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MendoMotorProcess

Page history last edited by PBworks 14 years ago

The mendocino motor is a magnetically levitating, solar powered motor. The motor was invented by Larry Spring of Mendocino California in 1992. In my Principles of Technology class students have been building the motor since 1999. The motor project introduces students to a variety of important processes, techniques and tools.

 

The way I teach the project, first students learn a Computer Aided Design software package such as ProDesktop or Sketchup, then they design the parts of the motor, building each part to the measurements, then assembling the parts into a final document. Next students are introduced to measuring and cutting with a hand saw, then a cutting with a power miter saw. When the base and upright are cut, they then use the router table to cut grooves into the base. The upright is butt jointed to the base, then a little light sanding followed by a few coats of polyurethane.

 

During the periods that the base is being polyurethaned, students make the rotor block using a special jig for the router table. The block is 2 inches long, 1 x 1 with quarter inch grooves on each corner. Next students measure out 2 50 foot lengths of magnet wire by wrapping it on a 1 foot paddle. The block gets a 3/8" hole in the center, then a 8 inch dowel is inserted into the hole.

 

Wrapping the motor with the magnet wire involves carefully wrapping the wire in the grooves around the block 100 times in sets of ten alternating on each side of the dowel. The wires are then labelled and confirmed with a continuity tester.

 

Solar cells are then glued and taped into place on the sides of the block. The cells on opposite sides are soldered to each other, front to back and front to back. Each end of a wrap wire is soldered to a connection of solar cells.

 

At this point, there needs to be a bearing in the end of the end of the dowel. Using the drill press, students put a hole in the end of the block, then a brass tack is put into the hole.

 

At this point, the motor is ready for assembly and testing. Glue a mirror to the upright, then put the ring magnets into the grooves. The magnets probably will not sit in the grooves, so you shim them into place with paper. The magnets need to be south pole facing in, you determine the polarity of the magnet with a compass.

 

The magnets will not stay in place without a little tape on the dowel. The front magnet on the rotor is centered on the front magnet on the base. The rear magnet on the rotor is centered on the center of the pair of magnets on the base.

 

Next is balancing the rotor. If the rotor is out of balance, it will not have enough energy to lift the heavy side, so it will not spin on its own in the light.

 

Test the balance by turning the rotor 1/4 to a half turn and letting it go. Spinning the motor doesn't tell you much. When you let the rotor go, it will probably settle down consistently with the heavy side down. Add a little solder to the area that is at the top. Having some tape around the cells comes in handy here, because you can slide the solder between the wrap wire and the tape. Add enough to make it balanced, but not so much that you overcompensate.

 

When the balance is about right, put it into the light. Incandescent light works, but flourescent doesn't. If it doesn't work, check the MendoTroubleshooting guide.

 

Get the motor running right and it should spin on its own whenever it is in the presence of sunlight or incandescent light.

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