We found a sheet from a company called Vactite

it lists the ratio of wire to hole diameters for a given number wires.

The ratio varies from 2 at 2 (obvious) to 9 for 61 wires and looks to gently increase almost linearly thereafter but no data listed.

so the our spreadsheet is now complete. But we figured the easiest way to find out is to throw a handfull of ball bearings into rings of given diameter and shake. Pick off the proudest and count.

Now the big one - how many banjo players can you fit on the point of a pin.......................