Http:// Bill Kuhl

Bill Kuhl http://www.scienceguy.orghttp://www.scienceguy.org

BackgroundBackground

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.

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.

Long span between support brackets can be a problem.

Support Bracket

Poor Battery Connection

Possible Weaknesses in Design

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”.

Contact Area Contact Area is Too Smallis 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.

Possible Weaknesses in Design

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.

Looking at Other Ways to Design This Motor

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.

Support Bracket

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.

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.

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.

My Version of the Simple Motor

Tabs give more area Tabs give more area for good contact.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!

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.

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.

Radio Shack also sells ceramic magnets in smaller quantaties.

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

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.

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.

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.

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.

Radio Shack sells 3-pack of enamel-coated magnet wire, I would suggest using the heaviest wire which is the 20 gauge.

I used craft beads to keep the armature (straight sections of the wire) from moving from side to side while running.

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.

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.

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.

Saw to cut wood baseFile to file off sharp edges

Sandpaper to remove enamel coating on wire

For each motor, cut two of the tube straps in half, this will make four brackets.

Building the Motor

The curved portion of the tube strap halves are easily straightened in a vise.

If you do not have access to a vise, the material could probably be straightened with a pliers or a hammer.

(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.

(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.

¾” to bend

(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.

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.

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.

(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.

(Left Picture) Mark the block 3” from one end. (Right Picture) Cut across the wood. Hand saw cut through the pine wood very quickly.

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.

(Left Picture) Drill the starter holes for the screws a little smaller than the screw and not all the way through the board.

(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.

(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.

Looking at Cross Section of Wire for Half Sanded Side

Enamel Coating

Copper Wire

(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.

(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.

(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.

Completed motor in action! You will probably need to give the coil a gentle shove with one finger to start it in motion.

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.

If Your Motor Doesn’t Run

Don’t 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.

Be sure to check out my website for more projects http://www.scienceguy.org

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