Vol. 17: The Wimshurst Influence Machine

When assembling a proper laboratory, the gentleman or lady experimenter should be sure to include a Wimshurst electrostatic generating machine.

By Jake von Slatt

Photos by Jake von Slatt

Illustrations by Damien Scogin

+ Downloads & Extras:

Wimshurst Inflluence Machine:
Building Franklin's Bells
By Jake von Slatt

Intro:
One popular demonstration of electrostatic charge is known as Franklin's Bells. Franklin's Bells are just that, a pair of metal bells, mounted on insulating supports, with a wooden or pith ball suspended from a thread between them. When the bells are connected to a source of electrical charge such as a Wimshurst influence machine, the wooden ball is attracted to one of the bells. When the ball strikes the bell, it acquires a like charge from the bell, and is then repelled, swinging to the other bell, where the process is repeated, resulting in a prolonged ding-ding-ding-ding for as long as the charge persists.

Now, ol' Ben Franklin did not have a Wimshurst machine - they were invented about 100 years after he performed his experiments. What Franklin did was connect one of the bells to a lightning rod on top of his house and the other to ground - extremely dangerous! - so that when an electrical storm moved into the area, the bells would ring and alert him to gather his kite flying gear!

The above set of Franklin's Bells was made from a simple wooden base, 3 sections of 3/8" fiberglass rod, and 2 brass bells from an old desktop telephone. The "clapper" is a wooden bead strung on a length of upholstery thread, attached by a clothespin.

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Showing messages 1 through 12 of 12.

Unable to access parts diagram
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Dear Jason,

Thank you for your excellent article on making a Wimshurst machine! One small problem...I get an "Access forbidden" error when trying to reach the parts diagram at http://cdn.makezine.com/make/17/wimshurst_diagram.jpg

Is there some other place where I can reach this diagram?
Thank you very much!

Posted by LouisTF on October 03, 2009 at 19:50:18 Pacific Time

Unable to access parts diagram
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Hi LouisTF,

The link is working fine for me. If you look under links above and right-click on "Wimshurst Generator dimension diagram of the main parts" you can save it on your computer.

Cheers,
Goli

Posted by golim on October 05, 2009 at 12:08:56 Pacific Time

whimhurst machine rubber washers
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I'm confused about the rubber washers (2) and where they go. Step 11 pictures what I think are the rubber washers 3/8"?(1 for each), but wouldn't that be an insulator?.

Kimberly
Posted by looking up on July 12, 2009 at 08:53:52 Pacific Time

whimhurst machine rubber washers
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The rubber washers are just to provide some spring to keep the combs in place, only one washer is used on each comb support.
Posted by vonSlatt on July 12, 2009 at 10:10:33 Pacific Time

Tube size
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Jake,

What size is the fluorencent tube holders? Are they for T12 or T8?

Mark

Posted by ScienceDesign on May 14, 2009 at 12:49:03 Pacific Time

Tube size
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I think T12 - the larger one.
Posted by vonSlatt on May 14, 2009 at 12:58:10 Pacific Time

Wimshurst Parts List
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Jake,

I'm buying the parts for the Influence Machine. Some of the parts are harder to get than others.
The brazing rods, McMaster doesn't have it, but they have brass rods 1/8", does the type of brass matter?
Part (M) the 1" copper hangers, what's 1", not the width, the picture doesn't seem to show that?

Mark
Posted by ScienceDesign on May 13, 2009 at 19:25:39 Pacific Time

Wimshurst Parts List
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1/8 brass rod is just fine ! The brazing rod is really cheap though.
Posted by vonSlatt on May 14, 2009 at 12:59:19 Pacific Time

Whimshurst machine details
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I'm confused about the Wimshurst machine instructions. Materials list in MAKE magazine shows [E]3/8" OD thin wall brass tubing, 3' section, then later, in the [NOT SHOWN]section it calls for 3/8" OD thin wall brass tubing, 6" lengths (2). I've been pouring over the instructions steps & see a vague reference to a brass tube, no indication of length, in step 17b. Where exactly am I using a total of 4' of brass tubing? I am just plain missing it, or it's not there. Can anyone help me out, here? Thanks. -Paul
Posted by pvgray on March 10, 2009 at 11:17:42 Pacific Time

Whimshurst machine details
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Hi Paul,

The tubing is sold in 4' lengths, but you'll only need (2) 6" sections.

Cheers,

Jake.
Posted by vonSlatt on May 04, 2009 at 15:11:16 Pacific Time

Whimshurst machine details
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er, meant 3' lengths!
Posted by vonSlatt on May 04, 2009 at 15:11:52 Pacific Time

Whimshurst machine details
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Hello, McMaster-Carr now sells brass tubing in one foot lengths, but with four wall thicknesses; .014",.032",.049",.065". Which is the best wall thickness? Thank you, Michael J.

Posted by Cherokeemike on March 03, 2010 at 13:54:40 Pacific Time

Showing messages 1 through 12 of 12.

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