Nixon Elementary School Noon Science
Electric Motor Instructions
Tony Alfrey
tonyalfrey@earthlink.net
Science experiments at http://homepage.mac.com/tonyalfrey
We’re going to make a simple electric motor from (mostly) readily-available materials!
Our motor is based on a design that you can find on-line, the so-called “Beakman Motor”
(http://fly.hiwaay.net/~palmer/motor.html). Here is our version of the motor.
Figure 1. Our version of the “Beakman” motor, made from paper clips, sticky tape, magnet wire, a button
magnet and a D-cell.
The motor consists of an armature (the part that spins around) and a frame (the part that
sits still, holds the magnet and bearings for the armature and holds the D-cell battery
power source). The armature is the most difficult part for children to build; it requires
some care to get it balanced properly. Additionally, we’ve developed several different
versions of the armature; we’ve included the instructions for one version and we’ll soon
post the instructions for another version.. We hope that you can help your child build one
of these versions so that he/she can bring it to our Noon Science session for installation
into a completed motor. We will build the frame in the Noon Science session. If you’re
reading a printed copy of this, perhaps your child has brought home some special wire
(and these instructions) that we’ll use to make the armature. See a short video of our
motor and color documentation at http://homepage.mac.com/tonyalfrey.
The Armature
Materials for the Traditional “Beakman” Armature.
1. 54” of #24 gauge magnet wire. This wire is solid copper, with a tough, enamel
insulating coating that can be scraped off. #26 gauge wire (smaller diameter) is available
in a set of three rolls of magnet wire from Radio Shack (#278-1348). My personal taste
is that the #26 wire is a little too flexible, but you can experiment with different gauge
wire. However, do not substitute a different kind of wire (such as conventional vinylinsulated hookup wire) for the enameled magnet wire.
2. Piece of fine sandpaper or pair of scissors (for scraping off the enamel insulation on
the magnet wire). The scissors are also useful for trimming the wire “tails” of the
finished armature.
3. A conventional D-size “battery”. We’ll use this as a form for winding the armature.
Later, it can be used to power the motor.
4. A pair of small cardboard pieces (about 6” x 3”) for holding and transporting the
finished armature.
5. Scotch tape or masking tape (for sealing up the cardboard used to transport the
armature to Noon Science).
Making the Armature
This is the hardest part of the whole project and requires the most adult assistance for
younger children.
1. Refer to this picture as you follow the instructions. It shows circular loops of the
magnet wire, with the ends carefully wrapped around the sides of the loops to secure the
loops in place. The wire “tails” sticking out from the sides are lined up with each other
and divide the loops in half.
Figure 2. The “Beakman” armature of ten turns or “loops” of #24-gauge magnet wire, about 1 ¼” in
diameter. See how the “tails” are secured to the loops with a few extra turns around the loops.
2. Start by taking the full length of #24 gauge magnet wire and pulling it through your
fingers to slowly remove the bumps and kinks in the wire. Do this several times.
Figure 3. Smoothing the magnet wire.
3. Wrap 10 turns of wire around your D-cell battery, Start winding a few inches from
the end of the wire. Wrap the turns close together as you wind the wire.
Figure 4. Winding the armature.
4. Carefully slide the loops off of the D-cell as a group.
Figure 5. Holding the loops together.
5. Wrap one end of the wire tightly around the loop. Three or four tight turns is
sufficient. When finished, the wire sticks out away from the loops like a “tail”.
Figure 6. Securing a tail to the armature. Hold the loops as a bundle and tightly wrap the tail around the
loops about three times.
6. Now do the same for the other end of the wire, making a tail that sticks out in the
opposite direction from the first tail.
Figure 7. Secure the other tail.
7. Cut off the tails so that they are about 1” long.
Figure 8. Cut the tails to 1 inch.
8. Carefully place your wound armature flat onto a table. With the armature in this
position, scrape off the enamel insulation from ONLY THE TOP SIDE of the “tail”
sticking out from the right side of the armature. Scrape the surface of the tail that is
parallel to the surface of the table. You can use sandpaper, a sharp knife or the edge of a
pair of scissors for a scraper.
Figure 9. Removing insulation from the tails. The left figure shows how to scrape off the insulation with a
knife. Drag the blade to the end of the tail. The right figure shows how the insulation is removed from the
top side of the RIGHT tail, but not the bottom side. These views are shown looking toward the end of the
tail.
9. Next, scrape off the insulation from ALL AROUND the left tail (like peeling a carrot).
10. Straighten out and smooth the “tails” so that they lie along a line.
11. Carefully balance your armature on your fingers so that it does not flop to one side
too much. Slide the tails (where they are wrapped around the loops) a little at a time and
test the balance each time you make a change by giving it a little spin. We will help the
children balance the armature when they come to Noon Science. We also show this
briefly on the video of the working motor (see the link at the end).
12. When you are satisfied with your work, sandwich the armature between two sheets
of cardboard so that your child can bring it to Noon Science without damage. Seal it up
with a piece of tape.
If you have some problems with your armature and you need to start over, send me an email (tonyalfrey@earthlink.net) and we will arrange to have more wire available for pickup in the library.
The Frame
Materials
We will build the frame in Noon Science. But if you’d like to follow along, here are the
materials and instructions we will use.
1. One D-cell “battery”.
2. Two pieces plastic-insulated, #26 gauge solid hookup wire, cut to 6” long, with 1” of
insulation removed from each end.
3. Three “jumbo” paper clips (roughly 2” long x 3/8” wide).
4. Nine double-stick, foam “Mounting Tape” pads, ½” x ¾”. Scotch-brand #110 or
equivalent. The foam pads are sometimes available pre-cut (as I am holding) from other
vendors and hardware stores (Ace Hardware #90969).
5. A mounting board, made from a piece of 6” x 8” foamboard, stiff mattboard or other
stiff cardboard.
6. One button magnet, approximately ½” in diameter by ¼” thick (#07002, Master
Magnetics, Inc. www.magnetsource.com).
Figure 10. The materials for the frame.
Making the Frame
1. Re-shape two of the paper clips as shown in the sequence of pictures below. There is
a “left” and “right” clip.
A “left” clip. Bend the arm out to the left . . . .bend the middle up to the right . . . . . .and add a “U” bend.
A “right” clip. Bend the arm out to the right . . . .bend the middle up to the left . .. . . .and add a “U” bend.
Figures 11 and 12. Bending the paper clips into bearings.
2. Wind the uninsulated end of one hookup wire around each paper clip as shown below.
Figure 13. Adding hookup wire to the bearings.
3. Place the two paper clips 2” apart on the base like this:
Figure 14. Place the paper clip bearings on the base.
4. Use two pads of mounting tape to stick the paper clips to the cardboard base as shown
in the picture. These will serve as “bearings” for the armature.
Figure 15. Use the sticky foam mounting tape to attach the bearings to the base.
5. Clean the “U” at the top of each bearing with some sandpaper so that a good electrical
connection will be made between the armature and bearing.
6. Bend another paper clip in the sequence shown below.
Figure 16. Bend a paper clip for the magnet support.
7. Stick the paper clip to the cardboard base as shown in the picture. Place the clip 1”
from the center of the two paper clips you put down previously.
Figure 17. Install the magnet support paper clip.
8. Use a piece of foam mounting tape to stick the D-Cell to the cardboard base.
Figure 18. Install the D-Cell.
9. Connect the hookup wires to the ends of the D-cell using two more pieces of mounting
tape. Make a loop with each end of the uninsulated wire and place it in contact with the
metal contact of the cell.
Figure 19. Attach the hookup wires to the ends of the D-Cell.
10. Stick a magnet to the paper clip as shown below. Don’t use any tape; the magnet
sticks by itself.
Figure 20. Add the magnet. Your motor frame is ready!
11. Carefully install your armature onto the paper clip bearings and give it a gentle spin.
It will try to turn in one direction; you may need to test each spin direction to get the
motor started.
12. Come see a video of our working motor on-line!
http://homepage.mac.com/tonyalfrey
Hints for making your motor work well.
1. It is very important to balance the armature. Make sure that the “tails” are straight and
make sure that the armature spins freely without favoring one side or the other.
2. Clean the surfaces of the tails from which the enamel has been removed. Sparks on
the wires corrode the copper after the motor is used for awhile! (look at the tails with a
magnifying glass to see if you can find the corroded spots). Also, clean the surface of the
paper clip “bearing” on which the armature “tails” rest.
3. Move the magnet as close to the armature as possible without letting the magnet and
armature collide. Also experiment with the best vertical position of the magnet. The
magnet will slide up and down on its paper clip.
Other experiments to try.
a. What happens if you turn the magnet around? What happens if you turn the
armature around (switch the left and right sides)?
b. Try adding another magnet on the opposite side of the armature. Does it make
a difference which way the second magnet is oriented?
c. Try using a bigger magnet.
d. Try using a different number of turns of wire. If you make an armature with
many turns of wire, it helps to hold the tails in place where they wrap around the loops by
using a bit of glue from a hot glue gun.
e. Try using heavier or lighter wire. We find that heavier wire, while easier to
manipulate and less fragile, does not work as well (and we have a theory why). What is
your theory?
f. Can you think of a different way to remove the insulation to make the motor
work with the magnet lying on the base, under the armature, instead of on the side?
How it works (a mixed kid-level and adult-level explanation).
Think of how a magnetized compass needle points in the direction of the Earth’s
magnetic field. When the motor armature is aligned parallel with the base, and with the
cleaned side of the magnet wire touching the bearings, current flows through the wire.
This creates a small electromagnet, like a “compass needle”, pointing up. The stationary
magnet fastened to the side plays the role of the Earth, with a magnetic field pointing
sideways. The “compass needle” loop is then turned to line up with the magnet field of
the stationary magnet “Earth”. At this point, the electrical connection between armature
and bearings is broken and the armature “compass needle” disappears. The loop
continues to spin around by it’s own momentum, until it once again lies flat, becomes a
magnet again, and gets another pull.
Rev. 03/05/05