SpudFiles

I'm going to be making a pretty decent sized van de graff generator and I just had a few questions about them before I start. If anyone knows is the wire/brush supposed to touch the belt or are they just supposed to be close the it? I'm going to have one of the rollers just be 1.5" pvc and one of them be wrapped in tin foil. Are these good materials to use? And I was thinking about using nylon panty hose as the belt for the rollers. Does anyone that has made one before have any advice to make mine better?

I love Van DeGraaf generators...

1) The brushes do NOT touch. This will ruin your belt. Have them hovering about 1/8 above the belt. Any closer and there is a chance of the vibrations from the motor bouncing the brushes onto the belt and ruining it. The closer it is, the more effective, but be prepared togo through quite a few belts

2) For your belt, I would suggest surgical tubing, If you can find it (Make sure that the tubing is yellowish, not black. The black kind contains carbon and will ruin your charge)

3) I wouldn't suggest using aluminum foil, it tends to flake off and ruin your charge. After it has flaked, it's a bitch to clean out of the whole thing.

4) Go to google and type in "triboelectric series" (You can't really blame me for having to stop and remember what that is ). This will give you a chart with the charges of quite a few materials. Put one with a positive charge on one end, and one with a negative charge on the other. Also, try to stay away from materials that flake or make dust, as they tend to ruin any charge you have.

My favorite site comes through again...
1) This is for plans for the generator itself.
http://www.howstuffworks.com/vdg3.htm

2) This is for the "triboelectric series"
http://www.howstuffworks.com/vdg1.htm

This wiki looks pretty good. http://en.wikipedia.org/wiki/Image:Van_ ... erator.svg

I've made a couple minis and one pretty decent sized one. The wire/brush should be VERY close to (but not touching) the discharge roller and the ground roller. PVC is an excellent insulator, so thats a good idea, but I'd definately use a rubber belt instead of pantyhose.. My big one uses a flat automotive belt and it works quite well. If you do use an automotive belt, make sure it is JUST rubber and it doesn't have any reinforcing bands. ( These are sometimes made of metal wire. Metal=NO NO!) If you run into any trouble, PM me.

Hmm well instead of tin foil maybe I'll use copper or something. Does it matter if the conductor and the insulator rollers are switched? Like in the wiki the metal one is on the bottom is it ok to switch that? And can I use different size rollers? Because I dont want to have to find 1.5" copper tube.

I think that the howstuffworks.com links should take care of 99% of the questions that you have. You're welcome !

Oh yeah, I would suggest "crowning" the rollers. This helps to keep the belt on track. Crowing is when the middle is wider than the two ends. Think of an old wooden barrel, how the middle is wider. That's crowned.

(Slightly off-topic)
Has anyone ever done a wimshurst generator before? I have an unfinished one sitting on my porch which I hope to finish when summer comes around (Its too big to store inside; the plates are 2' in diameter).
Ill post a picture of it later.

No, don't swith the conducting and insulating rollers. You can use different sized rollers, but it won't be as efficient at generating the high voltage.

_Fnord, that's a HUGE Wimshurst generator! The one I built had like 8" dia. plates!
BTW tesla coils are SOO much better than any electrostatic generator! Build one! I've had hours and hours of fun with mine...

Ok do you think it would be ok to get some glass tube from a flourescent bulb or something and then glue that on the outside of a pvc tube to be the positive item on this list:

http://www.howstuffworks.com/vdg1.htm

Oh and btw for the belt I'm going to use latex from mcmaster

For the top of the globe I bought 2 bowls from kmart and it says that they are stainless steel non magnetic bowls. Now since they are non magnetic does that mean they are non conductive? I didn't think so but I wanted to check before I go drilling holes in them.

No. It means they are non-ferrous. (they have no iron in them, hence magnets aren't attracted to them) They conduct electricity just fine. One little tip: Grind off the rims of the bowls to minimize leakage and cover the seams with foil tape. Good luck and I can't wait to see the finished product!

Copper isn't magnetic but it's still conductive

Non-magnetic s/s is still conductive to electricity

check instructables.com I think I saw a write up on one.

Read the whole topic before just posting. Oh and btw Da Pneu Kid I saw ur icon was cky and just thought I'd let you know I live in west chester, pa where bam and all the cky people live. Its pretty cool