I built this Whimshurst generator awhile back and I didn't take pictures through the build. But I thought I could share a few ideas to help others in a similar project of their own. I can through a nasty spark approx 2" on a dry winter day using the Leyden jars and has some cool demos I'll discuss later.
First some great resources are:
1. http://www.coe.ufrj.br/~acmq/electrostatic.html
2. The Boy Electrician - by Alfred P Morgan
3. Homemade Lightening - by R.A. Ford
"The Boy Eectrician" is a collection of a number of projects if you haven't already heard of it - get it. Also "The Boy Mechanic - Vols 1, 2 & 3" are worth every penny for great project ideas. But back to the whimshurst...
Parts List Consists of:
a. Leyden jars - Spaghetti containers from the dollar store. I tossed the plastic caps and turned cherry lids on a lathe and used rubber bands from a roller conveyor to function as a gasket.
b. The lucite rods (3/4" diam) and the plexiglass disks (1/4" think) came from a local plastics supplier.
c. The brass fittings include drawer pulls of solid brass, solid brass rod from hobby store (K&S brand), and misc brass screws and inserts. NOTE: The drawer pulls are lacquered and need to have it removed for electrical continuity. Use a propane torch to burn it off and then scrub them with steel wool.
d. The sectors on the disk are aluminum flashing.
e. The grounding brushes are braided copper wire used for hobby racing slot cars.
f. The belt drives are rubber bands taken from a roller conveyor - these are really grippy and can be tightened up by cutting then melting them back together as they stretch.
First some great resources are:
1. http://www.coe.ufrj.br/~acmq/electrostatic.html
2. The Boy Electrician - by Alfred P Morgan
3. Homemade Lightening - by R.A. Ford
"The Boy Eectrician" is a collection of a number of projects if you haven't already heard of it - get it. Also "The Boy Mechanic - Vols 1, 2 & 3" are worth every penny for great project ideas. But back to the whimshurst...
Parts List Consists of:
a. Leyden jars - Spaghetti containers from the dollar store. I tossed the plastic caps and turned cherry lids on a lathe and used rubber bands from a roller conveyor to function as a gasket.
b. The lucite rods (3/4" diam) and the plexiglass disks (1/4" think) came from a local plastics supplier.
c. The brass fittings include drawer pulls of solid brass, solid brass rod from hobby store (K&S brand), and misc brass screws and inserts. NOTE: The drawer pulls are lacquered and need to have it removed for electrical continuity. Use a propane torch to burn it off and then scrub them with steel wool.
d. The sectors on the disk are aluminum flashing.
e. The grounding brushes are braided copper wire used for hobby racing slot cars.
f. The belt drives are rubber bands taken from a roller conveyor - these are really grippy and can be tightened up by cutting then melting them back together as they stretch.
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The Disks:
Cut the disks as pairs and sand them as perfectly as possible so they rotate smoothly. I cut mine at 18" diameter. It makes a sizeable whimshurst and decent sized sparks. The edges are sanded then polished with fine steel wool.
Layout a scaled sketch of how the sectors will be epoxied onto the disks. The sectors must be an even number and exactly opposite of each other. Sand the surfaces of the sectors so they adhere well to the plexiglass and the exterior surface is very conductive ( no coatings anywhere is a very important theme her to make this work).
The Hubs:
The hubs were turned in a lathe from solid cherry glued up in blocks. I then end bored a 1/2" hole in the center for the brass tube bushing to eventually be inserted and epoxied in each hub. I turned one piece first twice as long as one hub, then cut it in half on a bandsaw so I could ensure equal diameters as possible to make two hubs. The disks each have a notch for which the belt rides in it. The notch depth is not critical to be exact to the other but use a caliper anyway. The disks just need to spin in opposite directions. The hubs ride on an aluminum 1/2" solid shaft (K&S hobby) with NO grease or lube of any kind. I didn't want to risk contaminating any parts with something conductive then try to clean it off. The brass tube sleeve bushing on the aluminum is plenty slick for the low rpms such that a lube is not needed. A screw insert is located at the very top of the vertical shaft supports on each support to keep the shaft from spining with the disks and drilling into the support.
The Pick Up Combs:
You will need to drill a series of 1/16" holes through a brass rod (~ 3/16" diam) in a straight line that is approximately as long as the sector on the disk. To do this precisely as possible, cut a v-block out of a piece of scrap wood to nest the 3/16" rod in it so you can use it as a holder for a drill press to drill the holes. Evenly space the holes (aprox every 1/4") by marking each location by a small notch cut in it with a file. Once all the holes are drilled for BOTH ends of the rod, bend the rod around a piece of pipe to make a tuning fork type of shape.
Make the pick up pins with 1/16" brass stock and solder them into each hole. Then solder in the end extension rod at the base of the tuning fork shape.
Cut the disks as pairs and sand them as perfectly as possible so they rotate smoothly. I cut mine at 18" diameter. It makes a sizeable whimshurst and decent sized sparks. The edges are sanded then polished with fine steel wool.
Layout a scaled sketch of how the sectors will be epoxied onto the disks. The sectors must be an even number and exactly opposite of each other. Sand the surfaces of the sectors so they adhere well to the plexiglass and the exterior surface is very conductive ( no coatings anywhere is a very important theme her to make this work).
The Hubs:
The hubs were turned in a lathe from solid cherry glued up in blocks. I then end bored a 1/2" hole in the center for the brass tube bushing to eventually be inserted and epoxied in each hub. I turned one piece first twice as long as one hub, then cut it in half on a bandsaw so I could ensure equal diameters as possible to make two hubs. The disks each have a notch for which the belt rides in it. The notch depth is not critical to be exact to the other but use a caliper anyway. The disks just need to spin in opposite directions. The hubs ride on an aluminum 1/2" solid shaft (K&S hobby) with NO grease or lube of any kind. I didn't want to risk contaminating any parts with something conductive then try to clean it off. The brass tube sleeve bushing on the aluminum is plenty slick for the low rpms such that a lube is not needed. A screw insert is located at the very top of the vertical shaft supports on each support to keep the shaft from spining with the disks and drilling into the support.
The Pick Up Combs:
You will need to drill a series of 1/16" holes through a brass rod (~ 3/16" diam) in a straight line that is approximately as long as the sector on the disk. To do this precisely as possible, cut a v-block out of a piece of scrap wood to nest the 3/16" rod in it so you can use it as a holder for a drill press to drill the holes. Evenly space the holes (aprox every 1/4") by marking each location by a small notch cut in it with a file. Once all the holes are drilled for BOTH ends of the rod, bend the rod around a piece of pipe to make a tuning fork type of shape.
Make the pick up pins with 1/16" brass stock and solder them into each hole. Then solder in the end extension rod at the base of the tuning fork shape.
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When I was a boy, in the jurassic, I was able to restore a Whimshurst machine belonging to the school where I studied. It had both discs warped, I could straighten them partially. At that time there were not as many materials as now.