Originally Posted by
bobotech
If what you are drawing is the "fixed cup", then something is odd. Normally the fixed cup has the solid ring around the end of the threads to lock it down against the BB shell when it is fully tightened. What you have pictured is that the threads extend all the way to the end of the cup with no lip.
Well, the OP's bike is a Hercules, and those old British bikes did things differently. Not only the odd-ball 26tpi bottom bracket and assorted Whitworth threaded fasteners in various places, but the fixed cups sometimes lacked that shoulder you mention (both my Superbe and my wife's Sports are like this), instead expecting that the fixed cup be driven into the shell until it bottoms out at the end of the threads. The reverse threading on the cup ensures it will stay in place in use. This type of cup often has 5/8" flats for a tool to grasp, both on the adjustable and the fixed cups. For these either the Park HCW-11:
or the
BikeSmithDesign bottom bracket tool work best:
