[HighTek]

For one of our final lab projects, we have to (less design and more build) an electric DC motor on a 6V DC battery.

Restrictions/Requirements:
No plastic parts can be used
The motor must run for at least 60 seconds
No simple motors allowed

I was hoping that someone could point me in the direction of some great resources. But judging from the lack of responses one usually gets in this forum, I doubt it. All my research (read: the first 4 pages of a google search) brings up only simple motors. Sooo....any help would be appreciated. I may even post my full report on here when I'm done... at least that will help a future student.

[Borek]

"Simple motor" sounds awfully ambiguous.

[HighTek]

"Simple motor" sounds awfully ambiguous.

It does...so I found out my professor's definition of a "non-simple motor": it has to have brushes and a commutator. If it doesn't have those, its a simple motor. I hope that helps a little.

[Arkcon]

You should try some more Google searches.  FWIW, my child's encyclopedia of science definitely showed how to build your own motor.  But that was just a cookbook -- wind this here, connect that there, scrape the bell wire insulation here, and to form the axle, you flame polished a piece of glass tubing, so no plastic parts back in the '60's.  Sorry to disappoint on the lack of responses, but there's nothing to really learn here -- just a copying of craftsmanship.

Do you know how a motor works?  What parts does it have?  How does it use it's parts to work?

[HighTek]

You should try some more Google searches. 

I have found sufficient information to attempt the design of my DC Motor. Google was the first place I hit an all it returned were sites for "simple" motors. I had to dig a lot deeper. Now I'm gathering necessary materials for construction.

Do you know how a motor works?  What parts does it have?  How does it use it's parts to work?

I'm familiar with the physics behind the motor. It involves creating a an alternating current in loops of wire (solenoid) and a magnetic field. Combined in the proper configuration, it creates a force (torque) sufficient enough to rotate the coils of wire. I have to write up a proper lab report to go along with my DC motor which I plan to post.

[Arkcon]

Good.  Now, look at it this way.  You have a bar magnet, with north and south poles, or at least that's what we call them.  And the opposites attract, and same poles repel.  You can make an electromagnet, by winding coils of wire around an iron bar.  North and south, depending on which way the current flows.  Now, all you have to do is switch current direction, at the right moment, and an armature will spin.  Yeah, a very simplistic explanation, the devil is in the details.

[HighTek]

Interesting. Here is my plan of action (which may be wrong):

The armature will be made up of coils wrapped around a cylindrical lightweight material (possibly cork). A pair of bar magnets will be set up parallel to the cylinder to create the magnetic field. Its a bit hard to explain without a diagram but the wires made from the coils will not be connected directly to a 6 V battery.  Instead, it will serve as a makeshift commutator by attaching the ends of the wire to opposite sides of the amature  "arms." The 6 V battery is going to be attached to a couple of copper strips that serve as brushes which will come in contact with the commutator. This way, I think the current will alternate every 1/2 turn.

[HighTek]

Well, today my lab report is due for the DC Motor.

We had our motor run-off last Friday. Out of about 13 students, only 2 worked. Mine was a complete failure. I suspect my failure was largely due to design. It would turn but the coils turned into a magnet...it repelled my other magnets when connected to the power source (it didn't repel the magnets when it wasn't hooked up).

The designs that were successful were ones pulled from YouTube.

[Arkcon]

So it initially repelled, but then didn't keep spinning?  Bummer.  It was hard, as I recall, getting the commutator brushes just right.  And getting enough field strength to spin at all.  But, like I said, a direct copy of a cookbook is the way to make one spin.  Still, you probably learned more, for trying, than other people did.  Have one on me.

[Borek]

I don't understand - you have no chances to try your design first, and to adjust details after initial failure? That sounds waste of time, usually you will learn more trying to adjust design to make it work than just seeing it was a failure.

[HighTek]

So it initially repelled, but then didn't keep spinning?  Bummer.  It was hard, as I recall, getting the commutator brushes just right.  And getting enough field strength to spin at all.  But, like I said, a direct copy of a cookbook is the way to make one spin.  Still, you probably learned more, for trying, than other people did.  Have one on me.

That's right, the coils just became magnetic, then quit. I'm 99% sure it was my brushes and commutator. And yeah, I learned a lot from researching the design and the magnetic & electric principles. It was just frustrating that the time and effort didn't pay off in that magical tingly warm feeling kind of way.

I don't understand - you have no chances to try your design first, and to adjust details after initial failure? That sounds waste of time, usually you will learn more trying to adjust design to make it work than just seeing it was a failure.

We basically had 1 month to make the motor. The motor run-off was the absolutely final day. We were to make all adjustments to correct the failure before that day. I did learn, its just that I (or we) ran out of time and didn't know how to fix our motors. We tried to help each other out, but it was like the blind leading the blind. The dude who's motor worked had help from a professional.

Oh well, its over. I could post my lab report but then that would just be wrong (in educational terms).