CAD and CAM are two different jobs
Short answer
CAD is where you draw or import the shape. CAM is where you tell software which bit you are using, how deep, how fast, and what kind of cut. Some programs do both, some do one. Knowing which stage a problem belongs to is most of solving it.
The split
CAD
Computer aided design. What shape do I want?
CAM
Computer aided manufacturing. How does a machine make that shape?
Post processor
Translation into the dialect your controller speaks
Control
The software or controller that actually runs the file
Why the distinction is worth holding onto
When something goes wrong, the first useful question is which stage it belongs to:
| Problem | Stage |
|---|---|
| The shape is wrong, or the letters are misspelled | CAD |
| Rounded corners where you wanted sharp ones | CAD, usually, or a tool geometry limit |
| The part is the wrong size by exactly a bit diameter | CAM: the profile offset |
| It burns, chatters or breaks bits | CAM: feeds, speeds and depths |
| Toolpaths run in the wrong order | CAM |
| The machine ignores tool changes, or plunges at rapid speed | Post processor |
| The job runs in the wrong units | Post processor or CAM setup |
| The machine loses position or stalls | Machine, not software. See lost steps. |
Combined versus separate
| Combined CAD and CAM | Separate tools | |
|---|---|---|
| Workflow | Draw and toolpath in one place | Design in one, import into another |
| Strength | Fast, fewer file handoffs, a change updates the toolpath | Use the best drawing tool for the job |
| Weakness | The drawing tools are rarely as good as a dedicated one | Every design change means re-importing |
| Suits | Most hobby CNC work | Complex design work, or a design tool you already know well |
Plenty of people design lettering and logos in a vector drawing program, then bring them into a CAM package to cut. That is a perfectly good workflow, and it is why file formats matter.
The workflow, end to end
- Draw or import. Get the geometry right and at the correct real world size.
- Clean the vectors. Closed, no duplicates, no excess nodes. See vector troubleshooting.
- Define the material. Thickness, where zero sits, and where the origin is.
- Define the tools. Real measured diameters, and the feeds and speeds you intend to use.
- Create toolpaths in the order they will run.
- Preview and simulate. Two minutes that saves workpieces.
- Post with the right post processor for your controller.
- Set up the machine and run it.
The step people skip
Simulation. Every serious CAM package has it, and it catches rapid moves crossing clamps, cuts deeper than the material, toolpaths in the wrong order and profiles running off the stock. It costs two minutes.