Prepared from parser behavior, machining-file examples and visual checks performed in CNC Viewer. Always confirm the result against the CAM setup and machine documentation before production.
Preview performance
CNC simulation density, accuracy and performance
Simulation density is a sampling decision, not a machining parameter. It controls how finely the stock surface is represented and therefore affects edge smoothness, memory use and calculation time.
What density changes
A height-based solid preview divides the work area into cells and records the remaining surface at each sample. More cells capture narrow grooves and curved boundaries more clearly. The programmed tool center, cutter diameter and Z depth must remain unchanged between density settings.
If increasing density changes a 9 mm channel into an 18 mm channel, the problem is radius handling rather than resolution. Diameter should be halved once to obtain the cutter radius and applied around the centerline once.
Why a larger cutter can take longer
At each path sample, a raster simulation updates every grid cell touched by the cutter footprint. A larger radius covers more cells, so the work per sample rises with the cutter area. Long relief paths multiply that cost even when the final picture looks simple.
Efficient implementations stamp cached circular footprints, group segments by tool, skip non-cutting moves and process the file in chunks so the page can update a loading percentage. These optimizations reduce repeated work without changing the physical sweep.
Use the lowest setting that answers the question
Medium is a practical default for stock size, depth ranges and major pockets. High is useful for smaller holes, curved contours and a closer comparison between toolpath and removed volume. Ultra is best reserved for final inspection of a limited area or a file whose smallest feature genuinely requires it.
A technical drawing and operation statistics often answer coordinate questions faster than a denser mesh. Density is most valuable when the uncertainty is visual edge quality, not when the uncertainty is the source operation data.
- Medium for first inspection
- High for small curved features
- Ultra only after dimensions are verified
Recognize source complexity before rendering
Large files may contain millions of nearly collinear points, duplicate drilling records or rapid movements that do not cut. Simplifying a path within a small geometric tolerance can reduce cost, but Z changes, tool changes, arcs and cycle boundaries must be preserved.
A safe complexity limit should explain whether the file exceeded line, point or estimated raster-work limits. That is more useful than a generic parse failure and allows the operator to choose a lower density, hide source text for large files or simplify the CAM export.