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Incorporated, a worldwide network of science museums and related institutions.
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Jesse,

I have worked a lot with VanDeGraff generators myself.  Not only can
they be tricky to maintain, but It can be difficult to find good ones
on the market.  If you can get a good one, then there are three simple
things I recommend to keep them in top condition:

1) Wipe down components regularly with alcohol (I use methanol).  As
Dave already mentioned, water is death and dust is every bit as bad.
Make sure you clean off all the charge pick-ups (top and bottom), the
rollers and bearings, the belt, and the INSIDE OF THE COLUMN.  Be
liberal with the Alcohol, make sure you use a lint free cloth, and when
the alcohol evaporates and you have a clean, dry machine.

2) Make sure you have a good belt.  If the belt starts to shred, little
bits come off and once you have belt-bits inside the column, you lose
charge.  Be careful your contacts are as close to the belt as possible,
but don't actually touch, this will quickly scrape and ruin your charge
carrier.

3) Make a discharge wand.  A piece of aluminum rod 1/4 inch in diameter
(or close), rounded at one end, and on the other end, the last inch
should be tapered to a rounded point.  This simple device will not only
keep greasy and dirty hands off of the top terminal (which contributes
to dirt pick-up and charge loss), but if your VanDegraff subject
decides to let go of the machine while it's running, they won't feel a
shock, try it, it's amazing.  Richard Ford showed me this little trick
while I was at the U of I in Urbana, IL.  As long as you are standing
on a stool, you can touch it and let go as you want, and there's no
problem.  This also lets the person reach down and touch the bottom of
the generator to discharge without feeling a shock (it distributes the
charge movement over more of your hand instead of through one spot).

Personally, I LOVED the VanDeGraaf from Science First, but ever since
they put the big square, pointy metal base on the bottom, it just
doesn't work as well.  If they will sell it to you, you can buy half of
a top terminal, turn it upside down, put all the components onto a
wooden base and slide the half-terminal down to cover it up.  It looks
classy, and it has rounded edges.  No switch, but who cares, get a foot
pedal.  I'd be happy to discuss the mods with you off-list if you like.
  Once you get one of these working, all you have to do is keep it clean
and it should give you years of good service.


***If anyone else knows of any other good VDG generators out there, I'd
love to hear about it.

I hope this helps!

Matthew Wenger
University of Arizona
Flandrau Science Center
Tucson, AZ


On Feb 17, 2004, at 6:31 AM, Beryl Rosenthal wrote:

> ISEN-ASTC-L is a service of the Association of Science-Technology
> Centers
> Incorporated, a worldwide network of science museums and related
> institutions.
> ***********************************************************************
> ******
>
> I particularly agree with the moisture comment.  We have done a demo
> with rice krispies exploding all over the place once the charge has
> been built up (it makes our curators crazy!), and it ONLY works
> correctly if the cereal has been dried out for several days prior to
> the demo.
> Beryl
>
>> ISEN-ASTC-L is a service of the Association of Science-Technology
>> Centers
>> Incorporated, a worldwide network of science museums and related
>> institutions.
>> **********************************************************************
>> *******
>>
>> Unpredictability is part of the nature of Van de Graff's.
>>
>> It doesn't take much for them to stop working or to
>> perform really poorly.  Two things are particularly bad
>> for building a charge... any moisture in the air and the
>> charge will bleed off into the air very quickly... and any
>> tarnish or dirt on the ball and it won't hold a charge.
>>
>> Depending on what your ball is made of (probably
>> spun aluminum) you could try cleaning it with an
>> alcohol pad (inside and out) before you run it.  Clean
>> the belt too...
>>
>> Good luck...
>>
>> Dave Taylor
>> ------------------------------
>>
>>>  From: Jesse Alexander <[log in to unmask]>
>>>  Reply-To: Informal Science Education Network
>>>  Date: Sat, 14 Feb 2004 02:56:24 -0800
>>>  To: [log in to unmask]
>>>  Subject: VDG Questions
>>
>>>  Hey Folks,
>>>
>>>  I'm looking for inexpensive ("pre-owned" is ok) Van de
>>>  Graaff generators that can be easily taken on the road
>>>  during traveling science programs. I am also looking
>>>  for "care and feeding" guides for VDGs.
>>>
>>>  The generator should be about 24" tall so that it can
>>>  be easily seen during assemblies of 300+ kids.
>>>
>>>  We have had a lot of problems with "unpredictable" VDG
>>>  behavior on the road. Something seems to be shorting
>>>  out the globe. I can develop a charge by holding my
>>>  fingers about a 1/4" from the belt, but the charge
>>>  somehow doesn't make it to the globe (once I remove my
>>>  fingers-of course). The rubber belt is exposed on our
>>>  Pasco SF-9722 VDG.
>>>
>>>  Any ideas?
>>>  Jesse Alexander, WB2IFS
>>>  Science Evangalist/Demonstrator
>>>  Liberty Science Center
>>
>> **********************************************************************
>> *
>> More information about the Informal Science Education Network and the
>> Association of Science-Technology Centers may be found at
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>> To remove your e-mail address from the ISEN-ASTC-L list, send the
>> message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
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>
>
> --
> Beryl Rosenthal, Ph.D.
> Director of Exhibitions and Public Programs
> MIT Museum
> 265 Massachusetts Ave.
> Cambridge, MA  02139
> Tel: 617-452-2111
> Fax: 617-253-8994
> [log in to unmask]
>
> ***********************************************************************
> More information about the Informal Science Education Network and the
> Association of Science-Technology Centers may be found at
> http://www.astc.org.
> To remove your e-mail address from the ISEN-ASTC-L list, send the
> message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
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>

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