How do I set up a 3D Finishing Toolpath for a rotary spindle in VCarve Pro & Aspire?

3D Finishing Toolpath for Rotary/Spindle Work

The 3D Finishing Toolpath refines the surface left by roughing, producing the final smooth surface on your spindle or rotary project. It works the same way in VCarve Pro and Aspire.

When to Use

After 3D Roughing has removed bulk material, the 3D Finishing Toolpath takes light passes over the entire model surface. For purely 2D rotary work (flutes, pockets, profile cuts only) you may not need a 3D finishing pass at all.

Tool Selection

Choose a ball nose bit appropriate to your detail level:

• Large ball nose (1/4" or bigger) for smooth simple curves and large spindles
• Small ball nose (1/8" or smaller) for fine detail, tight flute profiles, or decorative clipart
• Tapered ball nose gives good detail with more tool strength than a straight small-diameter bit

Stepover for Rotary Finishing

The official 3D Finishing documentation says a ball nose with a reasonably small stepover is typical, 8 to 12% of the tool diameter. A larger stepover leaves visible scallop marks. The finishing pass takes longer but delivers the final look.

Rotation Axis Consideration

Remember which axis is physically rotating. If your rotary axis moves more slowly than your linear axes, a raster direction that limits rotation axis movement may finish faster. Test the direction on scrap, because this depends on your machine.

Machining Boundary

Limit the finishing toolpath to the model boundary to avoid air cutting outside the 3D model area. For clipart or raised decorative elements on a flat rotary surface, you may want to restrict the boundary to just the raised area.

Handling Varying Diameters

For spindles with significantly different diameters at different sections:

• Generate separate 3D finishing toolpaths per region with distinctly different diameters
• Set each toolpath's boundary to its own diameter region
• Reason: wrapping distorts toolpaths. Wrapped toolpaths match the flat toolpaths only at the surface of the blank, and the effect grows closer to the rotation axis. A single finishing pass over the whole model can therefore produce over-compressed passes in narrow sections.

Projecting onto the 3D Model

If 2D toolpaths (pockets, profiles, flutes) were calculated before 3D clipart was added, recalculate them with Project toolpath onto 3D model enabled. Otherwise the 2D toolpaths cut at flat depth and ignore the 3D model surface.

Simulation

Turn on Auto Wrapping on the View Toolbar to preview the wrapped result. The animated preview runs in flat mode, then switches to the wrapped view automatically when complete. The wrapped simulation is approximate and is not 100% accurate for round features.

Common Mistakes

• One finishing toolpath over a large diameter range (use per-region toolpaths)
• Stepover too large, leaving visible scallop ridges on the finished surface
• Forgetting to project 2D toolpaths after adding 3D model elements
• Wrong post-processor selected when saving (always use the wrapped variant)