Technology Information

cnc programming

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.G-Code and CNC programs 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 would not.  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 gcode.

There are people lead do this editing line by line because their design is very 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 changing the size of the model, then creating 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?

Don’t worry about that.  The CAM program you choose will have many Post Processors.  Post Processors are like translators.  They help the CAM Program spit out the right CNC Program for your specific machine.What you have to do is select the right post processor before you create the G-Code.  That is simple.

Most CAM programs have many machine specific post processors already loaded.  All you do is go to the list of them and click on your machine to select it.  If you build your own CNC Machine, there are generic post processors loaded for different types of machines.  Usually you pick a generic one and modify it a bit with a little testing.  You are making sure a move in the X-Axis positive direction really means what you want it to mean.

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cnc programming

Any subject that covers working in the shop should begin with safety.Yours and other people safety should be at the top of your mind.CNC is not different than any other shop topic that you will encounter.  In fact, the highest levels of safety awareness should be maintained when using a CNC machine.

CNC machines don’t have a mind of their own.  A computer gives them a command and they execute it.Machines don’t care if they are cutting steel, wood or your hand.  They don’t differentiate between materials.  You need to be aware of this.

When you are Studying CNC you should take it slow.  Do tests on a small scale, then watch and learn what happens.  For example, why don’t you let your machine “cut air” for a while when you first get it.  You don’t need to put it right to work cutting material.  Why not create a simple program, and let the machine cut the air instead of material.  Better yet, why even run the spindle during the test.

Every CNC Machine has quirks that you need to learn.Every CNC machine has a different working window.  Every CNC machine is just a little bit different then the rest of them.  It is in your best interest to learn your machine before you put it to work.

Generally, with a CNC Machine, we are machining something.  While machining, “chips” are being thrown off.  Sometimes at a very rapid speed.  Here is where safety glasses, face shields and material barriers come into play.  Use them!  The machine doesn’t know you are standing there.  In the words of every boxing ref before a match, “protect yourself at all times!”

A few ideas to keep you safe in the shop:
Always read the instruction manual before using your machine
Always follow manufacturers recommendations
Always wear safety glasses
You need to wear the appropriate safety equipment for your job
Use shields and barriers while machining when it is appropriate
Checkout and test your machine before running parts are going into production
Perform proper and routine maintenance on your machines
Perform checks on your machine for wear and damage

Always think safety!

CNC site with free information:
If you would like to know more about CNC, head on over to http://www.cncinformation.com
You can join for Free and you get two free CNC ebooks. One is a GCode Quick Guide and the other is the CNC Info Site eBook. You also get access to the Free Video Series…Image to CNC Art when you join the community.

cnc overview

Rapid overview of the CNC process
This is how I view Computer Numerical Control.I break it down into steps that I can remember easily.  Now, they all interact, but it is good to keep them in boxes for simplicity sake.  I also like to keep them in a logical, progression type order.  Here they are: Design, CAD, CAM, Control and Machine.

Today you are going on a journey.  You are going to learn about the basics of CNC.I trust you are as excited as I am about this subject.

I have been using CNC equipment in my home shop for six years now.The CNC technology gets better all the time.  The software gets better every year.  At one time large companies could only afford this technology.There are CNC machines by the thousands working in garages like yours and mine everywhere.

There are basically five elements to a CNC Project that you need to know:
Design - planning on what you want to build
Computer Aided Design - translating it into the computer
CAM - converting it into machine language
Controlling - controlling your CNC machines movements
Machining - building the part to specifications

These five elements are really the building blocks to a CNC project.  As you see them above, that is generally the order people associate them in.  For example, you can’t control until you have a design.  You can’t use your CAM software before your CAD software.One of the things you need to take into account is how these different elements interact with one another.
This may cause some confusion right now.  Over time, it will seem very basic.The more you use these CNC elements with one another the more their order will become apparent.

CNC Information Free Community Site:
If you would like to know more about CNC, head on over to http://www.cncinformation.com
You can join for Free and you get two free CNC ebooks. One is a GCode Quick Guide and the other is the CNC Info Site eBook. You also get access to the free CNC video series…Image to CNC Art when you join the community.

G-Code

Machine Controllers take your machining instructions from your G-Code and converts the G-Code into motion.  You are off to the races.  The controller interprets the signal pulses from your Control Computer and instructs the machine to move.

The CNC Machine Controller is made up of various electrical parts.  Remember earlier that I said some electronic junkies flock to CNC.  This is why.  Machine controllers can be built if you are savvy with a soldering iron.  I myself am not.  I personally always default to ordering up a Machine Controller from one of my sources.

Controller builders to me are electronic gods.  They mix power sources, match up Amp, Volts, etc into the item I need.  Generally, you can pick the number of Axis you want before they build the controller.  For example, if you are building a CNC Plasma Cutter you may want a two-axis controller.  Possibly a three-axis controller if you have a Torch Height Control.  If you have a milling machine or a wood router in mind, then a three axis is your ticket.  If you want to machine with a rotary axis, then you need a four-axis controller.  So on and so forth.

Here are some example controller prices
Here are some prices you might see in the marketplace.Most come with motors and cables as well.  Really, you purchase a whole kit at once if you go this route.  The other way to do it is to buy components and assemble it yourself.  I wouldn’t suggest this for the beginner.

Prices
2 Axis – $1000–$3000 - Movement in the X and Y axis, dependent on the size of motors you order
3 Axis – $1500–$4000 - Movement in the X, Y and Z axis, dependent on the size of motors you order
4 Axis – $2000–$6000 - Movement in the X, Y, Z and A axis, dependent on the size of motors you order

Note: The A-axis is the rotational axis.  Why is it called that?  I don’t know.  It is also sometimes called the B-axis.  I have even heard it called the W-axis.  A-axis is the rotational axis around the X-axis. B-axis is the rotational axis around the Y-axis.

Buying a completed CNC Machine
If you purchase a CNC Mill outright, it will have a machine controller as part of the package.  Everyone does it a bit different though.  Some try to make it a black box that only they can fix.Other people use commonly used components so you could repair it if need be.  You will just have to ask the manufacturer and see what they say.  My experience says they usually tell you that it uses common components that you can get anywhere if needed.  If something goes wrong, it seems you can only get the part from them.You are going to have to decide for yourself.

Internal Machine Controller Parts
There are many different components that go into a machine controller.  I won’t pretend that I am an expert on this.  Actually, this is one of the components I buy pre-made so I don’t have to do it.If you are electronics wizard you could build your own.I know my skills and it isn’t assembling and understanding electronics.

Here is what I know about the guts of a controller.  There will be drivers.  One for each axis.  Gecko Drivers seem to be the best value on the market right now with great support.  I have used Gecko drivers in two of my creations and they work great.  Next, is a processor to do the computing work.  A power source to power the controller.  Finally the external cableling that heads out to the motors at each axis on your machine.
There is more to it than that and I probably left out something.  Those are the basic parts of machine controllers.

CNC Control Pendants
I did not know where to put this section.  The Machining Chapter or Machine Controllers Chapter.  It ended up here because the pendant is almost always hooked to the controller.  Any pendant automatically gets a gold star from me.  I love them.  If you use one, I guarantee you will love it.

Pendants are a true lifesaver when machining.  They give you access to commonly used functions about anywhere you want them.  You can jog the machine to a new location.  You can zero out your axis with a click.You can even change your machining speeds while machining.  All pendants are different and are usually associated with a purchased Machine Controller.

Pendants can be made.  There are a number of people out there that have pieced them together.  Generally these are the electronic types of people involved with CNC.  They like this extra challenge.Many of these homemade CNC pendants come out very nice.Many of these people are proud of their designs and will share their plans and component lists with you.The trick is to find them.

Free CNC information community site:
If you would like to know more about CNC, head on over to http://www.cncinformation.com
You can join for Free and you get two free CNC ebooks. One is a G-Code book and the other is the CNC information site book. You also get access to the Free Video Series…Image to CNC Art when you join the community.

CNC Controller

The CNC Controller generally resides in the shop somewhere near the CNC machine it is controlling.  Control Computers don’t have to be the top of the line, every bell and whistle type of computer.These are what do the work.  Save your money for a good design computer.  You will save much more time having a fast computer for your designing.

A control computer doesn’t have to be that powerful for a few good reasons.  It doesn’t have the workload.  It takes G-Code and turns it into signals that it transmits to the Machine Controller.  Turning G-Code into signals is not that labor intensive for a computer.

I have used multiple types of control computers.  Everything from a 486 DOS running “$30 special” to a modern Dell with Windows XP.  I have yet to try one with Vista.  I will keep you posted.  Generally I like to find a good used computer for a couple hundred bucks, wipe the hard drive and only load the control software onto the machine.You know what you have that way.

There is another good reason you don’t want to spend a lot of money here.  This computer will usually be located in the shop.  Dirt will be located in your shop.  Using logic here, dirt will be located in your computer.If the computer happens to fail, you aren’t out of a lot of money.

Here is my strategy in a nutshell for Control Computers.  The dirtier the job, the less money I spend on the computer.  My plasma cutting computers are bought in the $40 range.They suck up a lot of dust and dirt.  I blow them out frequently.my CNC wood routing computers cost about $100.  My milling machine computers usually are in the $200 range.  Truth be told, they all last a very long time if you keep dirt, dust and plasma smoke out of them.

How is the CNC Control Computer used?
The computer has CNC control software loaded on it.  You start up the control software then load up the CNC Program you created.  When you do this, the G-Code will be visible and ready to go.  Once you prep your CNC Router and zero it out, you can begin your “cycle.”  A cycle is usually completing one CNC Program, which is a machining sequence.  You will also hear the term “Cycle Time” on the professional side of CNC a lot more.  The quicker you can get the cycle time, the more parts you can make.  And yes, that translates to more money.

Back in the good old days of DIY CNC, everything was transferred on a disk.  Now I have seen people include their Control Computers on their home computer network and transfer the files needed wirelessly.  At a very minimum, get a good jump drive and transfer things back and forth that way.

CNC Information Free Community Site:
If you would like to know more about CNC, head on over to http://www.cncinformation.com

You can join for Free and you get two free CNC ebooks. One is a GCode Quick Guide and the other is the CNC Info Site eBook. You also get access to the Free Video Series…Image to CNC Art when you join the community.