CNC machining
A CNC starts with a piece of metal, sometimes called a "bill".
That piece of metal may have been cast, forged, or rolled (extruded between rolls, kind of like limited forging that only makes flat objects with straight grains like planks).
It was put into a fairly standard machine tool with position sensing and motors on the control knobs. It's basically just a robotic mechanic. You use a rotary cutting tool to cut off all the metal that is not your crank. 3D metal etched sketch, using computer interpolation so the drawn circles look very smooth.
Advantages of CNC machining
You can't use sharp inside corners on a forging, you'll never be able to get the part out of the die. So all interior corners must be wider than 90 degrees and have rounded edges (if you have a die (die) trying to form sharp corners, it will cut rather than push the metal into place.
The CNC doesn't impose such a limit, but to get a nice fillet you may have to change the tool to make one last pass. (You use a flat tool to remove most of the metal on the flat areas, and a round nose tool to form an inner radius where needed.) So eliminating stress rises means more expensive machining time.
Why choose CNC?
So why use CNC? It excels at making small numbers of complex shapes. In fact, they are just things that make dies (called tools and dies) to do the forging. (Thus, CNC technology actually reduces the "tool" costs associated with forging!) It got the biggest boost from missile people. If you're only going to make 30 things, CNC is only for complex shaped parts, like the landing gear struts on that fighter jet.
The Peace Dividend has left a bunch of shops with CNC overcapacity. Since the cost of the machine "idling" can easily be more than half the cost of running it all on billable work, it needs to find something to do, or the bank may call the auctioneer. They looked around for something to earn some money to pay the rent. Boutique bike parts and other stuff, where "rocket science" adds enough marketing appeal to overcome CNC inefficiencies, is what these stores lock in. (For others, check out golf clubs or motorcycle and car jumping parts)
Although large and heavy, the press is a very simple "low tech" machine with very low maintenance requirements. In most cases, they are too stupid to break. The most complex part of the press is the sensors that make sure the operator's body is out of the way before it starts to move. It's either a single motor connected to a pump and a large hydraulic piston, or it's a "drop forge," a chunk of metal that has a mechanism that picks it up and then lowers it. No fancy measuring devices. There are no computers unless they have a robot next to them to load and unload finished parts.
