Why does my 3D finish toolpath take so long and how do I speed it up?

Overview

Long finish toolpath times are almost always a stepover problem. The finish toolpath always cuts the entire model in a single pass, so the main variables controlling time are the stepover percentage, the tool size, and the feed rate. This applies to both VCarve Pro and Aspire.

The Math

A 0.125" ball nose at 8% stepover makes passes every 0.010". For a 12" x 12" piece:

• Total passes: 12 / 0.010 = 1,200 passes
• At 100 IPM: 12" x 1,200 = 14,400 inches of travel = 144 minutes

Double the stepover to 16% and you cut the time in half to 72 minutes, with only a slightly visible quality reduction.

How to Speed Up Without Sacrificing Quality

1. Increase stepover (biggest impact)

These are starting points to test on scrap. The official documentation calls 8 to 12% of the tool diameter typical for ball nose finishing.

• 8% = very fine, longest time (use for tight detail or customer-facing show pieces)
• 12% = good balance for most work
• 15 to 18% = faster, slightly visible ridges, good for paint-grade or primed work
• 25% or more = rough finish, visible scallops, only for test cuts

2. Use a larger finish tool where detail allows

A 0.25" ball nose at 10% stepover finishes large areas much faster than a 0.125" at 10%. Use the larger tool for background areas and the smaller tool for tight detail.

3. Use more than one tool (rest machining)

In the finish toolpath, add a medium tool (e.g., 0.25") as the first tool in the tool list, followed by the small ball nose. When several tools are in the list, rest machining is used automatically: the larger tool clears large areas fast, then the small ball nose only cuts the areas the larger tool couldn't reach.

4. Increase feed rate

If your machine is capable, increase the finish feed rate. Many users run 3D finish at 100 to 150 IPM on hardwood without quality loss.

5. Restrict the machining boundary

Use a vector boundary to restrict finishing to only the detailed areas. Large flat background areas don't need a 3D finish pass. The roughing pass is sufficient.

Pro Tips

• Use the toolpath preview in the 3D view to judge quality before committing to a long cut. Zoom in on the preview, and use a higher simulation quality when checking fine detail
• Run the finish pass at a 45° raster angle to minimize fuzz on wood grain
• For MDF and HDU foam, you can run 15 to 18% stepover and still get a smooth surface. These materials sand much faster than hardwood