Convection Powered, Counter Rotating, Kinetic Sculpture





Introduction: Convection Powered, Counter Rotating, Kinetic Sculpture

Powered by Sterno made of wood, sounds like a recipe for fire. It took two cans of heat to get it moving the first time but continued to spin almost as fast after removing one can. It serves no purpose yet but tomorow I'm going to add a pot- pouri jar just under the rotor blades to give it
 reason for being. I'll call it counter rotating pot-pouri diffuser.
I'm working on downloading a driver for my video cam so you can see it in action.


Step 2:

Step 3:

Materials used:
1/4" x 5.5" x 48" poplar
.037" x 12" x 24" birch plywood
1/2" x 5.5" x 24" poplar
1- 4" long shawl pin
4- 1/8" plastic beads
Titebond III wood glue
1- Corel saucer

Tools used:
Epilog laser (other methods of cutting are possible)
cordless drill
small paint brush
small vise grips
small spring clamps
small square



Step 4: Assembling the Rotor Rims

I built a jig to assemble the rotor rims using a very flat support board, a 1/8" thick plywood circle the inside diameter of the rotor's 1/8" plywood rings. Made a clamp from 1/8" plywood to hold the .037" thick birch plywood to the 1/8" rings. When gluing up everything stay flat and tight. Very little pressure is needed on the visegrips to hold the .037 " plywood tight.

Step 5: Mirror Image the Rotor Blades

Notice the small tabs on the rotors (tips of pencils), the rotor hubs need to be glued so the rotors are mirrored.

Step 6: Assemling the Rotor Hubs

I drilled a hole into my build table ( square with the surface) so the hubs would glue up square.

Step 7: Assembling Rotor Blades to the Rims

The rotor blades are quit thin and very flexible. To assemble them I simply twisted each blade to lock the two tabs onto the 1/8" plywood ring, one tab over the ring, one tab under. I mirror imaged the rotor blades so they would spin in opposite directions. Tension holds them in place, no glue is needed.

Step 8: Assembling Main Support Body

I attatched the support body halves to my build table so when I glued up the ribs and stringers they would remain straight.

Step 9: Adding the Ribs

Gluing on the ribs I used a square to insure they wre too.
note: if you cut with a laser the glue faces need to be sanded square.

Step 10: Installing Rotor Axle to Main Support

I used a small pair of vise grips to support the axle and rotor assembly while the JB WELD cured. 

Step 11: Finishing

Finish by gluing the support to the base and fit the saucer to hold the Sterno can.

Kinetic Sculpture Design Contest

Second Prize in the
Kinetic Sculpture Design Contest



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    40 Discussions

    Hmmm , I wonder about using bicycle wheels for this . I really like your support structure , way cool looking .

    4 replies

    Bicycle rims would surely work if you used enough heat to overcome the weight.

    Oops , I was thinking about the bearings , good point about the weight . There is a project an Aussie inventor came up that works on this principal using solar heat in the out back only on a truly massive scale .

    Do you have a web site where the Aussie inventor has info on his project? Sounds very interesting.

    Call me curious, but will a candle power this? I can imagine that a scented candle burning under this thing could disburse the scent very nicely.

    Congratulations on being featured.

    2 replies

    Thank you, In it's present state a single candle will not provide enough heat. Scaled down to lighten the rotors and bring them closer to the heat scource, quite possibly.

    Because of the nature of bouyancy, if the turbine were more like a drag turbine design (sail shaped sort of) and overlapped foils ever so slightly (12% or so) it might run off a candle. With the low velocity laminar flow coming from a candle it would need be impact driven rather than lift driven. just a thought.

    According to American Hertitage Dictionary:
    1. The act of conveying; transmission.
    2. Physics.
        a. Heat transfer in a gas or liquid by the circulation of currents from one region to another.
        b. Fluid motion caused by an external force such as gravity.
    3. Meteorology. The transfer of heat or other atmospheric properties by massive motion within the atmosphere, especially by such motion directed upward.
    I had to check, wasn't sure of the exact definition myself. 

    Ah ok, thanks. I guess my definition of Convection was restricted to one thing. Thanks for the info :)

    Thank you much. Might be a bit touchy getting it to turn at the proper speed and would need to use mylar for the mirrors to keep the weight down. Excellent idea.

    Yes, didn't get published last night till 11:50pm so I had no time to include a video or the drawings. Will try to get them both in tonight after work.

    yep, but had to choose either a new truck or the machine. Sadly the truck was destroyed in an accident 3 days after ordering the machine.

    Oh I see what happened. You were driving distracted, thinking about your new laser cutter, right?

    LOL, I joke. Hopefully no-one was hurt!