# Van de Graaf generator - Why won't it work? **URL:** \ **Category:** Factual Questions\ **Created:** [July 24, 2013, 1:22am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342 "2013-07-24T01:22:13Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![blood63](https://avatars.discourse-cdn.com/v4/letter/b/97f17d/32.png) [@blood63](https://boards.straightdope.com/u/blood63)\ **Post date:** [July 24, 2013, 1:22am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/1 "2013-07-24T01:22:13Z")
I built a Van de Graaf generator using a plan from Instructables with a few modifications. I’m using two bed rollers, one covered in aluminum tape and the other with teflon tape. The rollers are 16 inches apart. I used an old bike inner tube as my belt. Its about two inches wide so it can carry a lot of electrons. My brushes are made of fine copper bristles that rub smoothly against the belt at both the bottom and top rollers. Oh, and I didn’t forget to ground the bottom brush. The whole thing looks great and moves very smoothly but I don’t get any charge build up. I am a teacher and have used Van de Graaf generators for years. I know they can be very fussy. Any advice? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 24, 2013, 1:31am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/2 "2013-07-24T01:31:12Z")
You do have a dome at the top for accumulating charge, right? I know it sounds obvious, but you didn’t mention it. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [July 24, 2013, 2:09am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/3 "2013-07-24T02:09:21Z")
There are several Van de Graff generators on Instructables. Which one did you base yours on, and what changes did you make? ---
**Author:** ![nearwildheaven](https://avatars.discourse-cdn.com/v4/letter/n/90db22/32.png) [@nearwildheaven](https://boards.straightdope.com/u/nearwildheaven)\ **Post date:** [July 24, 2013, 2:15am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/4 "2013-07-24T02:15:58Z")
When I saw the thread title, I was thinking that this thread belonged in Cafe Society. > **[Van der Graaf Generator](https://en.wikipedia.org/wiki/Van_der_Graaf_Generator)** > > Van der Graaf Generator are an English progressive rock band, formed in 1967 in Manchester by singer-songwriters Peter Hammill and Chris Judge Smith and the first act signed by Charisma Records. They did not experience much commercial success in the UK, but became popular in Italy during the 1970s. In 2005 the band reformed, and are still musically active with a line-up of Hammill, organist Hugh Banton and drummer Guy Evans. > The band formed at the University of Manchester, but settled in Lond... ---
**Author:** ![blood63](https://avatars.discourse-cdn.com/v4/letter/b/97f17d/32.png) [@blood63](https://boards.straightdope.com/u/blood63)\ **Post date:** [July 24, 2013, 2:19am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/5 "2013-07-24T02:19:50Z")
> [@scr4](#): > > There are several Van de Graff generators on Instructables. Which one did you base yours on, and what changes did you make? [http://www.instructables.com/id/350kv-Van-de-Graaff-Generator/](http://www.instructables.com/id/350kv-Van-de-Graaff-Generator/) I tried making the pin brushes that are suggested here but my experience is with wire brushes so I went with that. I used 3" ABS instead of PVC. I made my own belt instead of buying one. I have not connected it to a permanent motor just yet. I am using my drill to turn the belt. I used two aluminum bowls for a dome. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [July 24, 2013, 2:24am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/6 "2013-07-24T02:24:46Z")
the bike inner tube may not be good rubber for this. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 24, 2013, 2:25am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/7 "2013-07-24T02:25:14Z")
The bike inner tube may be too conductive - too much carbon black in the rubber. ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [July 24, 2013, 2:37am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/8 "2013-07-24T02:37:48Z")
My first thought was that the inner tube might not be ideal as well. Maybe get a [latex exercise band](http://www.amazon.com/Thera-band-20560-Single-Exercise-Special/dp/B000FGZ1TE) and glue it into a loop. ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [July 24, 2013, 2:45am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/9 "2013-07-24T02:45:03Z")
Too late for ETA. Maybe an easily overlooked error. Is one of the brushes touching the belt? ---
**Author:** ![blood63](https://avatars.discourse-cdn.com/v4/letter/b/97f17d/32.png) [@blood63](https://boards.straightdope.com/u/blood63)\ **Post date:** [July 24, 2013, 3:13am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/10 "2013-07-24T03:13:16Z")
> [@Projammer](#): > > Too late for ETA. Maybe an easily overlooked error. Is one of the brushes touching the belt? both brushes are touching the belt. ---
**Author:** ![california\_jobcase](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@california\_jobcase](https://boards.straightdope.com/u/california_jobcase)\ **Post date:** [July 24, 2013, 3:34am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/11 "2013-07-24T03:34:27Z")
I used Winsco brand Van De Graaffs for years. The belt installation instructions always showed that the brushes should be as near as possible to the belt without touching it. Also, to what have you grounded the bottom brush? On commercial models, it’s attached to the bottom casing. The casing is isolated from the motor and its wiring. ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [July 24, 2013, 3:35am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/12 "2013-07-24T03:35:40Z")
From your link, page 3, making the brushes. > [@](#): > > What’s important to keep in mind, is that the more pointy the ends on the brush the better, and that the brushes do not actually touch the belt. It is best to keep each about 1/8 of an inch away from the belt. The devil is in the details. 😉 ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [July 24, 2013, 3:54am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/13 "2013-07-24T03:54:36Z")
Another too late for ETA: 🙂 What about using [metal nit combs](http://www.amazon.com/Heavy-Weight-Tooth-Metal-Comb/dp/B003UBE2A0) for brushes? Pointy and even. ---
**Author:** ![blood63](https://avatars.discourse-cdn.com/v4/letter/b/97f17d/32.png) [@blood63](https://boards.straightdope.com/u/blood63)\ **Post date:** [July 24, 2013, 1:40pm UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/14 "2013-07-24T13:40:17Z")
> [@Projammer](#): > > From your link, page 3, making the brushes. > > The devil is in the details. 😉 I have a working model from school (I am a teacher). It’s a smaller version. My goal is to make one much larger. In the smaller version, the brushes do touch the belt and it doesn’t work when the don’t. That is a detail that I have spent a lot of time with. I have spent hours making different types of brushes. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [July 24, 2013, 3:32pm UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/15 "2013-07-24T15:32:45Z")
Did you remember to use the special evil laugh?😛 ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [July 24, 2013, 4:10pm UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/16 "2013-07-24T16:10:26Z")
> [@blood63](#): > > I have a working model from school (I am a teacher). It’s a smaller version. My goal is to make one much larger. In the smaller version, the brushes do touch the belt and it doesn’t work when the don’t. That is a detail that I have spent a lot of time with. I have spent hours making different types of brushes. What was the belt made from in that version? ---
**Author:** ![blood63](https://avatars.discourse-cdn.com/v4/letter/b/97f17d/32.png) [@blood63](https://boards.straightdope.com/u/blood63)\ **Post date:** [July 25, 2013, 12:39am UTC](https://boards.straightdope.com/t/van-de-graaf-generator-why-wont-it-work/664342/17 "2013-07-25T00:39:20Z")
> [@TriPolar](#): > > What was the belt made from in that version? That belt was made from rubber but I’m learning that there are different kinds of rubber. Tire rubber might not be the best. I have just tried silk but it has no flexibility so it is hard to get the belt the exact right length. What I really need is neoprene rubber.