Thursday September 30, 2010
Today the class had to build an electric motor.
The materials we used were, a power supply, paper clips, an axle, commutator pins, cork, armature wire, nails, thumbtacks, strips made from aluminium cans, and magnets.
The motor itself was made out of a cork tap, and coil wrapped around it.
Wire was filed at the ends and twisted around the cork. The ends were filed down, so the wire would conduct electricity at the part where it was connected to the commutator pins.
The motor was stuck on an axle and supported up by paper clips.
Commutator pins were placed at ends of one of the faces of the cork tap in a way that when the cork span, the two commutator pins touched the aluminium strips (brushes). The purpose of the aluminium and the commutator pins was to pass on a current which made the motor spin.
When we wound the piece of wire around the cork tap we were able to use up most of it, however we had to cut a small portion. If we used more of the wire, the motor would have spun more easily. It is possible that the ends of the wire were not touching the commutator pins, or were not properly sanded down, which caused the current to not complete its circuit.
When we nailed the four inch nails, we left too much space and had to re-hammer them closer together, so the magnets would stick. We did not hammer them down very well, and the construction was unstable.
There was another problem with our motor. The strips of aluminium we cut out were too long and thin. They ended up getting caught in each other on top and not touching the commutator pins properly.
The commutator pins we used were too short. They did not contact the aluminium strips. When they were in the cork far enough to be stable, they did not reach all the way to the aluminium strips. We realized we needed to improve the motor.
Tonight we will work on rewinding the coil, and filing down the wire to make sure that the current is passing through the motor so it can spin. We will also cut out more stable strips of aluminium and longer commutator pins, so that they contact each other.
Also we will add something on the ends of the axle so that the motor does not move up and down the paper clip supports. We want to make sure the motor spins at a stable spot, so that it touches the aluminum strips, every time it makes a turn.
Another change we will make is to make the holes inside the paper clips larger, so that they offer less resistance to the axle of the motor when it spins.
Hopefully by making those changes, our motor will work and everything will be fine with our motor.
One thing that we did nicely was to keep our board clean and organized. The motor was attached on the axle nicely. The paper clip supports were even.
Motor principle refers to the force produced between a magnet and an electromagnet. An important application of this principle is the electric motor. It directs electric force full circle.
These are pictures of our motor in the process.
Sunday October 3, 2010
By Friday, we had completed our motor and tested it in class. We were excited to see if the improvements we worked on would really make our motor work more smoothly and perform better.
When we attached the magnets and power supply we were disappointed because our motor did not spin.
At first we thought the problem was with the strips of the soda can and the coil. We were about to take off the coil and sand the edges better to allow for better conductivity, when Mr. Chung found out that there was something wrong with the wires used to connect our motor to the power source.
We were happy that our hard work payed off.
This is a picture of our completed motor before we tested it. It was spinning very smoothly.