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1. What is the CNC Workflow?

Here's how a typical desktop CNC job flows from start to finish:

It begins with CAD (Computer-Aided Design) software, where you create 2D or 3D geometry. The CAD environment defines the part’s shape, dimensions, and features. It does not define how the machine cuts; it only defines the final geometry.

Most CAD software supports multiple file formats. For CNC, they fall into two buckets: 2D vectors and 3D models.

2. Phase 1: Design — Working with 2D and 3D Geometry

2D File Formats: DXF vs SVG for CNC Work

2D files are used for contour cutting, pocketing, drilling, and engraving. They contain planar geometric information without thickness or volume.

Short for Drawing Exchange Format, DXF is the industry standard for exchanging engineering drawings.

SVG files describe shapes with mathematical curves (not pixels), so they scale infinitely without losing quality. In CNC, SVG is great for contour cutting, engraving text, and sign making.

Think of it this way: DXF is for engineers (precision, dimensions), SVG is for designers (scalable, artistic). Mechanical work → DXF. Signs, text, art → SVG.

3D Model Formats

When a part includes complex surfaces or 3D structures, 3D formats are required.

Summary: 2D files define outlines and require depth input in CAM. 3D files define the full volume, allowing CAM to calculate paths based on the surface geometry.

3. Phase 2: The Logic Layer — CAM Planning & Strategies

CAM converts your CAD geometry into toolpaths that the machine can follow—the trajectory the tool follows relative to the workpiece coordinate system.

Stock Setup

In CAM, you enter your stock dimensions (X/Y/Z). This sets the virtual cutting boundary. Thickness matters: set it too thin and you won't cut through; set it too thick and you'll cut into your spoilboard. The origin (zero point) is typically at a corner or center — just make sure it matches where you'll set your zero on the actual machine.

Workpiece Origin (Zero Point)

The work coordinate origin is the reference point for all toolpath calculations. Every X, Y, and Z move in the toolpath is relative to this zero point.
Set your workpiece origin here, matching where you positioned it in CAM.

Tooling Parameters

Choosing the correct tool and matching it with technical parameters.

Define diameter, flute length, and type (End mill, Ball nose, V-bit).
Diameter: Determines the tool compensation path and the smallest internal corner radius (e.g., a 6mm tool can't cut a corner tighter than 3mm).

Speeds & Feeds:

Spindle Speed (RPM): Must match the material and tool diameter. Too low causes instability; too high causes excessive wear or heat.
Feed Rate: The horizontal movement speed. Too fast causes tool breakage; too slow causes material burning.

Step-down & Step-over:

Step-down: Layered cutting (e.g., cutting 12mm deep in 4 passes of 3mm each) reduces load and vibration.
Step-over: Lateral distance between passes. Smaller step-over improves finish but increases time.

Leads & Safety:

⚠️ Safe Height: Always set your retract height above your workpiece AND above any clamps — this is the #1 thing beginners get wrong.
Entry Strategy: Ramping or helical entry is preferred over vertical plunging to reduce axial impact.

Machining Strategies

Use this when cutting along the inner or outer boundary of a shape.

Use this when clearing all material inside a closed boundary layer by layer.

Use this when vertical movement at specific points for round holes.

Use this when shallow cutting along the centerline of a path.

4. Phase 3: The Execution Layer

Once the G-code file is generated, transmit it to the CNC controller.
Use a G-code Sender (e.g., gSender, Candle) to transmit the file via USB. Key functions include:

5. Hardware Setup: Clamping & Tool Installation

Tool Installation

Workpiece Clamping

Clamping prevents movement under cutting forces.

6. Coordinate Systems: MCS vs. WCS

7. Formal Machining: Dry Run & Monitoring

Dry Run

Run the full program with the tool raised above the material. This confirms your coordinates are correct — and that the tool won't crash into your clamps.

Starting the Job

Start the spindle and wait for it to reach full RPM. Keep the feed rate override low for the first few passes so you can watch the cut closely.

Appendix: Technical Reference

The Post-Processor

Think of the post-processor as a translator — it converts your CAM toolpaths into the specific G-code dialect your controller speaks (GRBL, Mach3, etc.). Make sure you've selected the right one, or your machine might not understand the instructions.

Common G-code Commands

Summary

A successful desktop CNC workflow is a closed loop:
CAD Design → CAM Planning → Post-Processing → Sending G-code → Homing → Setting Zero → Clamping → Dry Run → Physical Cutting → Quality Inspection.

Each stage is the foundation for the next. Following this standardized workflow is the most reliable way for beginners to transition to high-precision CNC manufacturing.