When I first built my machine I found after just a little operation there were small erosion holes forming in the outer foil sheets where the shunt ball ends contact the foil and got tired of replacing the foil. The simple cure I came up with was to make the replaceable foil bands seen on the Leyden jars on my machine. They protect the foil sheets on the jars from any dings and the slight erosion caused by the shunt balls contact the foil.

The same erosion still happens initially on the surface of the foil strips when they are first installed, then appears to stop once enough contact area has been made between the shunt ball ends and the foil strips. This has happened with both the toothpick holder jars seen in the photos of my machine and the new protector tubing jars with 2.5" wide foil. After several weeks of regular daily operation with both sets of jars there was no additional erosion in the foil strips after the initial small amoun.

Here's to make the foil strips...
Cut foil strips 2" wide. Fold the long edges in 1/2" from each side, then fold the strip in half again toward the previous folds to form a 4 layer strip 1/2" wide. Wrap the foil strip around the jar with the two edges down and the best looking side out and cut excess foil off so the ends overlap about 1/8". With the strip pulled tight around the jar so the ends are positioned where the visible end of the foil sheet is, tape the ends together,

Once the Leyden jars are in place on the machine, position the foil strips so the shunt ball end is centered on the strip, then put a piece of tape a bit wider then the strip over the strip's joint to keep it from moving.

Bruce

I remember making my own Wimshurst machine for an assignment in 9th grade science class circa 1964. It was made of two 78 rpm records with aluminum foil cut into truncated triangles that were taped to the records. They revolved on a wooden dowel with wooden spools as spacers. I made a crank and devised a simple pully system with one of the rubber bands that turned the spools crossed in a figure 8 so the records revolved in opposite directions. The records were probably made of bakelite. Coat hanger wire held aluminum foil "brushes" and relayed the static electricity to coat hanger wire discharge points. The darned thing actually worked, and I got an A. From a long-time electronics buff geek and would-be steam punk...I guess.