Computer Numerical Control

CNC DC-Motor Spindle:

The spindle in the image is designed to hold cutting bits with a 1/8" shank, the collet holds the tooling; In this case a Mill that's been CNC'd is using the spindle to hold Carbide-End-Mills, this DC motor will spin quietly at 25,000 RPM, it's rated at 2200-Watts.

Being 2.2KW the motor needs water cooling, along with that a small water pump to keep water circulating so the DC-motor stays at a nice cool operating temperature, the water pumps are much like the ones used in aquariums.

The DC-Motor-Spindle:

  • Provides a consistent torque curve, the higher the voltage the faster the speed without a big loss of torque.
  • Can reverse direction by reversing polarity, great for tool changes.
  • Can be monitored by the use of encoders and the PC; steppers can be timed based on spindle RPM.
  • Can be controlled with machine software using Logic and PWM (Pulse-Width-Modulation),

The AC Spindle:

  • Control using a "" TRIAC Opposed to PWM
  • High Power
  • Fast

The Universal-Motor AC/DC Spindle:

  • These are common motors found in household items like the your Fan, Vacume, or Drill, these spindle motors can operate on a DC or AC power source and have brushes, these motors can be controlled by either method noted above.

Properties of a Universal Motor.

Amperage, if you choose to use a water cooled spindle that requires 2.2KW, you will need to have a power supply that provides:

  • 12V 184A
  • 24V 92A
  • 48V 46A

For the 300-Watt:

  • 12V 30A
  • 24V 15A
  • 48V 7.5A

These are Minimum values and may ware out the power supply sooner than later, it's always a good idea to supply more Amperage than required.

Please also take note that these values can kill you or someone else, use extreme caution when dealing with electricity (It only takes once).

The Chuck:

Chucks are used by larger spindle motors and vary in design and application. The most common chuck seen on the metal CNC lathe is the "3-Jaw self centering" chuck.

The chuck found on the hand drill is also found on some machines, however they are not balanced like the larger self centering chucks noted above.

Tooling Shank:

This is the O.D (Outside Diameter) of the cutting bit shaft, the shank is the part of the drill-bit or tool that goes into the chuck or "collet".


The collet is what crimps onto the tool shank when the nut is tightened, in the case of the image, the collet is just on the other side of the nut located at the end of the motor shaft. This Spindle has an interchangeable spindle for 1/8" cutting bits.




You can control the spindle using Arduino or a PLC, even program a GUI for a project. Three methods used for the C++ programming include:

  • Switching the motor on and off manually (monitor an I/O). Using a mechanical switch, or sensor.
  • Switch the motor on/ off or change direction using a GUI, (PHP VB C#).
  • Switch the motor on/ off using time (Pre-defined "Delay").

Alternately more than one or all of these features can be used together, you can have a GUI to monitor the situation, a sensor to protect things, and a sketch that delays certain motors.