Here is an interesting video of how a Raleigh bicycle was made in 1945. I lived in Nottingham, England in the 1960s when this factory was still in operation; it was huge and took up many city blocks. In fact the company started out on Raleigh Street in Nottingham in 1887, hence the company name.
An interesting part of the video early on shows a Bottom Bracket shell being made by pressing from a flat piece of steel. I was still building my frames in the 1970s with bottom brackets made in this fashion. (By a French manufacturer named Bocama (BCM); not by Raleigh.)
By the late 1970s early 1980s investment cast bottom brackets and lugs became available that were far superior for a quality hand built frame. Never-the-less many of my old frames from the 1970s with pressed steel BBs are still around.
Interestingly, in the industry of manufacturing bicycles, all the lugs were called “Brackets,” which is where the term Bottom Bracket comes from.
What the film didn’t explain was that when the frame was assembled, a brass ring was placed in a groove inside the socket of the bracket or lug, before the tube was pressed in. When the frame was later placed in a furnace, the brass melted brazing the joint automatically.
Another interesting item not mentioned was that Raleigh parts were a non-standard size and had special Raleigh threading, ensuring that if you bought a Raleigh bike you had to buy Raleigh parts when these needed replacing.
I suggest you click on the “Full Screen” icon, bottom right, to view the video in full screen mode. (Press the “Escape Button” return to normal view.) My thanks to Bruce Chandler for turning me on to this video.