Things I don't understand - Part One of Many
Today the modern version of Biro's pen, under the brand name BiC Cristal, sells 20 million pens throughout the world every day.
OK, I know how many things are made including how you forge chain links, I know how you brick up a well from the top down, how you get ships into bottles - but how do you make ball bearings? I understand how shot towers worked; I also know how specialist Ball Bearing factories were hugely valuable during the War when Germany relied on Swedish production. But how do you make millions of them every day to high standards of accuracy? Cast them and then grind them a bit? Please tell me - I have been trying to find out for years.