CNC machine encodersEncoders are used in CNC machines to provide positional feedback while in use, to make sure the machine tool is operating with appropriate speed and accuracy for the job.

An encoder is an electromechanical position feedback device that converts movement data into electrical signals. This digital feedback is used by a machine controller to determine position, speed or direction so it can issue commands to perform a specific function.

Quantum Devices manufactures high-quality, high-performance incremental optical rotary encoders suitable for a wide range of motion control applications, including CNC machining.

Contact Us  Buy Online

How Rotary Encoders are Used in CNC Machines

CNC spindle motor encoderCNC machines use brushless direct current (BLCD) motors, which require electronic commutation. Rotary encoders in CNC machines provide real-time feedback about the angle of the BLDC motor shaft. Shaft angle data is sent to the servo drive, which switches currents to turn stator windings on and off, turning the rotor.

Spindle speed

Rotary encoders are used to monitor spindle speed (rotations per minute, RPM) in CNC machining. Accurate spindle speed control based on the tool and materials in use is critical if you want to optimize for feeds and speeds, tool life, surface finish quality and energy efficiency.

Servo motors

Servo motors are commonly used in CNC lathes and 3-axis machining to move spindles and tables along the X, Y and Z axes. The servo motor turns a rotor shaft that moves the spindle or table. Rotary optical encoders provide feedback about the speed and distance of the shaft movements, as the frequency and line count (resolution) are used to calculate RPM.


Incremental encoder index pulses are commonly used for precision homing. An example would be a lead screw bringing a carriage back to a limit switch. Limit switches, by nature, close at relatively imprecise points, which only provides a rough homing point. The machine can then rotate the lead screw until the Z pulse is high. On an incremental encoder with a 5000 line count, this would mean precision within .072 mechanical degrees (1/5000 of a rotation). That number is multiplied against the lead screw travel.

Robotic machining

Rotary encoders are used in mobile robotics to provide data about motor, gearbox and individual wheel speed, acceleration and position. Rotary encoders are also used in robotic machining applications by acting as secondary encoders installed at each joint to provide feedback to the servo motor controlling each axis. This allows robots to accurately perform milling and drilling type tasks in applications where a classic machine tool would be incompatible with the working environment (such as assembling large components for aircraft).

Rotary encoder for CNC machine

Model QR145 fully enclosed rotary encoder

Harsh environments

Machining center work areas and industrial job sites utilizing machining operations often have harsh environmental conditions. Quantum Devices has developed a fully enclosed optical rotary encoder suitable for harsh production environments including shock, vibration, moisture, EMI, dust, oil, water, metallic chips and other debris – all while overcoming the cost and performance limitations of other fully-enclosed rotary encoders.

More examples of applications for rotary encoders in CNC machining include:

  • Lathe encoder
  • Optical encoder for 5-axis machining
  • Incremental encoder for lathe automation
  • CNC spindle motor encoder
  • CNC controller encoder
  • CNC turret encoder
  • CNC handwheel pulse encoder
  • CNC motor encoder
  • Milling machine encoder
  • Machine position encoder
  • Machine cycle encoder

Quantum Devices engineers are happy to help you choose the best encoder for your specific CNC application. To make a recommendation we’ll need specific information including:

  • Resolution/line count
  • Commutation? (yes/no)
  • Number of poles
  • Shaft style (hollow/solid)
  • Shaft diameter
  • Bolt circle diameter
  • Mounting style
  • Operating voltage
  • Operating temperature (range)
  • Maximum temperature
  • Max RPM
  • Description of application

If already using an encoder for your application, please provide the brand and model number. Quantum Devices offers multiple direct replacement options for other manufacturers’ products, and we can also provide custom encoder configurations.

High-performance Encoders for CNC ApplicationsCNC controller encoders

As a manufacturer and supplier of optical rotary encoders, Quantum Devices provides encoder solutions for a range of CNC machining applications, including CNC manufacturing automation and CNC industrial controls.

Why Quantum Devices?

Quantum Devices encoders are made in the USA, and we have the manufacturing capacity to fulfill both short and long-term needs. Consistent innovations to our product line offer improved accuracy, repeatability, and acceleration/velocity control. What sets us apart from other encoder manufacturers is our commitment to in-house design and production.

Quantum Devices has also been producing our own photodiodes and glass discs for over three decades. We perform our own injection molding and machining in order to control the quality and supply chain for the polymer housings and companion machined components in our encoders. Every encoder that ships from our vertically-integrated operations facility in Wisconsin undergoes stringent quality controls and testing to ensure all products are 100% to specifications.

Contact Quantum Devices online for more information, or to request a custom CNC rotary encoder.

Log In

Forgot Password?

Create an account

Create an account to gain access to all of our 3D models!

Create Account

Create an account to gain access to all of our 3D models!

Forgot Password