DC Motor

Project Goals

For this project, we are designing and constructing DC motors. They are not going to look like the one above, but they will function better if we succeed. Our project goal is to build a motor that can lift a 450 gram weight 14 feet. We will have 1 pound of magnet wire and other resources. We will learn how to design parts of our motor using CAD/CAM and we will have a deep understanding of many aspects of motors by the end of the project.

The learning goals are understanding multi-meters, electricity flow, power, efficiency, and how to analyze our results. With this knowledge we will be able to not only design our motors but analyze motion to see what level of success we reached.

The Steps

The first step in this project was to design supports for the bearings that will hold the shaft that spins. To accomplish this goal we used a professional level engineering software program called SolidWorks. We took many days of hard work to design not only a functionally solid support but also something that llooked good. We designed ours with many triangles to add structure and strength. The only problem we encountered was we designed the screw holes for the shaft diameter instead of the thread diameter. We were quickly able to fix this by drilling the holes bigger.

Here is one of two finished bearing supports that would later be fixed onto the base. It has the bearing

which was a perfect push fit and screws ready to be drilled in.

The next step was to fix one support to our base.

The next steps were to make the armature. To do this we drilled a hole large enough for the axle in a large bolt. Once the hole was drilled, we tried to insert the axle into the bolt. At this point, we encountered a problem. The axle did not want to slide in to the bolt and the bolt bent. After lots of trial and error. We got the axle secured in the bolt with JB Weld.

Now we could begin wrapping the complete armature in 63 feet of magnet wire. This process took a long time as we wanted to make it a tight wrapped coil. The picture below shows the wrapped armature inserted into the bearing supports. It spins very well with little friction, just like we wanted.

This is a picture of my stator welded.

Once again we needed to wrap magnet wire. This time to be more efficient I created this setup to make the feeding of the wire hands free.

Once the stators were wrapped, welded on base plates and ready to go, we mounted them on our board with three screws each.

This is a video of us spinning our armature. It could not be propelled with magnetic forces yet, but it was still a success to have it spinning at all.

Next we needed to begin working on making the motor work. The first step was designing commutator plates. They are needed to switch the direction of the flow of electricity. We used a torch to solder wire to a half piece of copper pipe.

After that, we made brushes, small pieces of metal that carry the current to the commutator plates. We had some difficulty making brushes that performed well, but eventually made some that worked well. Finally, after lots of trial and error and troubleshooting, we were able to successfully pull the 450 gram weight. The few main problems were our wiring was just off and need some adjustment and the final small change we made was decreasing the gap between the stators and the armature. This was the fix that helped our motor the most.

The Final Test

Here is the video of our motor accomplishing the goal of pulling a 450 gram weight 14 feet. Our motor was not the fastest, but it met the project goal.

Conclusions

This project I learned a lot of informal lessons. One I learned is that box-head screws are not the smartest choice because they are not as common and there aren't many screwdrivers for them. Another informal lesson I learned is sanding down the enamel completely on wire is very important. Any small bits of enamel can hurt the performance of the wires. Lastly, I learned that doing things once but with more care will save time in the end and turn out better. With our brushes we had to redesign twice because I wasn't being as precise as I could have been. If I started over from the beginning, I would figure out a way to wrap the wire tighter. Tight wrap seemed to directly correlate with strong motor performance. I would also use a larger piece of wood. This was a fun project. We got to work on the computer, with wood and with metal, which was very interesting. Mixing three or four types of materials was sometimes a challenge, but it was realistic. Troubleshooting the motor at the end was difficult, but it was good to have to problem solve. The only thing I disliked about this project was the wrapping and stripping wires was tedious, but it's just part of being a good craftsman. Overall, I don't have any improvements to recommend for this project.