Deliverable: Loaded the best file format for your CAM software. Ready to start programming in CAM.

If you're using CAM software that's integrated with your CAD package, the designers of the CAM have already made sure the two are talking well together. But if you have separate packages, you want to make sure you use the best file format when you load your CAD model into the CAM package. See our article below for help on the best file formats:

Resources:

- Demystifying CAD File Formats

Deliverable: Each feature programmed and ready to post so we can get g-code.

This page drills down into our article, "Secrets of CAM for Beginners." It's a good introduction because it takes you step by step through using two different CAM packages to generate part programs for the same simple part. This will help you to understand what's going on when we talk about using CAM software to do CNC programming.

Both packages are pretty simple and low-end. There are much more complex packages out there. In general, most CAM packages require you to know a fair bit about machining to use them. You will be going over each feature of the part in your CAD model and answering a whole bunch of questions for the CAM software about how you want to machine the feature.

Many of the questions are going to be hard for a beginner to answer without some experience and knowledge to go on:

- What kind of toolpath should you use? You'll need to understand the basic choices such as pockets, 2D profiles, 3D profiles, and more.

- What method do you want to use to enter and exit the toolpath? Plunge, ramp, and helix to name but a few. What are their strengths and weaknesses? Why would you choose one over the other?

- Which tool do you want to use to cut the feature?

- What Cut Width (also called Stepover) and Cut Depth (how many levels or Step Downs) do you want to use?

- What Feeds and Speeds should be used?

- etc..

Most beginners think that CAM is simple--you just load the CAD model, push a button, and out comes the g-code. Unfortunately, having to make all those choices makes most CAM software far from simple for beginners.

My advice to many starting out is to plan on using more than one CAM package. Start with the simplest possible package. We recommend and even sell MeshCAM because it comes closest to that idea of push a button and out comes g-code than any other package I've seen. It's super simple but powerful enough to make complex parts. You'll be making parts a lot sooner and without the steep learning curve as a result.

Eventually, when you've learned a lot more, you will wind up wanting a more powerful CAM package. That's fine--you will have gotten a ton of use out of MeshCAM and it's very inexpensive. I still use it from time to time when I have something simple to do. It's just faster and less cumbersome.

Here are a variety of resources to help you when trying to answer the many questions CAM software will throw at you:

Resources:

- 2 Tools for Calculating Cut Dpeth and Cut Width When Milling: These two questions are important to answer, and these 2 tools give you easy systematic help in answering them. They will help you a lot!

- Toolpath Considerations: How to enter and exit a toolpath? This article covers that. What to do about Feeds and Speeds for CAM? Ditto.

- 7 Software Excuses for Bad Surface Finishes: Goes into some of the choices you'll be making for the CAM software and their impact on surface finish.

Consider these articles required reading if you're a Beginner. They will fill in many of the blanks that are giving you a headache when you sit down to try to use your CAM software.

Deliverable: G-Code part program.

There are Many Dialects of GCode...

Okay, you got through the giant mass of questions your CAM software kept asking and you're ready to get back your g-code. The process of generating g-code in CAM software is called "Posting." We describe posting in the Digital Tooling article referenced at the top of this page.

Running the post is usually a simple command that requires little explanation. But getting set up to post can be more problematic. It requires you to find or configure a Postprocessor that tells the CAM Software is required for your machine's g-code dialect.

If you're lucky, your CNC Machine is a popular model and someone else already created a nice Postprocessor that's available for you to use. Always check first as creating your own can be a real pain.

Here are some resources to help you get more acquainted with Post Processors:

Resources:

- Introduction to G-Code Dialects and Post Processors.

- The Ugly Secret About Post Processors Plus 8 Custom Post Processor Ideas

Deliverable: Partially proven G-Code Part Program.

Many CAM programs have a builtin simulator. Go ahead and run it to see what you can learn about whether your part program is going to behave as you'd hoped. Just be aware that these simulators are almost never true G-Code Simulators such as we described in the Simulation section of this series. As such, they will let a lot of problems come through even though the simulation looks perfect. You need a true G-Code Simulator to do real simulation to cut down on the need to Proof your G-Code.

Deliverable: Improved G-Code Part Program.

Most of the time, we run CAM-generated g-code without further modification. But for those CNC'ers who are capable, many powerful things are possible if we can hand modify the CAM program to make it better. Judicious use of hand coding can make a CAM generated program faster and far more flexible.

Resources:

- 37 Things Your CAM Won't Do For You That GCode Programming Can: A list of ideas for what you might do by combining CAM and hand coding.