How does toolpath simulation/preview work in VCarve Pro & Aspire: quality settings, animation mode, and material shading?

Overview

The toolpath preview lets you see what a calculated toolpath will produce when cut into the material. The 3D preview mode also lets you view the job in different material types and paint the machined regions with a fill color. It works the same way in VCarve Pro and Aspire. It is a very useful guide, but it is a simulation: a problem you can see in the preview will usually show up on the part, while a problem that appears only on the machine is more likely a physical machine issue (runout, flex, missed steps) than a toolpath issue.

Accessing the Preview

The Preview Toolpaths form is part of the Toolpaths tab. You can also reach it from the Toolpaths menu. While the preview is active, the 3D view shows the simulated material block instead of the composite model.

Preview Simulation Quality

This is the most important preview setting. It is in the Toolpaths menu, under Preview Simulation Quality. It sets the resolution (number of points) of the simulation model, so a higher quality shows more detail but is slower.

The slowdown figures are guidelines. They depend on your PC and on the size of the tool relative to the job (the larger the tool, the slower the performance).

Practical workflow: work at Standard while you iterate, then switch to a higher setting for the final review before cutting.

Preview quality is not job resolution. The simulation quality setting only affects what you see in the preview. It does NOT change the toolpath data or the cut quality.

Preview Quality vs. Job Size

From Learn Your CNC: preview quality depends on the job size AND the quality setting together. A detailed design in a large job (48" x 96") can look blurry at a low quality setting because each point of the simulation represents a larger area.

Two ways to improve preview quality:

1. Increase the Preview Simulation Quality setting (slower)
2. Reduce the job size to match the actual part (faster, because the points represent a smaller area)

For customer proof images: temporarily shrink the job to just around the design, save the preview image, then restore the full job size.

Preview Buttons and Controls

Material Shading Options

The color palette icon opens the Material Appearance dialog, which controls how the simulation looks:

• Use Solid Color: a plain single color for the material
• Use Material: pre-defined material effects, including many wood grains, metal effects, stone and plastic
• Custom materials: add a category or texture from the list itself (<Create new category...> and <Add new texture...>), or copy a JPG, BMP or TIF image (about 1000 x 1000 pixels) into the Textures folder inside the Application Data Folder. Open it with File > Open Application Data Folder
• Machined Area Color: Material Color (machined areas use the material), Surface Color (paints the uncut surface, to simulate painted wood with the wood texture showing in the cuts), Global Fill Color (paints all machined regions), or Toolpath Color (a different fill color per toolpath, useful for multi-color sign work)
• Lithophane mode: shades the preview as a semi-transparent material lit from behind. The thinnest areas appear brightest, and the brightness drops to its lowest at full material thickness. A slider adjusts the effect to match your lighting. Use it to check a lithophane before cutting

What the Preview Can and Cannot Show

Preview is a good guide for:

• Toolpath coverage and misses
• Depth of cut
• Surface finish patterns (stepover visible)
• Over/undercutting
• Tab placement on profile cuts
• Toolpath order issues

Preview is NOT fully accurate for:

• Rotary/wrapped jobs: drilled holes can appear as distorted ovals because of the stretching used to display the wrapped simulation. Trust the flat view for dimensions
• Physical machine errors (runout, flex, missed steps)
• Tool wear effects
• Material grain behavior