G-Code - Quick Guide.pdf - CNC(1) - czupur_n

Ivan Irons | CNC Information | G-Code Quick Guide

Ivan Irons | CNC Information | G-Code Quick Guide

What is this guide?

A number of people ask me about G-Code on a consistent basis. It is one of those

“unknown” things for people when they learn CNC. It is a computer language and that makes

some people nervous. I wrote this guide to help people ease into g-code and to alleviate their

anxiety about it.

What is G-Code?

G-Code programming is a very robust and simple language. G-codes are what CNC

Machines run on. A CNC control program process the g-code line by line and send this

information to the machine. The machine then takes this information and makes precise

movements. Yes, it is as simple as that.

Where does G-Code come from?

That is simple enough, it come from your CAM program. When you process your

design in your CAM program you pick out various machining parameters and inputs. You

match it up with the CNC Machine the part will be run on and then Post-Process. You CAM

program then spits out very precise G-Code for your machine and your part. If you make

changes to your design, you will need to go through the CAM process again.

Post Processors

A post processor is a specific way you CAM Program will process your design. There

are standard ones and custom ones. If a standard one doesn’t work for you, most good CAM

Software gives you the option to customize the post processor to fit your needs.

Canned Cycles

We won’t be covering Canned Cycles here. There are G-Codes that do pertain to

Canned Cycles. This guide is targeted toward beginner to intermediate CNC Learners.

The Big G-Code List

What comes next is a listing of what each g-code means. You can use this list if you

are having a problem and are trying to decipher what is going on in your program. A note of

caution…this is a generic list. Many manufacturers don’t exactly adhere to this list and change

the codes on a whim. You will need to be familiar with your own CAM Program, CNC Control

Software and CNC Machine to determine if they have changed something. It is not something

I can do for you.

http://www.CNCInformation.com

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Ivan Irons | CNC Information | G-Code Quick Guide

G0 or G00 – Rapid Movement

The most rapid movement the CNC Machine can make to the next position. If moving in

multiple axis, each axis will move as fast as they can independently of one another.

G1 or G01 – Linear Movement

A straight move with a speed defined by an “F.” [F=Feedrate] If moving in multiple axis, the

machine will move in each axis until it reaches its defined position.

G2 or G02 – Interpolation Clockwise

A circular movement in 2-axis in a clockwise motion. Will create an arc to a specified radius

defined by an R or I/J combination.

G2 or G03 - Interpolation Counter Clockwise

A circular movement in 2-axis in a counter-clockwise motion. Will create an arc to a specified

radius defined by an R or I/J combination.

G4 or G04 – Dwell

Machine will dwell once reached position to a user defined time, noted by a “P”

G9 or G09 – Exact Stop/Exact Position

Machine will not traverse to next line of code until it locates exactly to specified position.

G17 - XY plane selection

G18 - ZX plane selection

G19 - YZ plane selection

G20 - Machine in inch

G21 - Machine in MM

G28 - Return to Reference Position

Normally machine home.

G30 - Return to 2 nd reference position

G40 - Cutter Compensation Cancel

G41 - Cutter Compensation Left

G42 - Cutter Compensation Right

G43 - Tool Length Compensation +

G44 - Tool Length Compensation -

http://www.CNCInformation.com

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Ivan Irons | CNC Information | G-Code Quick Guide

G54-G59 - Work Coordinate Systems

User defined, XYZ

G68 - Coordinate Rotation

G69 - Coordinate Rotation Cancel

G73 - Peck Drilling Cycle

G76 - Boring Cycle

G80 - Cancel Canned Cycle

G81 - Drilling Cycle

G82 - Drilling Cycle

G83 - Pecking Cycle

G84 - Tapping Cycle

G85 - Boring Cycle

G86 - Boring Cycle

G87 - Back Boring Cycle

G90 - Absolute Command

G91 - Incremental Command

G92 - Programming of Absolute Zero

G94 - Feed Per Minute

G95 - Feed Per Revolution

G98 - Return to initial point in canned cycle

G99 - Return to R point in canned cycle

http://www.CNCInformation.com

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Ivan Irons | CNC Information | G-Code Quick Guide

The Future of G-Code

The future of g-code is in jeopardy. Kind of…but don’t hold your breath. There are

changes going on to try to create a new standard. A new standard where you can go straight

from CAD or CAM right to the CNC machine.

This is basically an attempt to try to eliminate a step in the CNC Process. Others have

tried to update or eliminate g-code before. So far, its simplicity has won out. It has survived.

Is it worth learning a little about it today? Yes.

2” Square G-Code Example

The numbers on the left of the G-Code are the sequence numbers of the code and the

order it will be executed in. I have added notes after different actions to let you know what that

line of code means. My note starts with a “-“ then continues. A “-“ means nothing in G-Code.

N0000 (Filename: 2INSquare.txt) – Name of File

N0010 (Post processor: Plasma.post) – Name of Post Processor Used

N0020 (Date: 8/1/2007) - Date G-Code was generated

N0030 G20 (Units: Inches) – Measurement Units Used

N0040 G53 - Machine co-ordinate system

N0050 G90 – Absolute Programming

N0060 G40 – Tool radius compensation off

N0070 F1 – Feedrate of 1” per min

N0090 (Part: Square) – name of the part

N0100 (Process: Plasma, DEFAULT, Plasma, 0.01 in kerf) – Tool to be used

N0110 G00 – Go to Home

N0120 X0.1113 Y-0.0904 – Move to this exact X, Y position

N0130 G04 P2000 – Pause for 2 seconds, this is in milliseconds

N0140 M03 – Fire the plasma torch

N0150 G04 P500 - Pause for .5 seconds, this is in milliseconds

N0160 G03 X0.0000 Y-0.0050 I-0.1113 J-0.0298 F40.0 – move to this X, Y

position in an arcing movement at a feedrate of 40 inches per min

N0180 G01 Y2.0000 – Travel in the Y+ direction for 2 inches to X0, Y2

N0200 G01 X2.0000 – Travel in the X+ direction for 2 inches to X2, Y2

N0220 G01 Y0.0000 – Travel in the Y- direction for 2 inches to X2, Y0

N0240 G01 X0.0000 – Travel in the X- direction for 2 inches to X0, Y0

N0250 G03 X-0.1113 Y-0.0904 I0.0000 J-0.1152 – move to this X, Y position in an

arcing movement

N0260 M05 – Turn off the plasma torch

N0270 G04 P2000 – Pause for 2 seconds, this is in milliseconds

N0280 G00 – Move to Home

N0300 M30 – End Program

Do I need to be a G-Code Expert?

In a word, no. You will probably need to know how to quickly scan your G-Code if you

are having problems during your machining simulation. Other then that G-Code and a CNC

program are throwaway programs for the most part.

http://www.CNCInformation.com

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G-Code - Quick Guide.pdf

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