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

3D Roughing Toolpath for Rotary/Spindle Work

Applies to: Both (VCarve Pro and Aspire)

The 3D Roughing Toolpath removes bulk material from the blank before finishing. For rotary spindle work there are specific considerations that don't apply to flat machining.

When You Need 3D Roughing

The official documentation says roughing is used when carving 3D parts to clear away excess material when the part is too deep for the finishing tool to cut in a single pass. For shallow surface detailing only, you may be able to skip roughing entirely.

Strategy Selection

Z Level Roughing: uses a series of 2D Pocket toolpaths that take the 3D model into account and hog out the material around it within the boundary, layer by layer. The official documentation says that for deeper parts, Z Level roughing is typically more efficient.

3D Raster: passes over the whole model surface. It leaves a more even amount of material for the finish cut to remove, but depending on the depth and style of the part it may take significantly longer. In shallower parts where roughing takes only one or two passes, it may be the better choice.

Machining Allowance

Set a machining allowance, a virtual thickness added to the 3D model when the roughing toolpath is calculated. 0.5 to 1 mm (0.02 to 0.04") is a common starting point to test. The skin left on the model serves two purposes, according to the official documentation:

1. Roughing is done with a relatively large tool and aggressive cuts, which is more prone to chipping, and the skin helps protect the finished surface
2. Most tools cut well when constantly removing material, so the allowance ensures the finishing toolpath always has some material to remove

Boundary Settings

The Machining Limit Boundary options are:

• Model Boundary: the combined boundaries of all components in the job (the area of the composite model that has components on it)
• Material Boundary: the boundary of the entire material block
• Selected Vector(s): selected vectors are used as the boundary
• Selected Level: the combined boundaries of all components on a named level

For spindle work with varying diameters, consider separate roughing toolpaths for regions of significantly different diameter. Wrapping distorts toolpaths more the closer they get to the rotation axis, so one toolpath for the whole model can give over-compressed passes in the narrower sections.

Ramping

Enable ramping instead of vertical plunging. Ramping reduces heat buildup and load on the spindle and Z axis, and reduces cutter wear.

Raster Direction

When using the 3D Raster strategy, choose Along X or Along Y based on which gives cleaner material removal for your blank orientation. You can reverse the stepover direction if needed.

Common Mistakes

• No machining allowance, so the finishing tool has nothing consistent to cut
• One toolpath for wildly different diameters (use separate toolpaths per region)
• Plunging vertically into rotary stock (ramp in instead)