Problems Building a Van De Graaff Generator

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Discussion Overview

The discussion revolves around the challenges faced in building a small Van de Graaff generator, focusing on design choices, material selection, and performance issues. Participants explore various aspects of the generator's construction, including the effectiveness of different components and configurations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes their construction process, including the use of 3D printed PLA for the body, PVC for the rollers, and various materials for the belt and metal domes.
  • Another participant questions whether the top pulley shaft uses a bushing or bearing and suggests considering a vacuum cleaner drive belt as an alternative to the rubber band.
  • A different participant emphasizes the importance of having a metal sphere for the top and mentions that the rollers should be made of different materials according to the electrostatic series.
  • Concerns are raised about the insulating properties of the column material, which may affect charge retention, and the need for a contact potential difference between the pulleys.
  • One participant notes that a smooth and clean surface is crucial for performance and suggests drying components to improve effectiveness.

Areas of Agreement / Disagreement

Participants express various ideas and suggestions, but there is no consensus on the best approach or solution to the issues raised. Multiple competing views on materials and configurations remain present throughout the discussion.

Contextual Notes

Participants mention the importance of different materials for the rollers and the potential impact of surface conditions on performance. There are also references to specific measurements and performance metrics, but no detailed mathematical analysis is provided.

Who May Find This Useful

This discussion may be useful for hobbyists and students interested in building electrostatic generators, as well as those exploring the principles of electrostatics and materials science.

AniV
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I have been trying to build a small Van de Graaff generator based on the designs found here: http://rimstar.org/equip/build_make_van_de_graaff.htm

Unfortunately I haven't been having much luck. How can I improve it?
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13692923_587926388052702_8808151424123490542_o.jpg

The body was 3D printed using PLA plastic.
It encloses the rubber band belt completely.
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13735540_587926381386036_2540663988244643720_o.jpg

The bottom motorized roller is made PCV electrical tape and a slice of PVC tubing:
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13698065_587926361386038_7472904692042366737_o.jpg

The top roller is made of nylon thread:
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13680297_587926378052703_6114147970296557842_o.jpg

The rubber band is one of those used to hold together vegetables from the supermarket.
The configuration is shows below.

https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13723871_587926374719370_906130344536881567_o.jpg


I have used many combinations of many materials for each part. I have tried using steel drinking cups and silver cups for the metal domes. I have tired thick, and thin rubber bands fro the belt, as well as balloon rubber for the belt. I also tried multiple materials for the motorized roller, including only teflon tape, only PCV electrical tape, and the current design with the PCV piping.

The generator does work, as I have measured potential differences between the two cups using a multimeter, but it doesn't create arcs. Do I need to insulate the metal better?
 
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Likes   Reactions: 1oldman2
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Is the top pulley shaft riding on some sort of bushing or bearing? Would/could a vacuum cleaner drive belt be used in place of the rubber band? I'm not sure what the brush/pickup consists of but that might be crucial to generating more power, These are just thoughts that initially crossed my mind, I imagine someone with more knowledge will be giving an opinion before long. As an afterthought this might have been better placed in "electrical engineering" thread, I'm curious to see how this works out. Something along the lines of a flag pole cap ball might be the shortest route to your dome problem.
 
AniV said:
I have been trying to build a small Van de Graaff generator based on the designs found here: http://rimstar.org/equip/build_make_van_de_graaff.htm

Unfortunately I haven't been having much luck. How can I improve it?
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13692923_587926388052702_8808151424123490542_o.jpg

The body was 3D printed using PLA plastic.
It encloses the rubber band belt completely.
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13735540_587926381386036_2540663988244643720_o.jpg

The bottom motorized roller is made PCV electrical tape and a slice of PVC tubing:
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13698065_587926361386038_7472904692042366737_o.jpg

The top roller is made of nylon thread:
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13680297_587926378052703_6114147970296557842_o.jpg

The rubber band is one of those used to hold together vegetables from the supermarket.
The configuration is shows below.

https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13723871_587926374719370_906130344536881567_o.jpgI have used many combinations of many materials for each part. I have tried using steel drinking cups and silver cups for the metal domes. I have tired thick, and thin rubber bands fro the belt, as well as balloon rubber for the belt. I also tried multiple materials for the motorized roller, including only teflon tape, only PCV electrical tape, and the current design with the PCV piping.

The generator does work, as I have measured potential differences between the two cups using a multimeter, but it doesn't create arcs. Do I need to insulate the metal better?
Do you have a metal sphere for the top. This seems important. The machine I use has a metal top roller and also some thin metal pick up brushes. I think the two rollers must be different material according to the electro static series. My roller is inside the top sphere.
With a commercial machine I find it is very important that there is a perfect smooth and clean surface everywhere, and I dry everything with a hair dryer. It is also possible the belt is leaky.
 
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Likes   Reactions: 1oldman2
What is that material for the column? It has to be a really good non-conductor or all your charge will bleed away. For the design you show there has to be a contact potential difference between the belt-lower pulley and the belt-upper pulley. Since the material is the same for the belt the pulleys must be made of different materials. The cheep one of these I bought generates ~100 uA of current which one may measure with an multimeter.
 

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