Overview of cutting operations and common settings
Most of Fusion’s cutting operations are organized in a common way, with settings broken into five thematic groups.* Once you get the hang of how the settings are organized, your knowledge will transfer easily across operations.
See the related video here:
Tool
The tool tab is where you select a bit and set your speeds and feeds. If you have already created a custom tool library with appropriate feeds and speeds like I told you to do, then you will breeze through this tab. Just choose your cutting tool and move on.
Geometry
The geometry tab is where you select the features of the model that want to machine, generally faces or contours.
The other options on this tab are less commonly used, and probably won’t come into play for you very often.
So far, CAM is easy: choose a tool and choose the features to machine.
Heights
The heights tab allows you to set the Z level of several machining operations. Much of the time, the default values provided are fine, in which case you can skip right past this tab. Occasionally, however, it is critical that you modify the values here, so it is worth understanding what they mean.
- Clearance height. This is the height the tool moves to when it quickly moves to the start of the next tool path.
- Retract height. This is the height the tool pulls back to in between subsequent cutting passes.
- Top height. This is the height at which Fusion expects to begin cutting. The tool will move at the cutting feed rate once it reaches the top height.
- Bottom height. This is the bottom of the cut.
Each height is specified as an offset from a list of reference heights. For example, the default retract height is 0.2" from the top of the stock, meaning that the tool will pull back 2/10 of inch above the stock in between every cutting pass.
The truth is, you rarely need to modify the first three heights. But the bottom height is important when you want to cut all the through your material. In such cases, you can use a negative offset value to make sure the tool extends a little past the bottom of your stock. More on this later.
Passes
The passes tab allows you to adjust the speed and quality of your cut — which typically represent a tradeoff. Higher speed, lower quality. On this tab you specify tool path parameters such as stepover and stepdown, you indicate whether you want roughing and finishing passes, etc.
Of course, more than just time and quality are at stake. If you’re too aggressive with your cuts, you’ll break a bit. The settings on this tab are important, and you will edit them frequently.
For the direction setting, I generally choose conventional milling over the default climb milling, because I’ve read that climb milling leaves a better finish. But really I should run the experiment myself sometime.
Also, one of the options on this tab is “Smoothing.” I pretty much always check this, because Autodesk claims it is a Good Thing. So far it doesn’t seem to be hurting anything.
Linking
The linking tab describes how the tool moves in between cutting operations. You generally don’t need to touch the options on this tab, except in a few troubleshooting scenarios described elsewhere.
In summary
The main thing to take away from this overview is that in most cases, CAM is pretty easy. Choose a tool. Choose features to machine. If necessary, adjust a few quality settings. That’s it.
Yes, there are dozens of settings to play with, but most of them don’t matter most of the time. And once you get the hang of the basics, even the more obscure settings are much more readily comprehensible.
*Well, all the operations other than drilling, but I suppose that is technically more of a 1D operation.
