Electric Motors

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Building and Improving aSimple Electric DC Motor
Bill Kuhl http//www.scienceguy.org
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Background
A motor of similar design appeared on the
Beakman's World TV show and many people refer to
this motor as Beakman's motor. This is not a
true electric motor in that electricity is just
turned on and off, the polarity is not switched
within the coil as in more advanced motors.
In this project, besides demonstrating
principles of magnetism to create motion, I
wanted to get across how I improve upon similar
projects. To do this I looked at how other people
have designed this simple electric motor,
discovering possible weaknesses, and trying to
improve on those weaknesses in my design.
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Possible Weaknesses in Design
Poor Battery Connection
Support Bracket
Long span between support brackets can be a
problem.
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A Couple of Definitions
The straight and coiled segments of wire I will
refer to as the armature.
The bracket that holds up the armature and acts
as a brush, I will refer to as a support
bracket.
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Possible Weaknesses in Design
Contact Area is Too Small
I found the contact area (brush) was too small
with this design and the armature would often
stop turning. Reliable operation should be the
goal in all of your projects.
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Looking at Other Ways to Design This Motor
This kit version of the Beakman motor worked
pretty well but has a long span between the
armature supports and the contact area is too
small. Battery contact was good because the
battery was pressed firmly against the contacts
which were also the armature supports.
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Support Bracket
In a bottom view of this motor it can be seen
that the D-cell battery snaps firmly in place
against the bottom of the support brackets.
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This is the first version of a simple motor that
I built. Fastening the supports for armature
with masking tape is not a good idea. It did run
for a time and then would require adjustments.
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This motor was in a kit of more inventions. The
battery connection method was not the best but
the armature shaft did not span a long distance
un-supported.
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My Version of the Simple Motor
First prototype of my version of the Beakman
motor. The battery is clamped tight between the
copper-coated clamp pieces and the armature
supports are moved closer together.
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Tabs give more area for good contact.
Kevin Guy, the hobby guy gave me the idea to bend
tabs over to give more area of contact, it works
great!
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I came up with the idea of gluing small beads on
each end of the coil so the armature would not
move horizontally. The glue also firms up the
armature portion of the wire coming from the coil.
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Materials
The following are pictures and descriptions of
the materials I used to complete this project. I
made an effort to find materials that could be
found in almost any city at a reasonable price.
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I found a real deal on ceramic magnets, 51
magnets for 6 at a store that sells mainly
tools. Northern Tool Equipment
http//www.northerntool.com
Radio Shack also sells ceramic magnets in smaller
quantaties.
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This 100 count bag of sheet metal screws would
supply enough screws for 25 motors. The large
head on the screw holds the brackets down firmly
and screws in easily to the pine wood once a
starter hole is drilled.
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I cut these copper plated tube straps in half to
create the brackets used in the motor, two straps
per motor needed. At lumber supply store I saw
the straps in 10 or 100 count bags.
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Pine board 3 ½ wide by ¾ thick makes a good
base for the electric motor. The board will be
displayed as 4 by 1, I found these boards 4
feet long for under 1.
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I used hook-up wire to connect battery brackets
and motor brackets. The red insulation is to
indicate positive and the black to indicate
negative. Color coding not needed for this
project but I feel it is good to develop a habit
of marking polarity.
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Radio Shack sells 3-pack of enamel-coated magnet
wire, I would suggest using the heaviest wire
which is the 20 gauge.
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I used craft beads to keep the armature (straight
sections of the wire) from moving from side to
side while running.
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These Mounting Squares which are double-sided
sticky tape provided and easy method to attach
the magnet yet the magnet could be removed later
with some effort. Magnets could be glued to wood
base also but would be harder to remove later.
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I found these bargain priced Phillips
screwdrivers for .70 a piece. The quality seems
fine for this project.
Tin snips can probably be found for under 12
where tools are sold.
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Wire Strippers can be found at Radio Shack or
other stores that sell tools.
Low temp hot glue guns are normally found where
craft supplies are sold.
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File to file off sharp edges
Saw to cut wood base
Sandpaper to remove enamel coating on wire
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Building the Motor
For each motor, cut two of the tube straps in
half, this will make four brackets.
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The curved portion of the tube strap halves are
easily straightened in a vise.
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If you do not have access to a vise, the material
could probably be straightened with a pliers or a
hammer.
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(Left Picture) side view of two brackets that
have been straightened. (Right picture) Back of
two brackets that have been marked for two slits
to be cut so tabs can be bent.
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¾ to bend
(Left Picture) Cutting one of two slits, stop at
horizontal line. (Right picture) bending the tab
back the same direction as the bottom part of
bracket.
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(Left Picture) Tab has been bent over, now make
sure the other two strips of the bracket are
vertical. (Right Picture) Trim off some of the
material, only about 1/8 needs to stick up above
the tab.
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It is easier to strip the insulation off the wire
when you have something to hold on the other end.
I strip insulation off on one end, and then cut
the wire. The wire should be around 3 inches
long, ½ inch of insulation stripped off on each
end should be good.
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Wrap the wire 15 times around 5/8 wood dowel,
leave around 3 extra on each end of the wire.
The number of loops is something that can be
experimented with, try a few more or less, then
observe change in speed.
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(Left Picture) in the middle of the loop one each
side, wrap the wire around the bundle of wires a
couple of times. (Right Picture) This is what the
coil should look like now.
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(Left Picture) Mark the block 3 from one end.
(Right Picture) Cut across the wood. Hand saw
cut through the pine wood very quickly.
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Mark where the bracket holes for the battery will
go by using a D-cell battery as a guide. It will
be a tight fit on the board. The holes in the
bottom of the brackets are large enough that
there is room to adjust the bracket some to get a
tight fit to the ends of the battery.
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(Left Picture) Drill the starter holes for the
screws a little smaller than the screw and not
all the way through the board.
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(Left Picture) It is a good idea to file any
sharp edges on the brackets.
(Right Picture) Screw in brackets so that they
are tight to the battery.
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(Left Picture) The straight section of wire on
one side of the coil can be sanded completely
around the wire. (Right Side) On the other side
only sand off the coating on half of the wire.
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Looking at Cross Section of Wire for Half Sanded
Side
Enamel Coating
Copper Wire
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(Left Picture) Glue the bead being careful not to
get glue on the outside edge of the bead where it
makes contact. (Right Picture) The completed
assembly should look like this.
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(Left Picture) the brackets that support the
armature need to be positioned so the armature
fits between with a tiny gap on the outside of
each bead. Screw in one bracket, and mark the
hole for the opposite bracket. (Right Picture)
The battery connection wires are bent in a half
loop and put under the screw head as you tighten
it down. Un-insulated portion of the wire is
placed under the screw head so that the half-loop
tends to curve with the direction the screw as
tightened.
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(Left Picture) Place the sticky side of the
double-sided tape on the wood base between
brackets, then peel the backing off. (Right
Picture) Place the magnet centered on the sticky
tape.
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Completed motor in action! You will probably need
to give the coil a gentle shove with one finger
to start it in motion.
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Further Experimentation
Once you have a project working, it is fun and
educational to try new adjustments to try to
improve performance. Sometimes what you try
might not work as well. You might consider

• Make a new armature/coil with more or fewer
  windings.
• Adjust the gap between the magnet and the edge
  of the coil to be less but not touch at anytime.
• Try a stronger magnet such as a neodymium magnet.

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If Your Motor Doesnt Run
Dont get upset, troubleshoot the problem. You
will probably learn more if your project does not
work perfectly from the start. Make sure

• All the connections between the battery and the
  motor are solid.
• The armature wire is as straight as possible.
• The enamel has been sanded properly, half the
  diameter on one side and around the entire wire
  on the other side.

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http//www.scienceguy.org
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