Natasha Dudek          

Science Fair Project

2006-2007

 

 

 

 

 

 

 

 

 

The Wimshurst Machine

 

 

Purpose:

 

 To design and build a fully functional Wimshurst machine which is capable of generating electricity through electrical induction.

 

Hypothesis:

 

If two discs with metal sectors are rotated in opposite directions, and a charge is created by electrical induction, then this energy can thousands of volts (about 70 kilovolts with my design), and can be collected to create sparks.

 

Materials:

 

-wooden plank (34cm x 78cm x 2cm)

-Two pieces of wood (6cm x 24.5cm x  3.5cm)

-Four pieces of wood with dimensions (15cm x 2cm x 2cm)

-Four pieces of wood with dimensions (15cm x 4cm x 1.5cm)

-Two large  Lexan polycarbonate sheets, at least 70cm x 50 cm. (Lexan is General Electric brand  “high-performance low-conductivity”  polycarbonate sheet.)

-Two bare pieces of copper wire, gauge 18, 32 cm in length

-Two pieces of coated wire with three strands of wire in it, of any thick gauge, around 18 (it does not really matter what you use, as long as it is stiff and insulated). For the purpose of this lab, it will be referred to as heavy-duty house hold wire

-High voltage wire such as NASA specification number SSQ21652 NSFW-SIL-8 wire, silicone insulated, nickel coated copper (made of 1064 strands of #36 wire)

-Two Popsicle sticks

-Aluminum pie plate, preferable with a large bottom area

-String or cable ties

-40mm drain-way tubing (acrylonitrile butadiene styrene)

-52mm drain-way tubing (acrylonitrile butadiene styrene)

- (4) ABS plumbing flanges (acrylonitrile butadiene styrene)

-4 L-brackets (8cm x 2cm)

-4 L-brackets (3.5cm x 4cm)

-Two L-brackets (2.5cm x 1cm)

-Work bench clamp holder (2)

-A stiff piece of cardboard

-Screws (3/4in)

-Waterproof marker (Sharpie)

-screw driver

-hot glue (3 or 4 cylinders of glue)

-hot glue gun

-Masking tape

-High temperature plumbing solder

-Silver led free solder

-Soldering gun

-Wire cutters

-Wire strippers

-Scissors

-string

-meter stick

-Dremel with a circular cutting bit

-Saw

-Mitre box

-Butane torch

-High-temperature tinning flux

-2 alligator clips

-Loctite Xtreme silicon based adhesive

-latex gloves

-Jig-A-Loo lubricant for plastics

 

Procedure:

 

  1. Take one of the Lexan sheets. Cut a piece of string which is 40cm long. Tie the Sharpie to the very end of one side of the string. Make a mark 23cm away from the Sharpie on the string (measure with a ruler, and use the Sharpie to make a little dot).
  2. With the Sharpie, make a mark roughly in the centre of the Lexan sheet. Place the dot on the string on top of the dot on the Lexan sheet, and hold it in place with one’s hand. With the other hand, take the Sharpie, and holding the string taught, move the Sharpie around in a circle. This should give you a perfect circle with a radius of 23 cm.
  3. Go outside, and using the Dremel the circular saw bit, cut along the circumference of the circle drawn on the Lexan sheet.
  4. Repeat steps 1-3 for the second sheet of Lexan. There should now be two perfect circles with a radius of 23cm each. If there is a lot of melted plastic around the edge, cut it off with scissors or anything sharp (such as glass cutters or an exacto knife).
  5. Take the meter stick and the Sharpie. Divide the Lexan disc into 16 equal parts. To do this, place the meter stick so it runs through the middle. Draw a line from one end of the disc to the other, which runs through the center. Rotate the meter stick and draw a line perpendicular to the first. Then draw a line forty-five degrees off in relation to the first (still going through the center), and then twenty-two point five degrees in relation to the first. Do this for both discs
  6. Next a circle must be drawn two centimeters inwards from the circumference of the disc. To do this, repeat the procedure with the string outlined in steps 1-2, except instead of making a mark 23cm away from the Sharpie, make one 21cm away from the Sharpie.
  7. Next holes must be made going through the center of the discs. Repeat the procedure used in steps 1 and 2, but this time make the mark away from the shapie 2.5cm away. This will give a circle with a diameter of 5 cm, which is just big enough to fit the ABS plumbing tubing through.
  8. Go outside and use the Dremel (with the circular saw bit) to cut away the center of the disc, according to the lines just drawn.
  9. Using scissors, cut out the prototype included in this report. Trace it onto a stiff piece of cardboard, and cut out the shape on cardboard. This will serve as a template for the sectors.
  10. Trace the template with a Sharpie onto an aluminum cooking plate. Make sure the areas in which the template is traced are perfectly flat, as if the sector is not perfectly flat it will loose electrons more easily, and will not work as efficiently. Thirty-two sectors are needed for this design (so trace thirty-two outlines on aluminum pie plates).
  11. Take each sector, and copy the marks onto it from the prototype.
  12. Going back to the Lexan discs – they are now divide into sixteen equal parts, and have a circle going around two centimeters in from the circumference of the discs. Place the ruler’s zero mark where this circle intersects with one of the dividing marks. Make a mark with a Sharpie 10cm down from this circle. Repeat this step for each dividing line on both discs.
  13. Place each sector in the proper place and trace around them with a Sharpie. To place them properly, line up the mark in the middle if the sector at the wider side with the spot of intersection of the circle 2cm in from the circumference with the dividing line. The bottom of the sector (or the skinnier end) should be placed so the line marking the middle of the edge is placed over the dividing line. Do this for each sector on each disc.
  14. Use the Loctite Xtreme silicon based adhesive to glue the sectors into their places (which were outlined in step 13). Follow the instructions on the glue’s package.
  15. Take the 52mm drain-way tubing. Cut two pieces of this that are 9cm long. (Cut the plumbing with the saw, and use the miter box to get a ninety-degree clean cut). Jam each of these into a flange, so it comes out the bumpy part. It should be jammed in as far as it goes, and should stick out about 5.5cm.
  16. Take one disc. Place the flat side of the flange on top of the disc (on the side with all the sectors). Position the flange directly over the hole in the disc, so the 40mm drain-way tubing can fit through the hole in the disc and the hole through the flange. Take the hot glue gun and glue the flange to the disc.
  17. Repeat step 16 for the second disc, and second flange.

 

Wooden Frame:

  1. Now the base needs to be built. Take the plank of wood (34cm x 78cm x 2) and place it on a table. This will serve as the base. Two supports must be built. To do this, take the two (6cm x 24.5cm x  3.5cm) pieces of wood. Place each one 20cm inwards length-wise, and 14cm inwards width-wise, with the 3.5cm x 6cm surface of the piece of wood on the base. Trace their outline on the base. Take the L-brackets and screw them into place on the base (using screws and a screwdriver). The (8cm x 2cm) L-brackets are skinnier, and should be screwed to the skinnier 3.5cm width of the wood. The fatter (3.5cm x 4cm) L-brackets should be screwed to the fatter 6cm side of the wood. The supports must be very securely attached to the base. If they can be moved at all (even a little back and forth movement), they need to be better attached – try tightening the screws.
  2. Take the four (15cm x 2cm x 2cm) pieces of wood, and the four (15cm x 4cm x 1.5cm) pieces of wood, and assemble them as shown in the following diagram (with screws, a screwdriver, and the (2.4cm x 1cm) L-brackets.
  3. Using the saw and miter box, cut off two pieces of the 52mm drain-way tubing, 8.5cm long, each. Hot glue this so it is resting in the wooden supports worked on in step 19.
  4. Cut off one more piece of 52mm drain-way tubing, using the saw and miter box. It should be 7mm long.
  5. Slide the 40mm drain-way tubing through the 52mm drain-way tubing on one of the wooden supports. Then slide the two discs onto the 40mm drain-way tubing. The two flat sides of each disc should be facing each other. In between the two discs should be the 7mm long piece of 52mm drain-way tubing. This will keep the plates separated, so they do not rub together. Continue sliding the 40mm tubing, until it goes through the 52mm piece of drain-way tubing on the other wooden support. The discs should now be supported by the wooden support framework.

 

Neutralizers and Collectors:

 

  1. Now the neutralizers must be built. To do this, take the gauge 18 uncoated wire. Cut four pieces, each 66cm long. Bend it into the following shape, so that it fits across the (15cm x 4cm x 1.5cm) piece of wood, and will go under the drain-way tubing shaft.
  2. Take the high voltage NASA copper wire. Strip 24 cm worth of this wire of its insulation (Use wire strippers). Using wire cutters, cut four pieces of stripped wire, 6cm long. Wrap one piece of this wire around the uncoated gauge 18 copper wire four times. It should be able to wrap around four times and still stick off the end of the other wire by two centimeters. Repeat this for each of the four pieces of stripped wire.
  3. Go outside. Take the butane torch and heat up the area where the NASA copper wire is wrapped around the gauge 18 copper wire. Then solder the two pieces together. Do this for each end of the two neutralizers.
  4. Tape the neutralizers to the wooden supports (as shown in the diagram following step 23). The two centimeters of stripped NASA wire should be bent at a ninety degree angle, and should just touch the discs and sectors, but should not exert any pressure upon them.
  5. Take the heavy-duty household wire and cut two pieces 92cm long. Attach them as shown in the following diagram, with staples. Hammer them into place. The heavy-duty household wire should come within 2cm of the discs, but not any closer, and not much further.
  6. Now the collectors must be made. First cut out the prototype for the collectors included in this lab report. Trace this onto an aluminum cooking sheet four times. Cut them out.
  7. Cut two pieces of the NASA wire, each 90cm long.
  8. Take one of these pieces of wire. From one end, strip 2cm of insulator. From the other end, strip 8cm of insulator. Repeat this for both pieces of NASA wire.
  9. Take the 8cm of stripped wire, and split the stands of wire into two equal separate divisions, so the wire makes a “Y”. Do this for both pieces of NASA wire.
  10. Go outside. Take alligator clips and fasten the 8cms of stripped wire to the collector. Coat this with tinning flux (read the instructions on the package to do it properly). Tinning flux helps solder adhere to metal surfaces.
  11. Take the butane torch and heat up the 8cm of stripped wire and the collector.
  12. Solder the 8cm of stripped wire onto the collector. 
  13. Repeat steps 32-34 four times, so each “Y” branch of  high voltage NASA wire is attached to a collector (it should look like the following diagram).
  14. Take a Popsickle stick, and hot glue the collectors and wire as shown in the following diagram. Do this for both high voltage NASA wires. Then the NASA wires leading to the collectors must be glued to the heavy-duty household wire, so that on the outer side of each disc is a collector. Cable ties should be used to help strengthen this positioning. There should be two collectors on either side of the discs (see diagram). Each collector should be roughly 1cm away from a disc.
  15. Take the unconnected ends of the NASA wires. Clip each one to a different workbench clamp holder. Position the wires so that the 2cm of stripped ends are approximately 2cm apart.
  16. Try turning the two discs, by hand, in opposite directions. If no spark is produced, try playing around with parts a little. Moving one wire by even 1cm might fix the problem.  Make sure the neutralizing rods touch their sectors at the same time.
  17. One way to test whether the Wimshurst machine is generating any static electricity is to build an electrophorus (a voltmeter will be useless because voltage produced by the machine is to much for a voltmeter to measure – instead it will say the machine is generating some minute quantity of millivolts). To build an electrophorus, take a cup, needle, scotch tape, and two pieces of aluminum foil (about 2cm x 6cm). Spear the two pieces of aluminum foil with the needle, near the top of the aluminum foil. Tape the needle to the edge of the cup. Touch the needle to one of the end nodes of the Wimshurst machine. If the pieces of aluminum foil fly apart, the machine is generating electricity.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Results:

 

Length of sparks generated: Approximately 2cm

 

sparks3-IMG_3238.jpg

This is a photograph of sparks. One can see the wheel with the sectors spinning in the background.

 

Side view of working Wimsherst machine

 

This is a side view of the Wimshurst machine

 

 

Finished machine (manually driven)

This is a top view of the Wimshurst machine

 

Analysis:

 

            There was a lot of thought that went into the creation of this Wimshurst machine design. To build this machine, there was lots of planning done based on research, although in the end, many refinements were made through trial and error. For example, at least four different designs for neutralizers were experimented with, until one was found to be successful. The following is a list some of the most important materials used, why they were selected, and how they performed.

 

Lexan Polycarbonate Sheets: These were used for discs. They were used for this purpose because they are rigid, light, robust, and most importantly, are insulators. If they were floppy, they would bang together and be wobbling all over, and this would stop the electrical induction from happening, as too many electrons would be lost from the bumps. The discs needed to be light or else they would be too hard to turn, and they would turn slower. This would give electrons time to escape into the air before enough of a charge could build up to make a spark. Has the discs not been robust, they could have broken easily. For example, some internet site will recommend using glass to make the discs. Overall, these discs took a lot of rough treatment, whether it was from dropping them, or even cutting them with the dremel. Lastly, they have to be insulators, so they will not interfere with the electrical induction, and will not steal electrons away from the sectors. The use of Lexan polycarbonate sheets in this design was highly successful, and they have lived up to expectation.

Copper Wire Neutralizers: Wire was used to build the neutralizers. This is because they are bendable, conductive, lightweight, and easy to find. They had to be bendable because there was no other way to put them on, short of bending them around the shaft supporting the discs. The neutralizers had to be highly conductive, in order to convey charges from both sides of the disc to a meeting point as quickly as possible, in order to neutralize them. Technically the neutralizers did not have to been lightweight, but this characteristic made them much easier to attach. They did have to be easy to find, though, since I did not have time for a long search to every electronics surplus store in Montreal in order to find something exotic, which probably also would have been insanely expensive. It took a very long time to come up with a design for the neutralizers, although they are still not perfect. They are flimsy and easy to damage. A big concern is that as the machine runs the wires touching the sectors will start to get bent out of shape, and will stop touching the disc (as happened on many previous designs). This is probably the biggest weakness in this design.

 

Heavy-duty household wire: This was used to support the collectors. It is stiff, but still bendable. This is good because it has to hold up the collectors and support their weight, but it still had to be able to bend around the machine, so it could be attached to the wooden frame. This support could probably be improved on if the machine was being done professionally, but for a “do-it-yourself” project, these are adequate.

 

Aluminum Pie Plates Sectors: The pie plates were cut up into thirty-two sectors. They were choosen because they are thin, durable, and conductive. They are also not coated with a layer of plastic, as many other kinds of metal sheets that were considered for this project were found to be. The sectors had to be conductive because their job is to collect charges. They had to be thin so they would not get scraped off the discs by the neutralizers, and they also had to be durable so they would not get damaged by the conductors.

 

NASA Multistranded Copper Wire: This is used to carry electrons from the collectors to the electrodes at the ends, where the sparks should be made. It has to be able to carry extremely high voltages. This wire worked very well. This job was previously carried out by a smaller wire, with a gauge of 18, and the machine did not work at all until the switch was made.

 

Wooden Framework: The framework has to hold up the discs. It has to be very sturdy, because when the discs spin they shake a lot. If the framework was not sturdy, the machine would fall apart. The framework was made from wood, because wood is an insulator (so it does not disrupt the electrical induction), and also because wood is common and easy to work with. All one needs are some screws and a screwdriver, as opposed to a blow torch or something equally overdramatic and complicated that would need to be used if the framework had been made from plastic or some other material. The wooden framework works very well, and is secure. The only problem with it is that the base is not big enough. If it was a little bigger, it would probably completely stop any shaking/vibrations.

 

Acrylonitrile Butadiene Styrene Drain-way Tubing: This was what was made to build the shaft. It had to be a material with a low friction coefficient. The lower the friction, the easier it is to turn the discs (the importance of which has already been stated). This tubing is very smooth, and works fairly well. It worked a lot better after spraying a lubricant onto it. The machine might work better if an even smoother material was found for the construction of the shafts, but the difference would probably be so small it would not make much of a difference.

 

Conclusion:

 

            The purpose of this project was to build a Wimshurst machine, which was capable of creating high voltage electricity through electrical induction. This was accomplished by the use of polycarbonate sheets for discs, wood for a support framework, plumbing pieces for a shaft to support the discs, aluminum pie plates for sectors, and lots of wires to connect all the pieces together. If these are all properly assembled, when the two discs are turned in opposite directions, the sectors will undergo electrical induction, from which the charges will be collected and directed as electricity in order to make sparks. In this project, the Wimshurst machine was able to make electricity and sparks. This means the hypothesis was correct.

 

 An interesting observation resulting from this project was that not only was a voltmeter not able to give a reading on how many volts were being produced by the machine, but also that when using a gauge 18 wire, the Wimshurst machine would not work. An even thicker wire had to be used. This was due to the unusually high voltage produced by the Wimshurst machine. There were many problems that occurred during the making of this machine. All the problems were over come by using different materials, or by sitting back and thinking on what could be causing the problems. Many laws of physics are involved in making this machine run, such as electric charges, electric fields, electrical induction, conductivity, etc. This is one of the reasons the Wimshurst machine has been around for centuries, and is still used to study and teach about electricity.

 

It was found that for the purposes of this project, the best way of measuring the voltage was actually an electrophorus. As the voltage increases, the two pieces of aluminum foil fly further and further apart. They will work no matter what the voltage, which is very important, since that is something the voltmeter will not do. The electrophorus is a sure fire way of being able to tell whether the machine is producing electricity (incase it is not generating sparks).

 

            Even though the Wimhurst machine made in the project works, there are many improvements that could be added. For starters, a better support could be used to hold up the collectors – something more professional and sturdy than wire. Also, if the wheels were lighter it would make the machine run more smoothly. The biggest improvement of all would be to make the entire machine very sturdy, and secure everything in a position that would ensure the success of the machine. As it is now, there is always something that falls out of place, or needs to be tinkered with before a spark can be produced. Many more adjustment should be made to the Wimshurst machine design explained in this lab.


Natasha Dudek

St.Georges High School

Science Fair 2006-2007

 

 

 

 

 

 

 

 

 

How Terminal Electrode Diameter Influences the Size of the Maximum Sparks Created With a Wimshurst Machine

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Purpose: To determine whether there is a relation between the radius of the terminal electrodes of a Wimshurst machine, and the maximum length of the sparks achievable by the Wimshurst machine.

 

Hypothesis: If different sized terminal electrodes attached to the end of the wire leading from the collectors, then the maximum length of the sparks will change, depending on the radius of the terminal electrode.

 

Materials:

-Wimshurst machine with no permanent terminal electrodes attached to the wire leading from the collectors. Instead the terminal electrode should be 2cm of stripped wire.

-Two spherical curtain rod ends of different sizes

-Two people

-Ruler

-Masking tape

 

Procedure:

  1. Make sure the Wimshurst machine is properly set up. Have the terminal electrodes bare (just 2cm of stripped wire).
  2. Dim the lights
  3. Have somebody spin the discs of the Wimshurst machine
  4. As the other person spins the discs in opposite directions, put the two terminal electrodes so they are touching. Slowly pull them apart, until no more sparks are being made. Even if no immediate sparks are produced, keep the discs spinning for one minute to make sure none are building up. As soon as that point is reached, leave them where they are, tell the person spinning the discs to stop, and turn on the lights.
  5. Record the distance from one tip of the electrode to the other.
  6. Repeat steps 2-5 for each different terminal electrode.
  7. Repeat the entire experiment (steps 2-6) twice, so three data points are collected for every diameter of terminal electrode.

*To attach the terminal electrodes, there will be a little groove around the backside of the curtain rod end. Gently insert the stripped wire into the groove. Use masking tape to tape the end of the ball to the wire, so it keeps the connection.

 

Results:

                                                            Maximum Length of Sparks (mm)

Diameter of Terminal Electrode (mm)

Trial 1

Trial 2

Trial 3

0.16

1

2

1

3

13

15

14

4.5

25

24

25

 

 

  

Diameter of Terminal Electrode (mm)

Average Max. Length of Spark (mm)

0.16

1.3

3

14

4.5

24.6

 

 

 

                       

 

 

Regression Line: y = ax² + bx + c

            Where y= 0.60x² + 2.58x + 0.87

                        R²=1

 

 

Conclusion:

 

      This lab indicates that there is a relation between the diameter of the terminal electrode on a Wimshurst machine and the maximum size of the sparks that can be produced. In the experiment, three different size terminal electrodes were attached to the end of the wire leading from the collectors. Each one was slowly moved further and further apart (while connected), until it reached a point where no more sparks were being produced. Upon reaching that point, the experiment was stopped, and the distance between the tips of the two terminal electrodes was measured and recorded. From the data points collected, it would seem that there is a quadratic relationship between the diameter of the terminal electrode and the maximum length of the sparks it can produce. There was a correlation of 1 between these variables, which means a perfect fit. It can therefore be assumed that to build the best Wimshurst machine possible, one should make the diameter of the terminal electrodes as large as possible, to maximize the length of the sparks. Sources of error include having electrons lost due to the corona effect, and not having an accurate enough measurement system. The curtain ends also have some kind of plastic coating which insulates it and decreases the size of the sparks created, although since all both the curtain ends had this coating, it decreases the affect of this source of error since it was relative. Three improvements that could be made to this experiment would be having more data points collected, having more sizes of terminal electrodes to test, and having a better way of attaching the terminal electrodes to the end of the wire which leads from the collectors.