the pole is plum vertical. The bolt on the bottom of the windmill screws into the nut on the top of the pole. Install the pole then climb a ladder and install the windmill.