Will has been juicin’ to make a Van der Graaf generator. Similar to the Stirling engines, we followed youtube instructions to make it out of trash (soda bottles and soda cans and tape) and failed miserably.
We were mostly following this video https://www.youtube.com/watch?v=vfvjGeOGoBU
Yesterday, we took the gloves off and went to home depot. We used a trash fan motor which is awesome. 3d Printed some pieces for mounting the motor and for mounting the roller on the shaft with a press fit.
Big ole 4″ pvc is the stalk. A flange to mount to the base which is a nice circle wood from the nice wood section of . Used two ikea bowls as the globe. I think it is important to have the upper roller somewhat deeply inside the globe?
We’re using pantyhose as a belt. Sort of the waist area stretched out to be a loop. It is just rubbing on the fixed top pvc roller. Maybe wrapping that in teflon tape would make it even better? The pantyhose is pure nylon. Nylon and pvc are towards opposite ends of the triboelectric series, which is important for the thing to work, but teflon is even farther down.
We used some brushes from home depot as electrical brushes. Might be overkill.
We wrapped the lower roller in more pantyhose to make a bulge. Counterintuitively, this bulge is supposed to keep the belt centered?
We were getting pretty wimpy sparks until we installed to lower brush and properly grounded it. I guess that is really important. Now they are pretty beefy maybe a couple centimeters. You can definitely see them and they sting a bit.
All in all a success!