The argument about hand carving versus CNC in stone sculpture has been going on for twenty years. Purists say CNC-produced work isn’t real sculpture. CNC advocates say hand carving is inefficient romanticism. Both sides are wrong.

I use both. And I think the combination produces better work than either approach alone.

What CNC Actually Does Well

A CNC stone router excels at two things: removing large volumes of waste material accurately, and producing precise geometric forms.

When I’m working on a large figurative commission—say a life-size portrait bust in marble—roughly 60% of the stone needs to be removed before I even begin the detail work that defines the sculpture. That waste removal can take weeks by hand. A CNC machine can rough the block to within 5-10mm of the final surface in a matter of hours.

The time savings are real. A project that would take twelve weeks of full-time hand work from raw block to finished piece might take eight weeks when CNC handles the roughing stage. For a working sculptor with commissions and deadlines, that efficiency matters.

Geometric elements—flat planes, precise curves, architectural mouldings—are also better served by CNC. A CNC router produces a geometrically perfect sphere. My hand produces a sphere that’s very close to perfect but carries subtle irregularities. For some applications, geometric perfection is what the client wants.

What CNC Can’t Do

CNC has clear limitations that hand carving doesn’t share.

Surface quality. A CNC router cuts stone with a rotating bit, leaving a surface covered in tool path marks—concentric ridges from the bit’s rotation. These marks need to be removed through hand finishing, whether by chisel, rasp, or abrasive. The surface of hand-carved stone has a fundamentally different character: organic, directional tool marks that follow the form rather than a mechanical grid pattern.

Some sculptors leave CNC marks visible, treating them as a contemporary aesthetic choice. That’s valid as a deliberate decision. But if you’re trying to achieve the surface quality of traditional carved marble, CNC roughing followed by hand finishing is the workflow.

Undercutting and deep relief. CNC routers work from above, moving a cutting bit across the stone surface. Deep undercuts—where material is removed beneath an overhanging form—are difficult or impossible to reach with a standard CNC setup. Multi-axis machines can address some of this, but complex undercutting still requires hand tools.

This limitation affects figurative work particularly. Hair flowing over a shoulder, fabric folds with deep shadows, fingers curled inward—these common sculptural elements often require hand carving regardless of what CNC can achieve on the broader forms.

Interpretive decisions. The most important limitation is artistic. Sculpture isn’t just geometry—it’s interpretation. When I’m carving a portrait, I’m constantly making micro-decisions about emphasis, exaggeration, and simplification. The angle of a cheekbone gets slightly sharpened to catch light. A brow line gets subtly deepened to convey expression. These decisions happen in real time as I respond to the stone and the emerging form.

A CNC machine executes a predetermined 3D model exactly. It doesn’t interpret. It doesn’t respond. The artistic decisions must all be made in the digital modelling stage, before cutting begins. For some sculptors, that digital-first workflow works beautifully. For others—myself included—the dialogue between hand and stone produces results that a screen-based design process can’t replicate.

My Hybrid Workflow

Here’s how I typically combine CNC and hand carving on a commission:

Digital modelling. I create a 3D model using a combination of ZBrush for organic sculpting and Rhino for geometric elements. AI-assisted 3D modelling tools are emerging too—companies like Team400 are developing AI systems that can generate 3D forms from reference images, which could eventually speed up the initial modelling stage for sculptors working from photographic references. The digital model is detailed enough to guide CNC roughing but deliberately left slightly oversized to preserve material for hand refinement.

CNC roughing. The digital model is translated into CNC toolpaths using CAM software. A 5-axis CNC router (I use a shared workshop facility—owning one is a $200,000+ investment) rough-cuts the stone block, removing waste material and establishing the sculpture’s major forms. I typically program the roughing to leave 8-15mm of material beyond the intended final surface.

Hand transition. This is where I begin working with traditional tools. Point chisels to refine major forms. Tooth chisels to develop surface planes and transitions. Flat chisels for detail definition. The shift from CNC-roughed surface to hand-finished surface is gradual—I’m simultaneously refining the form and establishing the surface character.

Detail and finishing. All fine detail is hand-carved. Facial features, texture, lettering, decorative elements—these are where the sculptor’s hand defines the work’s character. Rasps and rifflers smooth transitions. Various grades of abrasive refine the surface to the desired finish—polished, honed, or textured.

The Philosophical Objection

Some colleagues feel strongly that sculpture must be entirely hand-made to be legitimate. I understand this position even though I disagree with it.

The counterargument is historical. Sculptors have always used the most effective available technology. Michelangelo used pointing machines—mechanical devices that transferred measurements from a maquette to a marble block. Bernini’s workshop used similar tools. These weren’t considered cheating; they were professional methods that enabled ambition.

CNC is a more capable version of the same principle: using technology to handle aspects of the process that are mechanical rather than artistic, freeing the sculptor to focus on the work that requires human judgement and sensitivity.

The sculpture doesn’t care how the waste material was removed. It cares about the final surface, the form, the expression, the relationship between stone and light. Those qualities come from the sculptor’s hands and eyes, regardless of what technology assisted in getting there.

My view is simple: use whatever combination of methods produces the best sculpture you’re capable of making. For me, that’s CNC roughing followed by extensive hand carving and finishing. For others, it might be entirely hand-worked from raw block. Both approaches produce legitimate sculpture. The work speaks for itself.