Brief History & Explanation of CNC & G-Code

Download the worksheet here
Either download the word document above, and type the answers in and hand in to your instructor, or follow the directions below.

If you look it up the definition will be something like this: Gcode is a language in which people tell computerized machine tools how to make something. If you are interested in cnc machining, Free CNC Training Courses are usually offered online. Read more below to learn more about CNC.

Step 1: A Little CNC History: Read an article and answer the questions

Standard Gcode was originally used in the MIT Servomechanisms Laboratory in 1958, and was later standardized by the Electronic Industry Alliance. Computer-aided design (CAD) emerged during the ’60s to give designers the opportunity to visualize their creations before a physical prototype was available. For more info about this go to Tormach’s blog to get a bit of history on CNC. Click on the picture below to go to the article as well.

After reading the article, copy and paste the questions below into a google doc, an LMS, or a Word doc, and hand them in to your instructor.

  1. What does CNC stand for?
  2. Around what time did CNC first become popular?
  3. Where was G code first developed for use with milling machines?
  4. What are some advantages of CNC over manual machining?
  5. Going Beyond: What is the difference between a CNC Lathe and a CNC Mill? Find a picture of each on the internet, paste them into the document here, and explain in your own words.

Step 2: An Introduction to G-code and CNC Programming Read an article and answer the questions

So to make CNC machines work, you have to be able to communicate with them. The method by which we do this is called G Code. G-code is the operational language for CNC machining. It tells numerically controlled lathes and machining centers how to move tools in order to perform various cutting operations. It is equivalent to manual programming where each operation is spelled out line-by-line and is separate from M-code and T-code, codes that control the machine and tooling. G-code fits somewhere between conversational control, where the operator describes the part and how it should be machined, and CAM, or computer-aided manufacturing, programs, where software develops the necessary toolpaths, feed rates, and so on needed for the CNC machine to cut the material into the finished part. Click on the link below to read the article about how G code programming for CNC machines is done then answer the questions!

After reading the article, copy and paste the questions below into a google doc, an LMS, or a Word doc, and hand them in to your instructor.

  1. What coordinate system does a CNC machine use? Where have you heard of this before?
  2. What does the “G” in G code signify? Be sure to give an example.
  3. What does the “M” in M code stand for? Be sure to give an example.
  4. Approximately how many G codes are there when programming a CNC machine?
  5. Going beyond: Find the link in the article where you would find a list of common G codes, click on it and make a chart that tells what the following G codes do: G00, G01, G02, G03, G20, G21, G54, and G73

Step 3: What are G codes and how do they work? Watch a video and answer the questions

Watch the video above then copy and paste the questions below into a google doc, an LMS, or a Word doc, and hand them in to your teacher.

  1. What type of CNC machine is that behind Mark in the video? Why did you choose that answer?
  2. Who was the first person to mount a motor onto a hand wheel of a lathe or milling machine, and what type of motor was it? Be sure to answer both questions.
  3. What do M codes do, simply put? Be sure to give an example.
  4. What are DHT Codes?
  5. What are Feeds & Speeds?
  6. Why are there G code groups? Give an example in your answer.
  7. In Mark’s example of a drilling operation, what tool number did he use, and what was the spindle speed in RPM’s?
  8. What was the Programmed Feed rate in Inches per minute (IPM)?

Step 4: Going Beyond

Going beyond: Using your incredible internet search capabilities and what you have just learned, answer the following three questions. Just copy and paste the questions below into a google doc, an LMS, or a Word doc, and hand them in to your teacher:

Hint: Start at about 4:00 of the video from step 4!

  1. What code would Mark use if he wanted to use inches in his program, and not the metric system?
  2. What does an M06 do in Mark’s program?
  3. What does M03 S2500 mean in Mark’s program?

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Robocell: Palletize and Storage


How do I do Robocell Activity G, Palletization & Storage? That’s hard!


It’s not that hard to do once you understand the concepts behind variables.


Here are some video tutorials to get you on your way:

Palletize & Storage: Concepts & Cell

Palletize & Storage: Programming the Cell


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How do I get G&M Code Using Inventor HSM?


How do I get G&M code from Inventor HSM to make my actual part on the milling machine?


reddownload post-code-with-hsm

It’s really gotten very easy to do with HSM. Follow the directions below, and you should be all set!  Be sure to download the PLTW tool library, and watch video 0 at the link below so that when you verify it in CNCmotion, it will work. This link shows you how to install the post and tool store, and provides a link below Video 0 to download the toolstore and post for the Intellitek machines: HERE



Step 1


Click on the Post Process tool in the toolbar as shown above.

Step 2 Choose the type of machine you have. In this case I am using an Intellitek mill.
Step 3 Chose where you want it to save the NC file.
Step 4 Click on the Post button at the bottom. Your code will then open in a code editor, and be saved in the folder where you told it to be. You should now be able to open it in CNCmotion and simulate it or run the code on the machine of your choice!





















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How do I make an arc using G & M codes?



It’s easy! The method shown here shows you how to do it with a known end point and centerpoint. The four minute video below shows you how step by step.

Sorry for the poor sound quality, but it’s real time during a lesson in class with a students example!

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Is There A Better Way To Teach G & M Coding By Hand?


Initials on a wax block are boring and expensive!  Do you have a better way to teach G & M code basics?


Sure do!  How about doing initials, or a simple graphic on a wooden yo-yo?  That’s right, a yo-yo. Students love it!

Special thanks to Chris Lallier who put it all together with the help of Jim Hanson and myself.  Also, a very special thanks to Chuck “The Godfather of CIM” Spangler, who has been doing plastic yo-yo’s for many years!

All you need to do is download the zip file below, and order the Yo-yo kits WITH sleeper string; that’s right, a SLEEPER string, and you are off to the races.  Yo-yo’s are about $1.50 each; much cheaper than wax or Renshape, and kids can do “testing” on the product after it is finished and assembled. A great all around project.  You will however have to build the fixture to hold the yo-yo’s

The yo-yo blanks can be bought at Casey’s Wood in Maine, and they do take PO’s.  Tell them Chris & Jim sent you!


reddownloadYo-Yo Files

In this file you will find all of the information and files that you need to build a Yo-Yo holding fixture.  This fixture is designed to firmly hold wooden Yo-Yo halves while they are engraved with a CNC Machine.

Includes the following documentation:

FILE 1a. YO-YO Fixture step-by-step
FILE 1b. Pdf. YO-YO Fixture step-by-step
FILE 2a. YO-YO Fixture Autodesk Inventor Drawing
FILE 2b. Pdf. YO-YO Fixture Autodesk Inventor Drawing
FILE 3. YO-YO Fixture Autodesk Inventor Part File
FILE 4. YO-YO Fixture EDGECAM File
FILE 5. YO-YO Fixture NC File
FILE 6. Grid Paper File
FILE 7. Technical Support
FILE 8. Credits

WP_0005231Technology teacher Chris Lallier from SUNY Oswego has put together a killer project for teaching basic CNC programming. The project consists of a wooden yo-yo that is engraved, using CNC, on both sides. Students are then able to paint, stain, sand and assemble the project, giving students the opportunity to learn about more manufacturing processes.

Special thanks to Chris Lallier who put it all together with the help of Jim Hanson and myself.  Also, a very special thanks to Chuck “The Godfather of CIM” Spangler, who has been doing plastic yo-yo’s for many years!

YoYo_PartsThe Yo-Yo kits, unassembled, are available at Casey€™s Wood Products, and cost less than a dollar each if you order 50 or more. The best part is that this is the DELUXE model: with a sleeper string! It was the only place that sold them in smaller lots, and you can buy them individually as well. We looked into plastic ones as well, but they had to be purchased in lots of 250. This would make a great promo for open house as well!

YoYo_Fixture_FinalThe project consists of a teacher built fixture to hold the halves in your machine, and then provides you, the teacher, with a student driven activity to produce the final product. Also included is a step by step guide on building the fixture, a complete parts list, the Inventor, EdgeCAM, and NC files, as well as student templates.

The whole project, including all the above files, is available in the downloads section for your use. The file is a .zip file, and just needs to be downloaded, and unzipped, in order for you to use the files.

Chris Lallier is a Student Teacher from SUNY Oswego graduating in December 2011. He is a Technology Education major with a background in residential construction. While working summers with his family construction business he was introduced to CAD home building programs, structural design, manufacturing processes and planning techniques. He was inspired to move into the field of Technology Education so that he could teach others about the topics that he found fascinating. He is currently teaching three college credit courses at Cazenovia High School; Principles of Engineering, Design and Drawing For Production and Computer Integrated Manufacturing. Chris is looking forward to a long and rewarding career of learning and teaching students about all things Technology.

Click HERE to Download!

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