There are many different sizes of CNC Milling Machines. There are also Vertical Spindle machines and Horizontal Spindle machines out in the marketplace. The most popular is probably the Vertical Spindle mill. There are also machining centers and knee mills available.
CNC Retrofits are mills are common. Probably the most common is the CNC Retrofit
of a Bridgeport Knee Mill. These mills
used to be considered full production machines, but are now prized by
hobbyists. Machining Centers have now
taken over production with Multiple Tool Changers, which give you more
operations and faster cycle times.