CNC Milling Machine Spindle [Complete DIY Guide ...
The Spindle Taper refers to the size and type of tool holder that will fit the spindle. For example, the R8 taper that was introduced with the original Bridgeport manual milling machines is very popular. There are a huge number of spindle taper possibilities, so I'll just focus on two common ones for DIY CNC Milling Machines: R8 and BT 30.