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CAM Software Guide: Convert 3D Models to CNC G-Code

Q: What is a post-processor in CAM?

A post-processor is a translation script in CAM software that converts generic toolpath data into G-Code formatted for a specific machine controller (Fanuc, Haas, Siemens 840D, GRBL, etc.). Different controllers use slightly different G-Code dialects, so selecting the correct post-processor is essential for the output to run correctly on your machine.

What CAM software does, how it generates G-Code, and which CAM tool is right for your workflow — from hobbyist to professional production. Updated May 2026.

Quick Answer: CAM (Computer-Aided Manufacturing) software takes your 3D model and generates G-Code toolpaths for CNC machines. Popular options: Fusion 360 CAM (free personal license), Mastercam (professional standard), FreeCAD Path (open-source), and HSMWorks (SolidWorks integrated).

What Does CAM Software Do?

CAM software bridges the gap between a 3D model and a running CNC machine. It takes your design geometry and computes the exact path a cutting tool must follow to produce that shape from raw stock material — calculating depths, step-overs, entry moves, tool changes, and feeds/speeds — then outputs this as G-Code for your specific controller.

The CAM workflow has four stages:

Import model — STEP, IGES, or STL file from CAD
Define setup — stock size, WCS origin, machine selection
Create toolpaths — roughing, finishing, drilling, contouring
Post-process — translate to machine-specific G-Code dialect

CAM Software Comparison

Software	Best For	Axes	Cost	Skill Level
Fusion 360 CAM	Hobbyists, startups, general milling	2.5D, 3, 4, 5-axis	Free personal / $545/yr	Beginner–Advanced
Mastercam	Production shops, complex multi-axis	Up to 5-axis simultaneous	~$5,000/yr	Advanced
Solidworks CAM	SolidWorks users, feature-based machining	2.5D–3-axis standard	Included with premium SW	Intermediate
FreeCAD Path	Open-source, hobbyists, simple 2.5D	2.5D, basic 3-axis	Free	Intermediate
HSMWorks	Same engine as Fusion 360, SolidWorks plugin	Up to 5-axis	Subscription	Intermediate–Advanced
VCarve / Aspire	CNC routing, woodwork, signage	2.5D, V-carving	$699–$1,995 one-time	Beginner–Intermediate

Toolpath Strategies Explained

2D Contour: Cuts along the outline of a 2D profile. Used for pockets, slots, and part profiles.
2D Pocket: Removes all material inside a closed boundary. Multiple passes at increasing depths.
Adaptive Clearing (Trochoidal): High-efficiency 3D roughing. Maintains constant tool engagement for fast material removal with long tool life.
Parallel (Raster): Finishing strategy — parallel passes across a surface. Simple and predictable.
Scallop / Contour: Follows surface contours at a constant step-over. Best for curved surfaces.
Drill cycles: G81 (spot drill), G83 (peck drill), G84 (tap) — automated hole-making.

What is a Post-Processor?

Every CNC controller speaks a slightly different dialect of G-Code. A Fanuc controller uses different arc syntax than a Haas, and GRBL uses different feed units than a Siemens 840D. A post-processor is a translation script (built into your CAM software) that converts the generic toolpath into perfectly formatted G-Code for your specific machine.

Selecting the wrong post-processor is one of the most common causes of crashes on new setups. In Fusion 360, go to Post Process → select your controller type from the library. Major controllers (Fanuc, Haas, Siemens, GRBL, LinuxCNC) are included. Custom post-processors can be written in JavaScript.

Verifying CAM G-Code Output

After post-processing, always verify the G-Code before running it on the machine. Drop your output file into GCodex to visualize every toolpath in 3D. Check for:

Rapid moves (G0) that descend into the stock unexpectedly
Tool paths outside the expected work area
Missing retracts between features
Correct spindle direction (M3 vs M4)
Correct coolant commands (M8/M9)

Verify your CAM G-Code output in GCodex — free, browser-based, no upload.

Open G-Code Viewer →

Frequently Asked Questions

What is CAM software?

CAM (Computer-Aided Manufacturing) software converts 3D models into G-Code toolpaths for CNC machines. It calculates cutting paths, feeds, speeds, and tool changes, then post-processes the output for your specific machine controller.

Is Fusion 360 CAM free?

Fusion 360 offers a free Personal Use license for hobbyists and individuals. It includes 2.5D milling, turning, and basic 3-axis machining. Paid subscriptions (~$545/year) unlock 4 and 5-axis simultaneous machining, nesting, and simulation.

What is a post-processor in CAM?

A post-processor translates CAM toolpaths into G-Code formatted for your specific controller (Fanuc, Haas, Siemens, GRBL, etc.). Selecting the correct post-processor is essential — wrong post = wrong G-Code dialect = potential crash.