CNC Lathe Codes

What are CNC lathe codes?

CNC lathe codes consist primarily of G-codes and M-codes, along with address codes and canned cycles. These codes form a programming language that controls the operations of a CNC lathe, including tool movement, spindle control, coolant management, and various machining functions.

The codes can range from simple movement commands to complex parametric programming, allowing for precise control and automation of the machining process.

Common G-codes and M-codes in CNC Lathe Programming

This table covers the most commonly used G-codes and M-codes in CNC lathe programming.

Note that some codes may vary slightly depending on the specific CNC control system being used. Always refer to your machine’s programming manual for the exact implementation of these codes.

Code	Category	Function	Notes
G00	Motion	Rapid positioning	Moves at maximum speed to specified position
G01	Motion	Linear interpolation	Moves in a straight line at specified feed rate
G02	Motion	Circular interpolation CW	Creates clockwise circular arc
G03	Motion	Circular interpolation CCW	Creates counterclockwise circular arc
G20	Unit	Inch system	Sets programming to inch system
G21	Unit	Metric system	Sets programming to metric system
G28	Motion	Return to home position	Moves to machine zero point
G96	Spindle	Constant surface speed	Maintains constant cutting speed
G97	Spindle	Constant spindle speed	Maintains constant RPM
M03	Miscellaneous	Spindle on clockwise	Starts spindle rotation clockwise
M04	Miscellaneous	Spindle on counterclockwise	Starts spindle rotation counterclockwise
M05	Miscellaneous	Spindle stop	Stops spindle rotation
M30	Miscellaneous	Program end	Ends program and resets
G00	Motion	Rapid positioning	Moves at maximum speed to specified position
G01	Motion	Linear interpolation	Moves in a straight line at specified feed rate
G02	Motion	Circular interpolation CW	Creates clockwise circular arc
G03	Motion	Circular interpolation CCW	Creates counterclockwise circular arc
G04	Dwell	Dwell	Pause program for specified time
G20	Unit	Inch system	Sets programming to inch system
G21	Unit	Metric system	Sets programming to metric system
G28	Motion	Return to home position	Moves to machine zero point
G40	Compensation	Tool nose compensation cancel	Cancels tool nose radius compensation
G41	Compensation	Tool nose compensation left	Applies left tool nose radius compensation
G42	Compensation	Tool nose compensation right	Applies right tool nose radius compensation
G50	Setting	Set coordinate system	Establishes a coordinate system
G54	Coordinate	Work coordinate system 1	Selects work coordinate system 1
G55	Coordinate	Work coordinate system 2	Selects work coordinate system 2
G56	Coordinate	Work coordinate system 3	Selects work coordinate system 3
G57	Coordinate	Work coordinate system 4	Selects work coordinate system 4
G58	Coordinate	Work coordinate system 5	Selects work coordinate system 5
G59	Coordinate	Work coordinate system 6	Selects work coordinate system 6
G70	Cycle	Finishing cycle	Performs finishing cycle
G71	Cycle	Stock removal in turning	Performs rough turning cycle
G72	Cycle	Stock removal in facing	Performs rough facing cycle
G73	Cycle	Pattern repeating	Performs pattern repeating cycle
G74	Cycle	Face grooving	Performs face grooving cycle
G75	Cycle	Outer/Inner diameter grooving	Performs OD/ID grooving cycle
G76	Cycle	Threading cycle	Performs multi-pass threading cycle
G90	Mode	Absolute programming	Sets absolute coordinate programming
G91	Mode	Incremental programming	Sets incremental coordinate programming
G94	Feed	Feed per minute	Sets feed rate in units per minute
G95	Feed	Feed per revolution	Sets feed rate in units per revolution
G96	Spindle	Constant surface speed	Maintains constant cutting speed
G97	Spindle	Constant spindle speed	Maintains constant RPM
G98	Return	Return to initial level	Returns to initial Z-axis level in canned cycles
G99	Return	Return to R level	Returns to R-axis level in canned cycles
M00	Miscellaneous	Program stop	Stops program execution
M01	Miscellaneous	Optional stop	Stops program if optional stop switch is on
M03	Miscellaneous	Spindle on clockwise	Starts spindle rotation clockwise
M04	Miscellaneous	Spindle on counterclockwise	Starts spindle rotation counterclockwise
M05	Miscellaneous	Spindle stop	Stops spindle rotation
M06	Miscellaneous	Tool change	Performs automatic tool change
M08	Miscellaneous	Coolant on	Turns on flood coolant
M09	Miscellaneous	Coolant off	Turns off all coolant
M10	Miscellaneous	Chuck clamp	Clamps the chuck
M11	Miscellaneous	Chuck unclamp	Unclamps the chuck
M19	Miscellaneous	Oriented spindle stop	Stops spindle at a specific orientation
M30	Miscellaneous	Program end	Ends program and resets
M41	Miscellaneous	Gear select 1	Selects spindle gear range 1
M42	Miscellaneous	Gear select 2	Selects spindle gear range 2
M43	Miscellaneous	Gear select 3	Selects spindle gear range 3
M44	Miscellaneous	Gear select 4	Selects spindle gear range 4
M98	Miscellaneous	Subprogram call	Calls a subprogram
M99	Miscellaneous	Subprogram end	Ends a subprogram and returns

Example of a simple CNC lathe program:

O1000 (SIMPLE TURNING PROGRAM)
G21 G40 G95 G97
G28 U0 W0
T0101 (TURNING TOOL)
G50 S2000
G96 S180 M03
G00 X50.0 Z0.1
G01 X-1.6 F0.15
G00 X50.0 Z2.0
G28 U0 W0
M30

This program does the following:

Sets up the machine (metric, tool comp off, feed per rev, constant RPM)
Returns to home position
Selects tool 1
Sets max spindle speed and turns on constant surface speed
Moves to starting position
Performs a facing cut
Retracts
Returns home
Ends the program

While these codes are standardized to some extent, there can be variations between different machine manufacturers and controllers.

Gavin Yi

Gavin Yi is a distinguished leader in precision manufacturing and CNC technology. As a regular contributor to Modern Machine Shop and American Machinist magazines, he shares expertise on advanced machining processes and Industry 4.0 integration. His research on process optimization has been published in the Journal of Manufacturing Science and Engineering and International Journal of Machine Tools and Manufacture.

Gavin serves on the National Tooling & Machining Association (NTMA) board and frequently presents at the International Manufacturing Technology Show (IMTS). He holds certifications from leading CNC training institutions including Goodwin University’s Advanced Manufacturing program. Under his leadership, Shenzhen Yijin Hardware collaborates with DMG Mori and Haas Automation to drive innovation in precision manufacturing.

Contents

What are CNC lathe codes?

Common G-codes and M-codes in CNC Lathe Programming

Example of a simple CNC lathe program:

Gavin Yi

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