How a valve is made

This is a fantastic video about the manufacture of valves in the Mullard factory in Blackburn.

It starts with an description of the parts that make up a valve and runs through the entire manufacturing process.

At 15:32 there is a view of the automated ECC82 assembly line.

21 minutes in there's a explanation of how the valve bases are made and some fantastic automatic glass melting / forming machinery.

I also like the lack of dumbing-down in this film, and the assumption that the viewer is intelligent and informed.  How many Discovery Channel programmes would dare to use the line:

"You will remember that during the manufacture of the heater wire, the fine tungsten filament was wrapped around a molybdenum core which served as a mandrel during the winding and as a support during the subsequent operations."

Brilliant!