DC Brush Motor for Learning Fun

A friend has a young son who is newly fascinated by motors and electrical things. This Instructable replicates a DC electric demonstration motor I made about two decades ago for my own children. It is offered here for the sake of parents and teachers like my friend who want to help young people build such things and learn, even though an electric motor may not be part of the previous experience of the adult helping the young person. I am purposely using only common hand tools so anyone could make this for his or her own children. The materials used are also very easy to obtain. The final product is designed to work reliably for a long, long time.

If you would like to read a bit about how electric motors work, go to step 19. I did not put that information in the earlier steps because some important concepts must be discussed first.

Materials used--

3 inch finish nail or thin steel rod
1/4 inch steel rod (a 1/4 inch carriage bolt from the hardware store would do and costs very little)
Electrical tape
Cellophane tape
Masking tape
Plastic tubing for a fish tank or medical equipment
Enameled magnet wire about 24 gauge (Spools of magnet wire can be bought at Radio Shack, or magnet wire can be salvaged from a number of devices that no longer work, like old transformers or motors. Be careful about going into an old television set. While you can find wire there, you can also encounter a lethal dose of stored electricity.)
#12 copper wire (from some old household electrical cable)
Thin stranded wire to connect the batteries
Spring clothes pins for holding the connecting wires in contact with the motor
Dowel rod (1/2 inch)
Wood for a base
Thin brass sheet or brass hobby tubing
Steel wool
Sandpaper
Epoxy glue
Two ceramic magnets
Hot glue
Batteries or a 3 -- 6 volt AC/DC power supply (2 "D" batteries, a battery holder is suggested)
Motor oil (just a few drops)
Pan head sheet metal screws (two)


Tools used--

Electric hand drill and drill bits (a 1/2 inch spade bit is the best, least expensive option for the larger holes)
Center punch and hammer
Vise
Grinding wheel or a concrete face for grinding
Hacksaw
Pocket knife
Ruler
Solder gun or iron
Hot glue gun
Fine-toothed handsaw for wood
Files for metal
Wire cutter
Screwdriver
Multi-meter (helpful, but not necessary)

Step 1 The armature shaft

Begin by selecting a finish nail about 3 inches long. Try fitting it to holes in a drill index to find a bit approximately the same size as the diameter of the finish nail.

Comments

[mathieulj]

Very nice thank you.

[Phil B]

Thank you for looking. I tried to make it so just about anyone could reproduce it for himself from fairly common materials. Kids think it is great.

[WWC]

I Very nice. I have a question about construction. When you soldered the coil leads to the to the brass conductor pieces did you solder the two leads from one coil to the same conductor piece and then the second coil leads to the second conductor to the second conductor piece? So each coil and brass conductor are there own separate circuit with no path between the two?

[Phil B]

There really is only one coil wrapped partly on one half of the metal core and wrapped partly on the other half of the metal core. The one coil yields two wire ends to be soldered to two brass conductor pieces. Let me know if you still have questions. Thank you for looking and for commenting.

[WWC]

Ok I think I got it. There is only one wire not two like i was thinking. Thanks for your help!

[Phil B]

You are correct--only one wire with two ends. When winding, I wound one layer out to the end and back, then I crossed the wire over to the other side and did the same. Then I went back to the first side and wound out and back, then back to the second side again. As I mentioned, it did not balance when I was done. So, I removed about 30 turns from the first side by unwinding wire and wound all of it back on the second side. There is no magic in the number 30. It was just a first attempt at moving enough wire from one side to the other to make the armature balance.

[steliart]

Wow!!! Brings back memories :)
Excellent instructable and very detailed as always Phil.
Thank you

[Phil B]

Thank you, Steli. Kiteman recently published an Instructable on how to write and publish Instructables. In it he mentioned school classrooms sometimes use an Instructable for teaching purposes. I hesitated to do this until my encounter with my friend whose son is suddenly interested in electricity combined with Kiteman's comment. I do not know if you had 4-H Clubs on Cyprus when you were growing up, but I was in one in my home state of Iowa here in the USA. They had some project bulletins for things people might exhibit at the local county fair. One was a DC motor using a commutator and brushes, but that was in the days before cheap ceramic magnets and those plans called for electro-magnets in the field. A key feature of those plans was that all of the steel parts were from a couple of sizes of common nails held together with electrical tape to make the armature and the field, as well as the supports for the armature. I made one, but modified it quite a bit. I bent some strap iron for the field. That motor worked, too. I think my brothers and I powered it with the transformer from a toy electric train.  I expect you must have built something similar as a boy.

[steliart]

I remember when I was a kid we did some similar projects in science class, but soon after I changed my direction towards what we call the classical studies, ancient Greek and Latin languages, History, Philosophy etc., so I can’t claim to remember today much of that science stuff. But I do remember few main things of it LOL that’s why I commented that it brings back some memories :)

[Phil B]

It is too bad you had to choose between languages, etc. and science interests. My high school offered only a couple of years of French. I was planning to become a pastor and would need to study German, Latin, Koine' Greek, and biblical Hebrew. Someone told me those who do well in science and mathematics also do well in languages. I liked science and mathematics, and found I also enjoy languages.

[Dipankar]

Very good Phil, Beautifully explained.
I would get tired from writing such a big article, but you are great.
Thanks.....

[Phil B]

Thank you. I really enjoy explaining something so someone else can use it.

[rimar2000]

Perfect as always, Phil!

[Phil B]

Thank you, Osvaldo. I am glad you enjoyed it.