Posts Tagged ‘learn cnc’

CNC General Overview

Wednesday, November 12th, 2008

CNC

Many experts say that a CNC Machine is one of the best tools a person can have whether they are doing woodworking or other types of work. This is a versatile tool that can make things a lot easier for the person using it.

CNC actually stands for computer numerical control and it is a machine that works through the use of a computer that reads a particular code called a G-Code to make certain parts. This computer does the work by cutting away materials that the code tells it to cut. The machine has certain parameters that it works within and these are determined by a software program.

Before CNC machines, there were NC machines which stands for numerically controlled and the problem with these were that you could not change their parameters that they worked within. As the popularity of these machines grew the DIY CNC came into being but used the old NC styled hardware. Eventually the programs became more sophisticated and used floppy disks instead of punched tape to transfer the codes to the machine until it eventually evolved to what is in place today.

CNC machines were responsible for changing the manufacturing industry. These machines could produce curves, straight lines or complex structures in 3-D without much human interaction. In fact, the machining steps that were required for a human to do were reduced to just a few steps.

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Let’s go under the hood of the G-Code program

Tuesday, October 7th, 2008

gcode program

Next, we are going to go through an example of cutting out a 2” square with a CNC Plasma Cutter.  Then we will look at the G-Code to see what is happening.

2” Square G-Code:
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
򾛾 G20 (Units: Inches) – Measurement Units Used
򾜈 ᯱ - Machine co-ordinate system
N0050 G90 – Absolute Programming
N0060 ᯤ – 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 Ͱ.1113 Y-0.0904 – Move to this exact X, Y position
N0130 G04 P2000 – Pause for 2 seconds, this is in milliseconds
N0140 ḗ – Fire the plasma torch
򾝶 G04 P500 - Pause for .5 seconds, this is in milliseconds
N0160 G03 Ͱ.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 ᮽ 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, ͼ
N0220 G01 Y0.0000 – Travel in the Y- direction for 2 inches to X2, Y0
N0240 ᮽ X0.0000 – Travel in the X- direction for 2 inches to X0, ͺ
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
򾟮 G04 P2000 – Pause for 2 seconds, this is in milliseconds
N0280 G00 – Move to Home
N0300 M30 – End Program

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What is G-Code?

Sunday, October 5th, 2008

cnc tutorials

G-Code is the common name for the programming language of CNC Machines.Somewhat of a general, catchall term for CNC programming language.  Very few machines adhere to this standard today.  There are as many varations as there are manufacturers.

This is how I think of G-Code.  It is a simple language built off of the Cartesian Coordinate System for motion control.  That is a mouthful.  I don’t know if that is exactly right, but you will get my meaning in a second when we go through some code line by line.  You will remember your High School Geometry soon enough.  For the real pros out there, you know there is much more to G-Code then that, but it is a good place to start thinking about it.

You will see many variations of the G-Code name like:
Gcode
gcode
G-Code
g-code
G Code
G-Code

Are there other “Codes?”
In a word…Yes.We will get to that information in just a minute.  G-code is also the name of any command in a CNC program that begins with the letter G.  G-Codes generally tell the machine to perform an action.  G-Codes can tell machines to move a certain distance in the X-Axis for example.  Or, make a rapid move to another location.  Or, move in an arcing fashion while milling.  An on and on and on.

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how can I learn more about G-Code

Saturday, October 4th, 2008

learn cnc

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.  What do I mean by that?  Let me explain.

Let’s look at a specific design.  Let’s say a 12” by 12” square.  You build your model, run it through your CAM Software and create a CNC Program made up of G-Code instructions to your machine.  Say tomorrow the job requirements change to a 24” by 24” square.  Do you go into your G-Code line by line and change the code?  Most people wouldn’t.  They would go back into their CAD or CAM program and scale the square up to 24” by 24”.Then postprocess the job to get their new CNC Program.

There are some people that would do this editing line by line because the design is simple.  Now think of a complex shape and what scaling it up or down would entail.This would include changes to the G-Code and reviewing it line by line.  We are talking thousands of lines here vs. going back and quickly scaling the model and spitting out some new G-Code.  And that is why G-Code is throwaway.  Use it over and over when you can, but don’t fret over archiving it if something changes.  It is much better to make a copy of the design (CAD File) in its original state and save that somewhere.  That is much more useful.

Post Processing??? - Now you have me worried.  With all the variations in G-Codes and M-Codes, how will I ever keep it straight?

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