Static Cling??

[orelinde]

okay we run the robot. and then afterwards we get zapped everytime we touch something around the robot. we did use carpets as conveyor belt. and the wiring has been carefully checked and rechecked. the grounding multiple checks on it. i can walk by and then touch metal and get zapped every time. What can we do to stop this from happening or is this normal?

[Doc Wu]

Originally Posted by orelinde

okay we run the robot. and then afterwards we get zapped everytime we touch something around the robot. We did use carpets as conveyor belt. and the wiring has been carefully checked and rechecked. the grounding multiple checks on it. I can walk by and then touch metal and get zapped every time. What can we do to stop this from happening or is this normal?

I'm not sure what you can do to stop it, but as a start, I can tell you why it's happening - just look at a Van DeGraf generator. If you have a belt, you've got good start on one.

I got a good jolt off our robot once too! We have a rubber belt on PVC plastic rollers. Carpet would be even more likely to make static, I would think.

You might try making something to keep the charge at the top and bottom of the belt thee same and drain off the charge.

You might try spraying the belt with a product like "Static Guard" too.

[orelinde]

okay forgive me for sounding not quite with it but well i am not quite with it could you please explain how to "keep the charge at the top and at the bottom and drain off the charge" We have tried to build a safe robot but it seems to me that getting zapped while fun for some *looks at son* i did not enjoy the experience. *chuckles*


Other then the electrical issue i have learned as a parent so much froom this experience. i love seeing the students accidently learning in a fun positive way and wish we have this when i was growing up.

[Eldarion]

Originally Posted by orelinde

okay forgive me for sounding not quite with it but well i am not quite with it could you please explain how to "keep the charge at the top and at the bottom and drain off the charge" We have tried to build a safe robot but it seems to me that getting zapped while fun for some *looks at son* i did not enjoy the experience. *chuckles*


Other then the electrical issue i have learned as a parent so much froom this experience. i love seeing the students accidently learning in a fun positive way and wish we have this when i was growing up.

The way I understand it is that you would place metal "brushes" on the top of the belt and the bottom roller (where you would normally tap off charge on a VanDegraff), and short the two together.

[DjAlamose]

Please see thread

http://www.chiefdelphi.com/forums/sh...&highlight=van

[gondorf]

just a thought but the carpet conveyor belts are on wood spindles. doesnt wood have no conductivity? i mean if it is running on wood then the carpet shouldnt be giving static to the frame.

[Alan Anderson]

Static electricity thrives on insulation. No, really. If your belt and spindles were conductive, the electrons would not be accumulating and giving you shocks. It's the physical motion of the material that pulls the electrons along and drops them all off in the same place.

To drain off the charge, you can use the sort of wire-brush thing some aircraft have at the trailing edges of the wing, or you can try putting some pointy metal aiming at the top and bottom rollers, connected to the metal frame of the robot.

[Rickertsen2]

Maybie a stipid idea, but how about Anti-static laundry spray?

They sell it at the dollar store by my house. I use it as potato cannon fuel. It definately works at preventing static on sweaters and whatnot.

[Eldarion]

Originally Posted by Rickertsen2

Maybie a stipid idea, but how about Anti-static laundry spray?

They sell it at the dollar store by my house. I use it as potato cannon fuel. It definately works at preventing static on sweaters and whatnot.

If you are using it as potato cannon fuel, it sounds pretty volatile. Wouldn't it evaporate and therefore quit working relatively quickly?

Also, I wonder what would happen if a spark did occur, and a flammable substance was sprayed with that stuff. Big fireball?

[Alan Anderson]

Originally Posted by mechanicalbrain

I recommend seeing if you can isolate belts from all conductive materials. For example, rubber spacers, plastic screws, and so forth.

That's exactly the wrong thing to do in this case. If you can manage to connect the belts etc. to a conductive frame effectively, the problem will be much reduced.

And absolutely do not try to fix things by connecting anything to your electrical ground. What you'll end up with is high voltages on your wiring, which will very likely damage the electronics each time a static zap occurs.

[Tom Bottiglieri]

Originally Posted by Alan Anderson

That's exactly the wrong thing to do in this case. If you can manage to connect the belts etc. to a conductive frame effectively, the problem will be much reduced.

As Alan said, the rollers themselves are fairly small, and any excess electrons will be quite anxious to jump off the the next available particle party boat. You can easily drop the static charge in your roller by connecting them to the frame, and connecting the frame to the ground (if your wheels dont do a good enough job, drop some long zip ties to the floor) This will induce a charge in the frame material and give the static in the rollers a straight path to the ground.

[gondorf]

small rollers?!?!

our top spindle has a 15" diameter and is made of solid plywood.

it weighs 20 pounds

you are right though. perhaps another ground bolt will work if we add a drag chain.

just a thought but if your robot gives a static discharge to the inspector do you think he will fail you?

[steven114]

Just make sure you touch the robot first!

[Rickertsen2]

Originally Posted by Eldarion

If you are using it as potato cannon fuel, it sounds pretty volatile. Wouldn't it evaporate and therefore quit working relatively quickly?

Also, I wonder what would happen if a spark did occur, and a flammable substance was sprayed with that stuff. Big fireball?

I think the flammable part is just a solvent or pressurized propellent or both. In any case, that part evaporates while the active ingredient sticks around. There is a label on the bottle that says something to the effect "for risk of fire, do not peel apart clothes while spraying."

Some basic background on static:
"static" does not behave like the electricity you are used to. It occurs when you have an area with a different density of electrons than the areas around it. Think electrical pressure difference." The only way to get rid of this is by direct contact with an area of a lower electron density or through a conductor that connects to an area of lower charge density. The ground can be though of as a vast electron sink. If you can connect the thing you are having problems with to the the ground through a conductor such as some bare wire touching the ground, you might be able to solve your problem. It would equalize the charge density. At the very least, you could connect to a large conductor(such as your frame) , which would spread the charge out over a larger area, decreasing its density.

[Eldarion]

Originally Posted by Rickertsen2

Some basic background on static:
"static" does not behave like the electricity you are used to. It occurs when you have an area with a different density of electrons than the areas around it. Think electrical pressure difference." The only way to get rid of this is by direct contact with an area of a lower electron density or through a conductor that connects to an area of lower charge density. The ground can be though of as a vast electron sink. If you can connect the thing you are having problems with to the the ground through a conductor such as some bare wire touching the ground, you might be able to solve your problem. It would equalize the charge density. At the very least, you could connect to a large conductor(such as your frame) , which would spread the charge out over a larger area, decreasing its density.

The only problem I could think of is that the balls themselves are pretty nice charge carriers, such that the robot, even while equalized internally, would develop an overall charge. The same would hold true with the balls.

Then again, maybe this is only if a team is shooting a lot of balls!