Getting Started with the CNC Router

Cutting Topographical Maps on the CNC Router

This guide serves as a central reference point for fabricating detailed topographical maps using a CNC router. While this article originated from my own personal workspace notes, documenting the nuances and hurdles of computer-aided manufacturing (CAM) workflows provides a foundational guide for anyone attempting to carve intricate landscape geometries.

As this project continues to evolve and further technical challenges arise, I plan to expand upon the strategies outlined below.

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Preparing the Model: SketchUp to Rhino

The physical creation of a topographical piece begins digitally with source terrain data and a reliable 3D modeling pipeline. The primary workflow relies on SketchUp, Google Earth data, and Rhino for scaling and machine path generation.

1. Source Terrain Acquisition: Using the Google Earth plugin inside of SketchUp, use the Add Location feature under the Geo-location options to choose the desired terrain boundaries.
2. Terrain Extraction: Ensure that the software is displaying actual terrain contours by activating the Show Terrain toggle.
3. Model Exportation: Export the resulting geometry directly from SketchUp as a .3ds mesh file.
4. Re-scaling & Sizing: Import the .3ds file into Rhino, choosing the Component / 3D Model import type. From here, establish your workpiece bounds, taking note to scale dimensions precisely against your target physical stock material.

Generating Machine Operations

Once the digital model matches real-world dimensions, toolpaths are constructed to safely and efficiently transform raw timber into topographic contours.

• Establishing Toolpaths: Prepare the raw model inside CAM software (such as Aspire or RhinoCAM) by configuring the material setup and tool database.
• Roughing Operations: Execute a 3D Rough Toolpath first. This operation utilizes a larger end-mill or roughing tool to remove bulk stock quickly in stepped layers, leaving a stepped approximation of the terrain.
• Finishing Passes: Conclude the physical machining with a 3D Finishing Toolpath. Using a smaller ball-nose bit and tight stepover tolerances, the finishing run tracks the exact curvature of the imported terrain to produce smooth, sweeping topography.