CAM basics — before you start

A couple of tweaks to your environment may save you some time and headaches down the road. These are entirely optional and almost certainly reflect my personal preference. So take or leave as you see fit. You can get this same information in video form here:

CAM - before you being | Fusion 360 | Autodesk Knowledge Network

Set Z to up

On your CNC machine, most likely the Z axis is the vertical axis. So make it that way in Fusion too.

1. Click on your name in the upper right, and then click on Preferences.
2. On the “General” tab, change the default modeling orientation from “Y up” to “Z up.”

Turn on your cloud libraries

Autodesk has put a fair amount of effort into cloudifying Fusion, and some of these features are actually pretty handy. This is particularly the case if you use one computer for design and another as the controller for your CNC machine. Rather than dragging files from one computer to the other, let Fusion sync everything for you.

1. Click on your name in the upper right, and then click on Preferences.
2. On the “CAM” tab, check “Enable Cloud Libraries.”

Set up your bits

Of all the suggestions in this article, this is the one that will save you the most time. Setting up your own bits allows you to choose defaults for feeds and speeds. In all likelihood you will rarely vary from these defaults, so configuring your tool library saves you a lot of typing down the line — as well as the headache that comes from a mistyped feedrate.

1. In the main toolbar, click Manage and then select Tool library.
2. In the sidebar, select “Cloud.”
3. Select the “New Tool Library” icon.
4. Name your new library.
5. Select the “New Mill Tool” icon.
6. Fill out the relevant fields and save your new tool.

Many of the fields associated with a tool may not be relevant. Feel free to ignore them. The following are certainly worth paying attention to:

1. Type. You need to tell Fusion the shape of the bit.
2. Number of flutes. Fusion uses this value to calculate chipload.
3. Description. this is the name Fusion will display when you are selecting tools from your library.
4. Cutting edge diameter. essential for generating toolpaths.
5. Flute length. Not strictly necessary, but if you plan to use an adaptive clearing operations, Fusion will attempt to use as much of the cutting length of the tool as possible. Provide the value here.
6. Feed & Speed. All of the settings on this tab should be filled out. Some of the values are calculated for you — in particular, surface speed and feed per tooth.

I also set the Coolant setting (on the Post Processor tab) to Disabled, because the machine I use doesn’t have a coolant system.

By the way, if you do think you will regularly vary the speeds and feeds for a single bit, you can set up multiple profiles for a single bit as separate tools in your library for ease of selection.

Orienting new models

Every model has a work coordinate system, which is a fancy way of saying an X, Y, and Z axis, as well as an origin point. When you’re designing your model, it doesn’t really matter which end is pointing up, since you can freely rotate it in space.

Nevertheless, when I start a new design, I like to set up the work coordinate system to match my CNC machine. That is, I want my model’s up to match real-life up, my model’s left to match real-life left, etc.

This is somewhat compulsive behavior, because it is trivially easier to choose a new work coordinate system when setting up your CAM operations. But I figure the more I can set up my system to do the right thing by default, the fewer opportunities I will have to make mistakes.

I use a ShopBot, which has a slightly confusing coordinate system. Given the usual orientation of the machine operator (you) to the machine, the origin point appears to be in the lower right, with the X axis running up the right side and the Y axis running right-to-left on the closes edge of the machine, like so:

The origin is in the lower-right, based on the the user’s typical relation to the machine.

To set up the same coordinate system in your model, keep in mind this mnemonic: in Fusion, RGB = XYZ. That is, the red axis is X, the green axis is Y, and the blue axis is Z.

1. Create a new model.
2. Create your first sketch.
3. Select the red-green (X-Y) plane for the sketch.
4. Rotate the view counter-clockwise 90 degrees, so that X runs up-down, and Y runs left-right.
5. Create your sketch in the upper-left quadrant, so that they origin point is in the lower right.

It ends up looking like this:

X (red) is running up the right, Y (green) is running across the bottom, and the origin point is in the lower-right, just like my CNC machine.