CNC PROGRAMMING G-Code basics

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G-Code from the Machine’s Perspective

There are a handful of basic concepts you should know before we dive into what individual g-codes do and how to use them. Most importantly, you must understand what a computer language is and how to think about it.G-Code is a computer language aimed at telling your machine what to do. The trouble with computer languages like g-code is that unlike people, machines are very literal. They assume you know exactly what you want, they don’t question you about it, and they immediately try to comply, even if that means hurting themselves!

G-Code Skill Level

For that reason, you need to adopt an approach of being protective of your machine, perhaps even over protective bordering on paranoid. It will do exactly what you tell it to even if that means rapiding a spinning cutter with 20HP behind it directly into your expensive fourth axis and destroying it. There’s no need to be afraid of g-code, but it is important to understand it and to respect it in order to be successful. Getting to that stage is another excellent reason to spend time learning the g-code. It will give you insights into your machine that enable you to extract more performance and to protect it better from accidents.                                                       (http://www.cnccookbook.com/CCCNCGCodeBasics.htm)

Code
Category
Function

Notes

Tutorials
G00
Motion
Move in a straight line at rapids speed. XYZ of endpoint G00 and MDI.

Linear Motion: G00 and G01

G01
Motion
Move in a straight line at last speed commanded by a (F)eedrate XYZ of endpoint G01 and MDI.

Linear Motion: G00 and G01

G02
Motion
Clockwise circular arc at (F)eedrate XYZ of endpoint

IJK relative to center

R for radius

G02 / G03 Tutorial and Examples
G03
Motion
Counter-clockwise circular arc at (F)eedrate XYZ of endpoint

IJK relative to center

R for radius

G02 / G03 Tutorial and Examples
G04
Motion
Dwell: Stop for a specified time. P for milliseconds

X for seconds

Precise Timing and Speed: Dwell, Exact Stop, Backlash Compensation
G05
Motion
FADAL Non-Modal Rapids
G09
Motion
Exact stop check Precise Timing and Speed: Dwell, Exact Stop, Backlash Compensation
G10
Compensation
Programmable parameter input
G15
Coordinate
Turn Polar Coordinates OFF, return to Cartesian Coordinates G15/G16 Polar Coordinates
G16
Coordinate
Turn Polar Coordinates ON G15/G16 Polar Coordinates
G17
Coordinate
Select X-Y plane CNC G-Code Coordinates
G18
Coordinate
Select X-Z plane CNC G-Code Coordinates
G19
Coordinate
Select Y-Z plane CNC G-Code Coordinates
G20
Coordinate
Program coordinates are inches G20 and G21: Unit Conversion
G21
Coordinate
Program coordinates are mm G20 and G21: Unit Conversion
G27
Motion
Reference point return check G28: Return to Reference Point
G28
Motion
Return to home position G28: Return to Reference Point
G29
Motion
Return from the reference position G28: Return to Reference Point
G30
Motion
Return to the 2nd, 3rd, and 4th reference point G28: Return to Reference Point
G32
Canned
Constant lead threading (like G01 synchronized with spindle)
G40
Compensation
Tool cutter compensation off (radius comp.)
G41
Compensation
Tool cutter compensation left (radius comp.)
G42
Compensation
Tool cutter compensation right (radius comp.)
G43
Compensation
Apply tool length compensation (plus)
G44
Compensation
Apply tool length compensation (minus)
G49
Compensation
Tool length compensation cancel
G50
Compensation
Reset all scale factors to 1.0
G51
Compensation
Turn on scale factors
G52
Coordinate
Local workshift for all coordinate systems: add XYZ offsets
G53
Coordinate
Machine coordinate system (cancel work offsets)
G54
Coordinate
Work coordinate system (1st Workpiece)
G55
Coordinate
Work coordinate system (2nd Workpiece)
G56
Coordinate
Work coordinate system (3rd Workpiece)
G57
Coordinate
Work coordinate system (4th Workpiece)
G58
Coordinate
Work coordinate system (5th Workpiece)
G59
Coordinate
Work coordinate system (6th Workpiece)
G61
Other
Exact stop check mode Precise Timing and Speed: Dwell, Exact Stop, Backlash Compensation
G62
Other
Automatic corner override
G63
Other
Tapping mode
G64
Other
Best speed path
G65
Other
Custom macro simple call Subprograms and Macros
G68
Coordinate
Coordinate System Rotation G68 and G69 Tutorial and Examples
G69
Coordinate
Cancel Coordinate System Rotation G68 and G69 Tutorial and Examples
G73
Canned
High speed drilling cycle (small retract)
G74
Canned
Left hand tapping cycle
G76
Canned
Fine boring cyle
G80
Canned
Cancel canned cycle
G81
Canned
Simple drilling cycle
G82
Canned
Drilling cycle with dwell (counterboring)
G83
Canned
Peck drilling cycle (full retract)
G84
Canned
Tapping cycle
G85
Canned
Boring canned cycle, no dwell, feed out
G86
Canned
Boring canned cycle, spindle stop, rapid out
G87
Canned
Back boring canned cycle
G88
Canned
Boring canned cycle, spindle stop, manual out
G89
Canned
Boring canned cycle, dwell, feed out
G90
Coordinate
Absolute programming of XYZ (type B and C systems)
G90.1
Coordinate
Absolute programming IJK (type B and C systems)
G91
Coordinate
Incremental programming of XYZ (type B and C systems)
G91.1
Coordinate
Incremental programming IJK (type B and C systems)
G92
Coordinate
Offset coordinate system and save parameters
M-Codes
Code
Category
Function

Notes

Tutorials
M03
M-Code
Spindle ON (CW Rotation) M03 and MDI.
M04
M-Code
Spindle ON (CCW Rotation)
M05
M-Code
Spindle Stop M05 and MDI.
M06
M-Code
Tool Change
M30
M-Code
End of Program, Rewind and Reset Modes