Fusion 360 CAM for Beginners: Setting Up Your First Milling Toolpaths
Computer-aided manufacturing — CAM — is the process of using software to plan and generate the instructions that CNC machine tools need to cut a part from raw stock. For anyone who designs in 3D CAD and also needs to machine parts, having CAM software integrated into the same environment as the design is a genuine advantage. You do not need to export, import, or maintain two separate files — the toolpaths update when the design changes, and the same model that was designed is the one being machined.
Fusion 360 includes a full-featured CAM environment, and it is one of the key reasons the software has attracted such a large following among small machine shops, product designers, and hobbyist machinists. This guide is aimed at users who are comfortable in Fusion 360’s design workspace and are ready to take their first steps into the CAM environment.
Understanding How CNC Milling Works
Before setting up any toolpaths, it helps to understand what a CNC milling machine actually does. A vertical machining centre (VMC) — the most common type of CNC milling machine — has a rotating spindle that holds a cutting tool, and a work table that moves in three linear axes (X, Y, and Z). The machine controls tool-to-workpiece contact to remove material precisely. More sophisticated machines add a fourth axis (typically rotation around X or Y) or a fifth axis (typically simultaneous tilting), enabling complex undercut features to be machined without manual repositioning.
The instructions that drive the machine are called G-code — a text-based format containing movement commands (G00 for rapid positioning, G01 for linear cutting moves, G02/G03 for arcs), spindle commands (S for speed, M03/M04 for direction), and tool change commands (T and M06). CAM software generates this G-code automatically based on your model geometry and the machining strategies you configure.
Setting Up the CAM Workspace in Fusion 360
Switch to the CAM workspace using the workspace dropdown at the top left of the Fusion 360 interface. You will see the dedicated Manufacturing toolbar replace the design tools. The workflow in the CAM environment follows a consistent structure:
- Create a Setup (define the stock and work coordinate system)
- Create Operations (define the individual cutting toolpaths)
- Simulate and verify the toolpaths
- Post-process to generate G-code
Creating a Setup
The Setup is the foundation of your CAM programme. It defines three essential things: the orientation of your part on the machine table, the location of the work coordinate system (WCS), and the size and shape of the raw stock material you are starting from.
Work Coordinate System
Click Setup in the CAM toolbar and the Setup dialogue will open. The WCS defines the origin that all your toolpath coordinates will be measured from. By convention, the Z axis points up (out of the work surface), X points to the right, and Y points towards the back of the machine — though many machines can work in any orientation.
You need to position the WCS origin at a point that you can locate precisely on the real machine: typically the top corner of the stock, the top centre, or a machined datum surface. Using the top corner of the stock (particularly the top-left-front corner) is common for prismatic parts because it allows you to use simple edge-finding operations to set the work offset on the machine.
Stock Definition
The stock represents the raw material before machining. Fusion 360 lets you define stock as a box (with selectable oversize on each face relative to the model bounding box), a cylinder, or a custom shape from another body in your model. For most milled parts, a rectangular box stock is appropriate. Setting small oversize values (0.5 mm to 2 mm per face) is realistic and helps the CAM simulation show the initial material removal correctly.
Building Your Tool Library
Before creating any operations, you need to define the cutting tools you plan to use. Fusion 360 has a built-in tool library that can be populated with your actual tooling. Open the Tool Library by clicking Tool Library in the toolbar.
For a basic milling setup, you will typically need at minimum:
- A flat end mill for roughing and profile operations (common sizes: 10 mm, 12 mm, 16 mm)
- A smaller flat end mill for finishing floor faces and pockets
- A ball end mill for 3D contour finishing of curved surfaces
- A spot drill for starting hole operations accurately
- Twist drills in the diameters you need
For each tool, you define the geometry (diameter, flute length, overall length, shank diameter, corner radius) and the cutting data (speeds and feeds). Getting speeds and feeds right is critical: too slow and you get poor surface finish and built-up edge on the tool; too fast and you risk tool breakage. Speeds and feeds depend on tool diameter, material being cut, tool material (carbide vs HSS), and cut depth and width. Manufacturer data sheets and online calculators (such as those provided by tooling suppliers) are your starting point.
Creating Milling Operations
2D Adaptive Clearing (Roughing)
For most prismatic parts — those with predominantly flat faces, vertical walls, and horizontal pockets — the first operation is a 2D adaptive clearing pass to rough out the main features. This strategy uses a trochoidal (circular arc) cutting motion to maintain a consistent chip load and maximise material removal rate. Click 2D in the toolbar and select Adaptive Clearing.
In the Geometry tab, select the contours or faces that define the region to be cleared. In the Passes tab, set your optimal load (the radial depth of cut as a percentage of tool diameter — typically 20-50% for carbide end mills in aluminium) and your axial depth (the depth per pass — for full-flute engagement, start at 1× diameter). In the Heights tab, define where the toolpath starts (stock top) and where it finishes (pocket bottom).
The adaptive clearing strategy is highly recommended for roughing because it maintains consistent tool engagement, reduces peak cutting forces, and allows significantly higher feed rates than conventional pocketing strategies. The toolpaths look unusual — lots of arc moves rather than straight lines — but they are very effective.
2D Contour (Profile Cutting)
Once pockets and internal features are roughed, a 2D Contour operation machines the outside profile and any vertical walls. Select 2D Contour, choose the chain of edges that defines your profile, and set the cut depths. For thin parts, you may be able to do this in one pass; for thicker stock, multiple passes at increasing depths (depth of cut per pass) are needed.
Pay attention to the entry move settings. For profile operations, a tangential arc entry (where the tool curves smoothly into the cut) produces much better surface finish and is gentler on the tool than a direct plunge into the material.
2D Pocket
Use the pocket operation for rectangular or irregular enclosed pockets. After roughing with adaptive clearing, a separate 2D pocket operation using a smaller tool can finish the pocket floor and step down to final depth with a light finishing pass. Set a small radial stock leave (0.1-0.2 mm) on the roughing pass and machine to finished size on the final pass.
Drilling
Fusion 360 supports a full range of drilling cycles: spot drilling, drilling, peck drilling (for deep holes), reaming, boring, and tapping. Select Drilling from the 2D menu, choose your drill from the library, and select the hole faces or circles. Fusion 360 will automatically detect all matching holes if you choose a face from a pattern. Set your peck depth increment for deep holes — typically 2-3× the drill diameter per peck to clear chips effectively.
3D Contour Finishing
For parts with curved or sculpted surfaces, 3D operations are needed. The most commonly used 3D finishing strategies in Fusion 360 are:
- Scallop — creates parallel passes across the surface at a constant scallop height (step-over). Good for shallow to moderate curvature.
- Contour (3D) — generates passes that follow the z-height contours of the surface. Good for steep walls.
- Parallel — simple parallel passes in a specified direction. Good for gentle single-curvature surfaces.
- Pencil — traces concave corners and blend radii that other strategies may miss. Often used as a cleanup pass after scallop.
3D finishing operations use a ball end mill to trace the surface, leaving a very small remaining scallop between each pass. The size of this scallop (and therefore the surface finish) is controlled by the step-over distance — smaller step-over gives better finish but longer machining time.
Toolpath Simulation
Before generating any G-code, always simulate your toolpaths. Click Simulate in the Actions section of the CAM toolbar. The simulation shows the material being removed in real time, with the tool shown moving through the toolpaths. Watch carefully for:
- Gouges — where the tool cuts into material that should be left (shown in red)
- Rapid collisions — where the tool is in a rapid traverse position that would collide with the stock or fixtures
- Missed regions — where the toolpaths do not cover some of the intended geometry
- Holder collisions — where the tool holder itself would contact the workpiece
Fusion 360’s simulation can display the remaining stock after each operation, making it easy to spot missed regions. The simulation can also display tool holder geometry if you have defined it in your tool library, enabling holder collision checking.
Post-Processing to G-Code
Once you are satisfied with the simulation, you need to post-process — convert Fusion 360’s generic toolpath data into machine-specific G-code. Click Post Process in the Actions menu. You will need to select a post processor that matches your specific CNC controller. Fusion 360 includes post processors for most common controllers including Fanuc, Siemens Sinumerik, Heidenhain, Haas, Mazak, and many others. If your machine uses a controller not listed, the Autodesk post library at cam.autodesk.com contains a very large selection of additional posts.
After post-processing, you have a .nc or .tap file (the extension varies by controller) ready to transfer to the machine. Review the G-code with a text editor or a dedicated G-code viewer before running it — a quick scan through the code to check that tool changes, spindle speeds, and coolant commands look correct is worthwhile insurance.
A Note on Speeds, Feeds, and Material
Generating a valid toolpath is only part of the job. Speeds and feeds that are correct for aluminium will likely break a tool in steel; feeds that are fine for roughing with a large end mill will cause vibration and poor finish with a small ball nose cutter. If you are new to machining, the most important thing you can do is start conservatively — slower feeds, shallower cuts — and increase aggressively once you have confidence in how the material and tool are behaving.
Most tooling manufacturers publish recommended starting parameters for their tools in various materials. Sandvik Coromant, Seco, and Kennametal all have online calculators that will generate speeds and feeds for their specific tools based on your material and cut parameters. Using manufacturer-recommended values as your starting point and adjusting based on what you observe on the machine is a sound approach.
Getting Started with Fusion 360 CAM
The CAM workspace is fully included in Fusion 360, with no additional purchase required. Fusion 360 is available from GetRenewedTech at £39.99, making it an extremely cost-effective entry point for anyone running a small machine shop or looking to integrate CAM into a product design workflow. The combination of integrated design and CAM in a single model file significantly reduces the overhead of managing design iterations through to machining.
Conclusion
Fusion 360’s CAM environment provides a comprehensive set of 2D and 3D machining strategies within the same software package used for design. Setting up your first milling programme is a learning process, but the structured workflow — setup, operations, simulation, post-processing — provides a clear path from model to machine. Start with simple 2D parts, build confidence with the adaptive clearing and contour strategies, then gradually incorporate 3D operations as your understanding of feeds, speeds, and tool behaviour grows.
